Classic Hymers for new owners and beginners. Updated 2020 version.

Classic Hymers for Newbies! (Updated for 2020)

A lot of owners are old hands and take the basics for granted. But we all have to start somewhere, and if you have just bought your first Classic and have no idea how it works, then this extremely basic guide will get you on your way.

This guide should be useful to most pre 95 Hymer owners. But bear in mind that there may be differences, especially with fridges.

New in 2020 - more photos, updated info and a new section at the end on common faults, accident damage and suppliers.

Electrics

The first thing to remember is that a motorhome is a caravan body on a commercial van chassis, even the ones that look as though they don't have a recognisable cab. Think of the van as a "load" on an empty van chassis. Merc or Fiat made the engine, controls and chassis, and Hymer then built the van onto it. This means that all the electrics and systems on the base chassis are different and separate from the van electrics and systems. So you have Hymer electrics, and you have Fiat or Merc electrics, and the two systems are completely separate. This is why the van has 2 fuse boxes - one for the Hymer side and one for the Fiat or Merc side.

You have two batteries. One for the Merc or Fiat chassis, and one for the Hymer and they are completely separate. The chassis battery does not power the living part of the van (also known as "habitation") and the habitation battery does not power the chassis - i.e. it won't start it.

These two batteries are fundamental to your understanding, and from now on will be referred to as LB for leisure/van battery, and VB for vehicle/chassis battery.

Both batteries are charged from the engine when you are driving. So when you arrive on site you should have 2 fully charged batteries. The LB will then power your living area, and the VB will do absolutely nothing. This means that you can run out of power from the LB, but the van will always start, and as soon as you do, the LB will start to be charged up again from the engine. VB power is never used for living - it's only for starting the van.

A common mistake is to leave the headlights or sidelights on all night, and flatten the VB. Nothing can prevent this except getting into the habit! At least you can make a cup of tea while you wait for breakdown to come and start you up. We've all done it!

All the exterior lights - sidelights brake lights etc, are fused from the chassis fuse box. All the habitation interior lights are fused from the Hymer fuse box.

On Mercedes there is usually a battery box that contains both batteries - LB and VB, and the habitation fuse panel is adjacent to the drivers left knee (LHD vans). 

On Fiats and derivatives the VB is usually under the bonnet, and the LB is under one of the front seats. The habitation fuse panel is usually by the drivers left knee (LHD vans) or the passengers right knee (RHD vans).

The fuse box in classics uses the old style Bosch barrel fuses. These are still available online and from Halfords. Behind the fuse panel is a box, which pulls out if you remove 4 screws. In this box are the relays and the shunt. Just so you know.

The vehicle fuses are usually in the passenger footwell somewhere.

There is a big red switch handle close by the habitation fuse box. You can't miss it. This is the 12v emergency cut off switch. Normal "on" position is down. To isolate, turn it either way so it pops out. This is only for emergency, normally it should be left on. You can switch off for winter storage if you like. If you smell burning, like plastic burning, then you operate the big red switch, and then outside unplug the van if on hookup. Fires are rare, but they do happen. Make sure you have a big, up to date, fire extinguisher, a proper smoke alarm, and for good measure, a carbon monoxide alarm. Especially if you have children.

Control Panel

Most classics have a panel with 2 meters. One marked "Spannung" and the other "Strom". This is German for Voltage and Power. Next to the left meter, voltage, is a switch marked Battery 1 and Battery 2. It's a rocker switch. When you press either way, then the meter should light up, and the needle will indicate the voltage of the battery. Battery 1 is the VB, and should never change when you are parked up, and battery 2 is the LB, and this will very gradually reduce from over 12v to below 11v as you use the power from your LB. You will see that the dial is calibrated not only in volts, but in green and red zones! You should avois running the battery into the red zone. In fact, by modern standards, the red zone starts a bit too low, you shouldn't really run a battery below 11.5 or 12v. But the old Hymer meters are not as accurate as modern digital ones, so there is a bit of leeway.

You can get some indication as to the health of your battery by looking at the voltage meter, but only when the battery is "resting" ie not being charged or discharged. So if you have solar, wait until night, and not on EHU. A fully charged battery will "rest" at 12.8v and will fall to around just under 12v as it discharges. So in the evening, when you are on battery power only, you can get an indication of how well your battery supplies your needs. If it regularly is at under 12v by bed time, perhaps after you have been using a TV or something else, then maybe it's time to look at your system - regularly discharging a 12v battery to 11v and below will shorten its life - but that depends on the quality of the battery.

The right hand meter - Strom - has the needle always in the middle - known as "centre zero". Green zone to the right of the needle, and Red zone to the left. If the needle is in the red, then you are using power. If the needle is in the green, then the LB is receiving power by being charged. With the engine running, or on hookup (more on hookup later) then you should see the needle in the green. There is no control of this meter - it is for info only. But by looking at it when you switch things on and off, and comparing it with the voltage of Batt 2 (LB) you should over time get familiar with the power system in your van, and it is good for troubleshooting. It is calibrated in amps, but again, it is not very accurate by modern standards. The main thing is that it should deflect either way to indicate charge or discharge, but bear in mind that this will change according to the state of charge of the battery - if the battery is fully charged then don't expect to see the needle deflect much into the green, It will only do so if the battery needs and is receiving a big charge.

A very useful and cheap accessory to fit in a classic van, is a digital volt meter - points of a volt are important at 12v, and having a digital meter to 2 decimal places is much better than an old analogue needle meter. These days every owner needs lots of USB sockets. These are easy to fit, and some of the better ones have a digital voltage display as well.

Also note that if you have solar panels fitted, the charge from these may not be indicated by the Strom meter. Solar panels were not a factory option and were often fitted direct to the battery, and not via the meter. 

While you are hooked up to EHU, the voltage meter will be up above 13v all the time and the Strom meter will generally stay in the green all the time.

On the very left is a switch marked Frischwasser/Abwasser - this means Freshwater/Greywater and when pressed will indicate the level of either the fresh water tank, or the grey water tank. The lower part of the meter is calibrated "leer" 25% 50% and 75% and "voll". leer = empty, voll = full. It is not a continuous display. The level is not driven by a float as in a petrol tank on a car. There are 4 sensors in the tank, so the needle will jump between the 5 positions. It is only a rough guide. In old vans this system often gets clogged with dirt and stops working after many years.

In the middle of the panel is the dreaded "switch with no name". This is an extra switch for options and/or owner fitted modifications. Yours may or may not do something. On many vans it has no function. Possible uses have been known to include - water pump isolation switch, external light switch. 

Next to this is often a switch named "Lufter". That means fan, and operates the fan in the space above the cooker, to extract cooking smoke. There should be a lever under the panel which opens and shuts an external vent. All vans are different, so just check yours out and work it out.

On the right there is a light switch called "Licht" which operates the kitchen light. On many vans there is also a switch by the entrance door for this light - similar to the two way switches that operate the landing light in a house.

On most classics, the whole control panel is secured by just 3 screws along the front lip and if you undo these the panel will drop down on hinges, exposing the gubbins inside. many panels have a clock and/or a radio fitted - this is how you get at it. It also gets a bit dirty in there because of cooking, so you should have a gentle clean around every few years.

All the other lights in the van are usually operated by switches built into or adjacent to the lights themselves. Most Hymer original lighting consisted of 12v halogen spots and 12v strip fluorescent tubes. In the bathroom many vans have a column light with 4 bulbs in it.

Ever since the introduction of LED lighting most owners have converted all their lights to LED thinking they will save power. While this is true in theory, in practice it isn't as much as you might think. If you still have original lighting, think twice before ripping out the original lighting, especially if you like the "retro" look and feel. Some LED lighting can be harsh and not comfortable and should be planned and designed carefully. I have written about this elsewhere on this blog (see index). If you do convert to LED, the golden rule is always make sure you buy "warm white" LEDs, not "cool white".

The 12v strip lights are now obsolete - you can still get the tubes, but not the shades and transformers. These can be nicely converted using 12v warm white led strips inside and look good while preserving the original design.

Electrical Hookup - also known as EHU.

There is a socket on the side of your van and you should have a cable that you can hookup to the mains on a campsite or at home (with a suitable adaptor).

On most vans there is an electric socket somewhere in the kitchen area, and also in the TV cabinet if fitted. All vans are different so look for your sockets. These will be euro style, so buy some adaptors. You can usually plug anything into these that you would at home, but not always. Many campsites limit the amount of power available through the hookup, so anything powerful that generates heat - kettles, toasters etc, may either not work, or trip out the supply. All camp sites are different, especially on the continent, but generally you should be able to run a kettle or a toaster in the UK. Most people use a gas kettle. TV's and laptops and most other stuff can be powered from these sockets, and the sockets are only live when hooked up. For the technically minded most UK campsites use 10amp trips, which is equivalent to about 2200w or 2.2kw. This is more than enough for hairdryers, microwaves, kettles, oil radiators, small fan heaters and coffee machines. European sites often (but not always) have lower trips - 6amp or even less.

While you are hooked up, your LB will be charged up by a battery charger. Usually this is a small blue box hidden away somewhere. Sometimes it emits a gentle hum. It should just work, and you should see the needle go into the green when hooked up. You should remember that when hooked up, all your lights and fans, in fact everything that works on 12v when you are not hooked up, are still powered from the LB. But the LB receives enough charge from the battery charger to compensate for this use, and stay charged. The only things on the van that actually use 240v are the fridge, and the charger, plus whatever you plug into the sockets. Everything else still works on 12v, even though you are hooked up.

By modern standards the blue box charger is old technology. Modern chargers are digital and make a better job of charging and maintaining your battery when on EHU. While there is no pressing reason to change - if it works don't fix it - if the situation does arise that your battery charger gives up the ghost and needs replacing, then replace it with a modern digital charger of 10 to 15 amps. Ask on the groups and forums for recommendations, or consult your dealer if you have one. (Note - this applies to pre 95 vans that have a separate charger. 95 is about the time they started to fit "Elektroblock" chargers made by Schaudt. If your van (most pre 95 classics don't) has an Elektroblock, then this doesn't apply to you. If in doubt, ask)

Mains 220V

Somewhere in the van is a small consumer unit - similar to the one at home but much smaller. It has trip switches that will cut off the mains in emergency or a fault. You should know where yours is as it is the first place to look if the power goes off. For the reasons stated in the last paragraph, the lights and fans will stay on if the hookup power goes off, but the fridge and the charger will stop working if it trips out. So learn how to recognise when you are on hookup, and when not. Many a fridge full of food has been ruined and a LB run flat, when you thought you were hooked up, but were not. The green light on the fridge, if fitted, is the easiest indication of this. Many owners get into the habit of pressing the Battery 2 button when they pass. When hooked up it should always be well over 13v. If it starts to drop when on hookup, then start looking for a reason.

A fully charged LB should do you for a weekend of wild camping with no hookup, assuming normal use.

Inverters

An inverter converts 12v battery power to 220v when you are not hooked up. They were not fitted as original equipment, so are beyond the scope of this article. However, if you do have one, then familiarise yourself with it and how it works - ask on a group or forum.

The same goes for 

Solar

Solar was not fitted by Hymer at the factory, but many vans had solar fitted by the dealer when the van was brand new. So you could have a solar system that is original and nearly 30 years old. Or it could have been fitted at any time since either by an owner or dealer. It may or may not work well - no way to know without testing it. However it is fair to say that modern solar systems are much more efficient that they were 30 years ago, and lots cheaper - so if you want solar, then make sure your system is up to scratch.

Water system. 

Somewhere in your van is a fresh water tank. You fill the tank with water - please don't put diesel in it! In the tank is a submerged pump. In each tap there is a hidden electrical switch called a microswitch. When you open a tap, the pump operates, water comes out. The pump has a fuse in the habitation fuse panel. It is not a pressured system like in a house, although there is a slight pressure. A common problem is that the switch in the tap fails, so the pump doesn't operate. You can prove this by opening the faulty tap, and then opening a different tap - water should come out of both taps. This is a useful work around if you have a faulty switch - until you can get it fixed.

Can you drink the tank water? Generally yes - I have for 20 years. But old vans can get a bit tainted so use your nose. There are all sorts of methods of cleaning the tank and pipes - it's just the same as a caravan or boat.

Waste Water - Grey Water

The waste water goes down the plug, into a tank - called the grey tank. On the tank outside is a valve. you empty the tank when you can down a grid. There is sometimes an extension hose hidden within the back bumper of the van. If you are lucky, the gauge on the control panel will display the level of fresh and grey water in your tank. If not, you have to guess, but it is normal just to empty your grey tank whenever you get the opportunity - usually when you fill with fresh. 

The grey tank can smell a bit in summer. Many owners mistake this smell for the toilet - it's not. What happens is that the grey tank never really gets full - it gets emptied regularly, so what happens after many years is that it gets a bit crusty in the upper half of the tank, and it gets worse in summer when it's hot and the odour backs up through the sink plug holes. You can minimise the problem by regularly rinsing a dash of bleach down each plug hole - you don't need a lot. Another favourite you will see online is cheap cola - I think it's rubbish, but you can try it. If it gets too bad, then a good trick is to fill the grey tank right up to the top with water bleach and disinfectant and then go for a nice long drive, and then empty it out at the other end. This should clean the upper reaches of the tank and make the problem better.

Hot Water

Most vans have a Truma boiler like this (but maybe not identical) hidden away somewhere in a cupboard or under the bed. Basically it is a big pan of water in a box, heated by gas and controlled by electricity. There is a control box with a switch and a dial. The switch switches it on and off, and the dial sets the temperature, from lukewarm to scalding hot. It's as simple as that. It needs water and gas and electricity -  you press the switch, and after a few seconds you should hear a clunk, and the green light comes on. If you get a red light, there's something wrong. The commonest reasons for a red light are either a flat battery or no gas. Another common fault is a blocked flue - quite often after winter storage animals or insects have nested in the flue outside. There should be a winter cover to prevent this, but it often gets lost and forgotten. The heater won't work if the winter cover is left on.

There is 10 litres in the tank, and it takes about 20 minutes. You can get a leisurely shower for one, or a quick shower for two. You will feel the shower water get cooler, but you can increase the hot flow on the shower tap and get one last minute or so to rinse. The hot water doesn't just disappear, you get a few minutes warning.

It is OK and not particularly wasteful of gas or electric to leave the water heater switched on, particularly if you are a busy family. Or you can switch it on as required - but its up to you. 

Heating

Most vans have a brown panel heater that looks like an old fashioned storage heater. It is made by Truma and on 5 series vans it is usually a Truma 3002. On 6 and 7 series vans it is often a Truma 5002, which is just a bigger version. It has a dial on top. Like most old fashioned gas heaters, you press and turn the dial, and release when the flame is established. If you look closely you will find a tiny inspection window and you should see the flame. You may hear a tic tic sound, which is the ignition system. 

Not only does this brown heater radiate, but it also (in most vans) heats up hot air and a fan blows the hot air through a system of ducts to outlets all round the can. Look for these outlets, around 4 inches round, and they should have plastic butterfly valves that enable you to adjust the flow of air. They are similar in concept to the air vents in a car.

The fan that blows this warm air has its own control, and if you want hot air distribution then you must switch it on, after lighting the heater. It's a little brown box like the others, and is usually marked "Truma Vent". The switch is 3 way, centre off. Up operates the fan manually, and the dial sets the fan speed. Down is an automatic setting that is supposed to adjust the fan speed according to a thermostat in the switch. On many old vans this function is either not working, or unpredictable and so most owners use the manual option. It is also useful in hot weather to run the fan at full speed with the heater off, as this will circulate air around the van. This fan can "sing" as it gets older. The bearings get worn. usually you can find a setting where it isn't too bad. It's the Hymer sound. 

The fan also gets very dirty with dust after 20 years or more - cleaning it can improve circulation dramatically. There is another article on this blog about this here about this.

https://hymers700.blogspot.com/2019/01/cleaning-truma-blown-air-heating-fan.html

Running the fan all night is fine - how else are you to keep warm in winter? It does use some battery power, but not much. A fully charged LB should run the heater fan non stop for at least 48 hours. You van has blown air central heating - don't be afraid to use it!

On some vans if the LB runs flat, the fans will stop, but the heater will still radiate.

Fridge

No other appliance causes more grief than the fridge! But you have to remember that in most Classics, the fridge, which was state of the art 20 years ago, is now over 20 or even 30 years old, and may or may not have been serviced regularly. There are quite a few different fridge designs used in Classic Hymers, so I can't be specific about your fridge, but I can describe the basics.

The fridge works on mains (when you are connected), gas, and some work on 12v but only when you are driving.

It is a common misconception that the fridge works on 12v from the LB. It doesn't. It only works on 12v fed from the engine alternator when the engine is running. This is because the fridge needs a lot of power on 12v, too much for the LB, so is only designed to work on 12v when driving. Most fridges have a red switch to select 12v operation. Some red switches illuminate, others don't. This switch has no function unless the engine is on, but needs to be on if you want 12v cooling when driving. When on 12v when driving the fridge does not stay as cool as on gas or hookup. It is just designed to keep cool while driving. Don't load up a warm fridge with new food at the start of a long drive and expect it to be cool when you get there on 12v. Pre-cool the fridge the day before on hookup or gas so you load food and beer into an already cold fridge. Use ice packs or even bagged ice, especially in summer, to pre cool the fridge if you can't have it on for 24 hours first.

Most fridges have a green switch, which may or may not illuminate. This switches the fridge on from 240v hookup. It will only work if you are hooked up.

Gas. It depends on your fridge model, but the basics are that you press and turn the gas dial and hold it in until the fridge ignites. Ignition can be automatic - with a flashing red switch, or manual, with a button you press. I can't be more specific as there are many different fridges. Some fridges have a window, some fridges you can hear the gas, on some fridges the red ignition switch stops flashing when the fridge is lit, and starts flashing again if the gas goes off for some reason. Hopefully you have a manual.

When on gas, but hooked up, the green switch should be off. You should not operate the fridge on both mains electricity and gas at the same time.

The gas part of an old fridge is the most likely to fail - it really needs a service every year, and should be part of your annual habitation check.

"Fridge doesn't work on gas"

This is the commonest problem and most asked question on all the groups and all the forums, not just for Hymers, but all caravans and motorhomes over 20 years old. Here is the basic information as to why this is.

The first golden rule is this - if your fridge doesn't work on gas, then get it plugged in to EHU as soon as possible. If it then works on 220v then there is nothing wrong with the actual refrigeration bit - it's just the gas bit. But if the fridge does not work on 200v or gas, then that could be serious and it may be time to get a new fridge. The simple rule is this - in order to work, the fridge only needs a source of heat - either from the gas burner, or from the 220v element. If it works on either one, then the problem can usually be fixed.

The reason it fails on gas more than on 220v is that there are more moving parts on the gas side, and the gas side needs regular cleaning and maintenance. the 220v element is very simple by comparison - it either works or it doesn't.

This is how the gas system works. At the back of the fridge there is a chimney - it is actually a heat exchanger but it looks like a chimney. Inside it is the 220v element. There is also a 12v element on most fridges - only used when driving. At the bottom of the chimney is a small tin box, and inside the tin box is a burner. It's a bit like a tiny gas stove, only the ring is the size of a 20p piece and the flame is about the size of a medium sized candle flame. But it should be blue, and make a very gentle roaring sound.

The commonest problem is that years and years or dirt and dust have got in there and have prevented the flame from either igniting, or making it too small. In most cases all it needs is a good clean. It is such a common problem that there are literally hundreds of articles, blogs and videos on how to do it, including on this blog, and the groups I manage on FB.

There are other reasons why a fridge might not work on gas, or might not be cooling well in summer (hint - bad ventilation, corroded connections), but these are also covered elsewhere. 

The main point is this - don't let a dealer sell you a new (£1000+) fridge until you have had it checked by yourself or an honest friend - they can be fixed. Also, do NOT take any notice of online rubbish about taking the fridge out and rotating it. Or vibrating it. While there is a grain of truth in these procedures, they have to be done in the correct way by an expert. Done badly or wrongly they can terminate a fridge that could otherwise have been saved. All this is covered elsewhere.

Finally - not all fridges can be saved - if it doesn't work on gas or 220v and has been checked by a pro, then there is not a lot to do. 3-way fridges work on a sealed chemical system that is closed. Eventually the chemicals separate and can't be remixed, and too much corrosion on the inside of the pipes blocks the circulation. But at least it lasted 20 or 30 years, which isn't bad.

Gas bottles and gas.

Somewhere in the van you will find a set of gas isolation switches with various symbols on them - e.g. a snowflake for the fridge gas supply. These have a purpose, but for the purposes of this basic guide, you should not touch these on a day to day basis. Leave them on. 

Convention is that you should turn off the gas at the bottle when driving. Many owners don't. You should always turn off the gas at the bottle for storage.

I can't tell you how to change a gas bottle, because it's a safety issue. Get somebody competent to show you. Once you know - you know.

With fridge on gas, normal cooking, and the odd blast of heating in summer, or heating on permanently in winter, then you can expect one 11 or 13kg gas bottle to last you a month in summer, or a week in winter. This is an extremely broad estimate. The fridge and the water heating and cooking use relatively little gas, but the central heating if on 24/7 in a cold winter will use a bottle in 4 to 7 days depending on how hot you want to be and how cold outside.

Hymers are all weather vans - people go skiing in them. You can be 25 inside and minus 10 outside - it's just a matter of gas. 

In normal use, most new owners are pleasantly surprised at how little gas their van uses. But it pays to understand and get a feel from it, as unlike the other systems, there is no meter that tells you how much gas you have left. You have to get a feel for it. Some owners shake the bottle to see how much is left, others feel down the side of the bottle with their hand because the actual level of the liquid gas is colder, but most folk have two bottles, and swap over when one empties, and then know to get a new bottle when they can.

Many vans have refillable systems fitted, either refillable bottles or underslung tanks. Ask online about these.

The 50mb issue

This is a bit technical, but it is very important. Pre 95 classic Hymers left the factory with 50mb gas pressure systems. This was unique to pre 95 Germany. The rest of Europe used 37mb gas pressure. A pre 95 Hymer has gas appliances - the cooker fridge and heaters set up for 50mb gas pressure, and the bottles have 50mb regulators. There should be a big square sticker in the gas locker that says 50mb.

The problem is that because the UK never used 50mb, when a van was imported into the UK, many dealers simply didn't know this, so innocently replaced things with 37mb components - especially regulators, which have to be changed every few years by law.

So the basic rule is this - all owners of pre 95 classic Hymers should know about this and have their vans checked by a pro - a pro who is familiar with the problem. There is lots and lots of info and discussion online and on the groups, so new owners should ask.

Common situations are - new 37mb regs being fitted when all the appliances are 50mb. New 37mb fridges or heaters being fitted to a 50mb van. If you are a new owner - seek advice.

Cooker

Press and turn and ignite manually. Buy a gas wand.

Ovens

Ovens are a uniquely British thing - the Germans simply never fitted them! If your classic has an oven, it has likely been fitted afterwards.

Sewage - Black Water

Most Classics have a Thetford C3 cassette toilet system. It has a big knob that you turn to open the flap, and press to flush.

You open the toilet flap, do your business, press the button and if you are lucky you will get a bit of flush water - clean the bowl with the brush and push the doings down into the tank. Close the flap.

You will see when it starts to get full.

Outside the van there is a small door. Open the door, press the yellow safety catch that holds the cassette in place. Pull out the cassette, toddle off to the nearest disposal point, take off the yellow cap, press the air release button, and pour away. Pour in some blue fluid (see the side of the bottle) and leave a few litres of fresh water in the cassette. There is always a hose at the disposal point. On camp sites the water hoses for drinking, and flushing the sewage are separate by law, even though it's the same water. NEVER mix them up and use them for the wrong purpose.

Those are the basics of the dreaded cassette!

The commonest fault is either no flush, or a dribble of flush that pools in the bottom of the bowl. There is a valve inside (under the toilet roll holder) called a solenoid valve, and this usually dies of old age after 20+ years and needs replacing. The info is online.

Windows

The windows are delicate! Approach them with care, learn their little ways and never ever force them. Correct operation should be smooth and need no strength. Windows in Classics often get worn with age. Everything can be fixed, but they are fiddly to work on. 

Each window catch has a button which should always be pressed when operated. Don't force the catches. The window is held open by stays at the side. Some stays are friction operated, some stays have click latches. Gently learn how yours operate.

Most van windows have built in blinds. The blackout blind pulls up from the bottom. You squeeze the two buttons between finger and thumb, hold and gently pull up. If you release the buttons then let the blind down gently, it should locate in stops. If you look closely you will see that the buttons on the handle operate little pins on each side that locate in stops in the tracks at the side - hidden from view. Learn how they operate - they get worn on old vans.

Sometimes worn blinds will shut suddenly giving you a shock! This is because the pins get worn with age. Every window and blind in the van has its own character.

The flyscreens, fitted on most vans, pull down from the top. These don't have latches or buttons. You pull them down to meet the lower blind, and they should click together at the handle. The two blinds will then move up and down in unison. You can have a window open, the blind half up, and get fresh air but no insects. You can also have the flyscreen fully down and latched to the closed blind at the bottom for max ventilation and full protection from insects.

Do not get into the habit, at night, of ramming the lower blind up into the the closed flyscreen at the top in the hope that it will all click together. This will work, but will shorten the life of the blind. Pull up the lower blind almost closed, then pull down the flyscreen so it clicks and locks smoothly, and then raise them both to the fully closed position.

In summer or winter, with the blind fully closed, but the window slightly open, you will get some ventilation through the slots you can see in the frame of the window. 

Treat your blinds carefully! I have blogged about blind maintenance elsewhere.

Habitation DoorTreat the main door with respect - it is expensive if it goes wrong. The hinges have been known to break, and are hard to obtain. Don't let the door blow in the wind - secure it well. many a holiday has been ruined by a broken door. Keep an eye on it's fit and alignment and adjust as necessary.

Odds and Sods

Cab radio. Many radios in the cab are powered from the VB not the LB. If yours is so, then playing very loud music for a very long time may unexpectedly run down your VB. If this is an issue for you - get it sorted, it's an easy job to reconnect the cab radio to the LB instead of the VB. A few hours of gentle background music will not run down your VB, only hours and hours at full volume will. If in doubt keep an eye on battery 1 meter. If it drops below 12v because you have been playing the radio, then switch off, start the engine, and if successful, let it tick over for 15 mins. Then go get your cab radio rewired.

The step. Some vans have manual steps, others are electric. Some vans have a warning light that the step is down. Nothing is more embarrassing for a newbie than driving off with the step down and maybe causing damage. So get in the habit of a check list. Fridge on 12v, step up, heating off, roof light down, windows closed, cupboards closed and latched. The check list for every van will be slightly different - it's the habit that counts.

That's it!

This is a very basic guide, not an instruction manual. Most but not all pre 95 Hymers are roughly as described. 

Many vans have solar panels, TV systems, music systems, and all manner of accessories, but none of this is relevant to this very basic guide.

Common problems

Here is a list of the commonest problems that occur with classic Hymers, and all of these problems are covered in other blogs or in the groups online - I list them here so that if they happen to you, you will be at least re-assured a bit.

Mercedes

Loss of power on hills or even stuttering and then stopping. Cause - fuel starvation - the filters haven't been changed. Easy to fix.

Loss of ability to change gears. Cause - the selector arms on the side of the gearbox have come loose. NOT a new gearbox, so don't be conned. Easy fix.

Graunchy noises turning corners or going over bumps. Cause - worn suspension bushes.

Glowplug light comes on and bad cold starting. Cause - one of more glowplugs are faulty. easy fix - replace as a set of 5.

Temperature gauge climbs towards red zone on long hills. Cause - faulty viscous fan - ie fan not cutting in when it should. Also caused by an old radiator blocked with years of dirt. 

Engine rattles on tickover. Most old mercs have a distinctive tic tic tic which is the tappets, but if its a noisy rattle then it's nearly always the fanbelt tensioning mechanism. This needs replacing every 10 or 20 years. Lots of info online. Make a recording and post it online.

Fiat (and Fiat family). 

I am not a Fiat expert, but the commonest problem with older Fiats is the loss of 5th gear. This is covered online. Again, do not be conned into a new gearbox. It can be fixed easily, but you need to find a good garage that is familiar with the problem.

Habitation - the living area.

Dashboard appears to be moving on its own accord, on bumps and corners. Cause - The wooden dashboard has come loose after many years. It needs doing on most vans at some stage. It's a well documented fix - all you need is basic tools, drill and jigsaw, and a sheet of marine ply from the local merchants. At the same time you can re-soundproof the front of the van.

Leaking windows

Every time it rains heavily - really heavily in the wind - go round every window inside with a torch looking for water. The windows are sealed with sealer but this breaks down after many years. All windows on all vans need re-sealing at some point after 20+ years. It's a very easy job, but to do it properly you have to take the whole window out. Do not put new sealer on top of old, and do not use silicone. Loads of helpful info online. If you find water inside any part of the van, you MUST act. Damp and rot can ruin your pride and joy if left untreated.

Soft spongy floor

Most classics have floors not made of solid wood but of a sandwich type material with foam insulation. If you feel spongy bits, usually in the kitchen area, then don't panic. This can be fixed by injecting a special expanding foam. Ask online.

Leaking rooflights

Quite common, can be fixed, but act quickly otherwise your roof will rot.

Cracked shower tray and sinks.

Can be fixed nicely in situ by a company called Speedcoat. Shower trays are a big job to take out so try and fix in place if you can. If you just want a watertight fix and don't mind to see the repair, then you can fix with a special glue called Repaplas - ask online.

Sinks, cracked plug holes. We have fixes and suppliers for most problems. Ask online.

Water taps and showers - ask online.

Accident Damage. 

If you have an accident in a classic Hymer, most likely your insurance loss adjuster will try and write it off - most major repairs are likely to cost more than the insurance value of the van. Because the vans are old most dealers, including official Hymer dealers, won't want to know. The only way to hopefully prevent your precious classic being written off is to get an expert on the job. And there are only two in the country and one of those has just retired (Hambiltons in Preston). The other one is Peter Curry at North Cotswold Motorhome Services. Peter has saved many vans from write off, and knows old Hymers inside out. There may be others - if you know of one, let me know. Don't be pushed around by your insurance company. If you love your classic van, then agree an "agreed value" with your insurers. This will prevent any future shocks. I have known folk pay £15k for a nice classic but only been offered £9k as a write off.

Spare parts

Brownhills and Coastal Motorhomes are your main suppliers. But ask online for advice. Hymers are German vans and still very popular over there, but the German scene is hard to navigate because of the language problem. But we do have contacts if needed.

Your number one resource for Classic Hymer Technical info is the Facebook group I run called "Classic Hymers Technical" 

Funkronster's guide to motorhoming New Zealand on the cheap

New Zealand is one of the top 3 global destinations for motorhome holidays - but it's not cheap if you go as a tourist and hire a van. NZ has a massive fleet of vans for hire and hire vans easily outnumber home vans. The big hire companies are Britz, Maui, Jucy, Apollo and many others. Check out their websites - an average van costs around £2000 a month. For a 6 month stay this can cost £10 to 20k depending on the size of the van.

The way to do it on the cheap is to buy a van, and then sell it. This is only worth doing if you plan to go for the full 6 months you are allowed on a tourist visa. But if you are already fulltiming in a UK van and are a competent owner, you can do 6 months in NZ for about the same expenses as in Europe, plus the air fare, which is about £1000 per person.

The only problem with buying a van is that you have to spend time finding it, and more importantly you have to sell it again before your departure day, which can be stressful. The way to get round this is to buy from a small dealer and ask for a buy back deal. What we found with NZ folk is that they are basically extremely friendly and honest. Obviously there are no guarantees, but being in an English speaking country is a huge relief in this respect.

Our deal. We found a 1992 Nissan Civilian bus conversion with a ticket price of NZ$42,000 (£21,000). The dealer offered us back a price of NZ$37,000 in 6 months, subject to condition. We thought this was a stonking deal, and additionally we also really liked the guy - he was running a long established caravan and motorhome business and had a good reputation. This meant the van was going to cost us £2500 for the 6 months. We would have paid more!

We could have bought privately, but in retrospect buying from a dealer was just more convenient and easier. Selling privately would have been a stress, although we could have also chosen to buy privately and sell to a dealer for less money and still had a good deal. 

Next was the paperwork, unlike the UK, admin and paperwork is a dream in NZ. He let us use his address, and registration was done over the counter in a few minutes. Next was insurance. He recommended the NZ AA - and they have offices in all big towns. We just walked in and a very nice lady fixed us up with insurance and breakdown for NZ$60 a month, and we could cancel after 6 months with no penalty. UK driving licence no problem. In short, there is absolutely no problem for a UK visitor buying and running a van in NZ - it's easy!

The NZ MOT (COF) only lasts 6 months, the dealer did this for us.

Diesel in NZ is half the price of UK - about 75p a litre. However diesel vehicles have to pay Road User Charges - RUC - per kilometer. Our van was under 6 tons so we paid 7c/km. Even with this charge it still worked out 30% cheaper than UK.

All in all, the admin and paperwork side was a dream.

Next we joined the NZMCA - the national caravan and motorhome club. This cost $90, and the $200 joining fee was waived on production of our UK CMHC card. NZMCA have a network of member only sites all over NZ. You don't need to join, but we chose to.

We hung around the local area where we bought the van for a few days while we got used to it, and then we hit the road seriously. 

To kit out the van we used charity shops. Everything you buy in NZ will either have to be given away or sold at the end of your trip, so unless you intend to return, it pays to economise. Charity shops in NZ are called "OP Shops" and they are everywhere, and they are cheap! We got pots and pans and crockery and cutlery over a period of a week or so, and we had lots of change from £100. Bedding we bought on the high street for reasonable money. NZ has 4 big chains of stores for practical stuff - The Warehouse, Mitre 10 (like BnQ), K-Mart and Bunnings. NZ is not expensive - stuff is cheaper or at least the same, as in the UK.

You can buy stuff very cheaply and locally on Facebook marketplace. I bought a bike for fifty quid, and you can buy kayaks and fishing gear easily and cheaply.

There are 3 big supermarkets - New World, Countdown and Pak n Save - everybody has their favourite. Ours was Countdown.

Small grocery shops are called "dairies" or "superettes". There is also a network of small supermarkets called Four Square. Prices in these are more expensive than in the big town supermarkets.

In general food is roughly the same price, but better quality. There are some idiosyncrasies though. Meat and fish are half the price and twice the quality - lovely! The steak is to die for and cheap. But fruit and veg and salad in particular are double the price. We reckon it averages out. A frugal couple can easily eat well for £100 ($200) a week (no alcohol).

NZ fish and chip shops are amazing - half the price and twice as good. Fish and chips for 2 can be as little at £6 - a bit more in tourist areas.

Restaurants are pretty good - generally a bit cheaper than UK for the quality.

Booze is the same price as in the UK, but the wine is better for the same price. Good NZ wine is $10 a bottle. Beer is $1 a bottle. Whisky is $37 / litre. Tobacco is ridiculous - treble UK prices.

Camping sites with all the facilities average $40/£20 a night (for two persons). Many campsites charge by the person, not by the pitch, so make sure. Wildcamping is called freedom camping in NZ and there are plenty of places. There are 3 apps that list all the places - Campermate and Rankers. If you are in the NZMCA then they also have an app. There are also many other places you can stay and these vary from free to $5 a night to $10. Some are in the apps, other you get by word of mouth.

There are also DOC sites. Department of Conservation. These are government owned sites in areas of outstanding natural beauty. They cost $15 per night per person, and most if not all are just gorgeous. If these are the places you want to be, you can even buy a pass (not for the 3 week peak period at xmas) that gives you unlimited stays for about £100 - it's all on the NZ DOC website, and there is a discount for NZMCA members. These are the gorgeous sites that you see in all the magazine photos.

There is a good network of disposal points - called dumpstations in NZ. They are in all the apps. Most dumpstations have potable water - but not all.

Gas - gas is a dream in NZ. Everybody uses 9kg bottles. There is only one bottle and it can be swapped or filled anywhere. All big towns have at least one garage that fills bottles, or if not, you can just swap a bottle. It is really simple, not confusing like in the UK with competing companies and separate systems for refillable bottles.

Internet. Internet and mobile phone coverage is excellent, but there are areas of very low population that have no coverage. The coverage maps are online. In 6 months we probably had only 3 or 4 days with no coverage. The main networks are Spark, Vodafone and 2Degrees. SIMS are easy to buy. Prices are a bit more expensive than UK but affordable. Most UK networks roam in NZ, but not for the full 6 months. We bought local SIMs plus a data only SIM for our router. We use a lot of internet - most folk don't.

Health - we have been travelling for many years. Insurance is expensive. We chose not to insure. You get free emergency treatment in NZ no problem. Over the counter stuff is generally more expensive.

Driving is easy in NZ, very similar to UK, but with more of a USA and Oz flavour. The trucks are bigger, the roads are wider. Driving manners are generally good. Basically after the first couple of weeks it's no problem. No speed cameras outside of the cities, and patrol cars are generally a rare sight - you won't be speeding anyway! When planning your route be aware that gravel roads are very common, and often the only road to get there. They are fun, but the dust gets literally everywhere - it's almost impossible to keep out of the van. Make sure you know from your map and planning whether a road is tarmac or gravel - you can see 80% of NZ on tarmac.

Safety - we felt safe everywhere. The Maoris look a bit frightening with all their tattoos but we found them very friendly. NZ folk are in general extremely friendly and generous. However, according to Facebook, there is some crime, so take the same precautions as you would at home.

All in all, we reckon we did 6 months in NZ and spent approx £8k more than we would have done if we had done our usual 6 winter months in Europe in our own van. We think that was a bargain.

North Island or South island? South gets all the headlines - Lord of the Rings, mountains, Milford Sound, Fijords etc. It's the place to be if you like that sort of thing. But realistically it's no different to the Alps in Europe, or even Scotland. We chose the North - it is so varied - especially the volcanoes and the coast. We didn't regret our decision at all, although we did do a 2 week tour in the South in a car, before we went North to buy our van. Queenstown and that region has a reputation for being the most motorhome unfriendly place in the country. It is chock full of international visitors in peak season. Of course, in 6 months you can do both, and NZMCA membership gets you a big ferry discount. But we found North Island delightful. Our favourite place was the Coromandel peninsula - we stayed a month, and went back for our final few weeks.

Any questions feel free to email funkyronster@gmail.com and if the info is useful then please paypal me a bottle of wine to the same address. Cheers!

Turbo conversions on Mercedes Hymer motorhomes

I was recently asked about turbo conversions on pre 95 Mercedes Classic Hymer motorhomes, so decided it was about time to pull together all the info I have collected over the years.

These vans left the factory normally aspirated, but many owners back in the 1990s had aftermarket turbo conversions fitted. But are they any good?

I've owned vans with the German STT turbo conversion, with no intercooler, and also the TB Turbo conversion from the now defunct TB Turbos of Lancaster. I have also driven non converted vans, and hand on heart, there is a noticeable difference, but it's not huge, like you would expect from, for example, a turbo vs non turbo saloon car.

I finally had a very illuminating conversation with the owner of a specialist company in Lancashire called Diesel Bob. He told me that the problem with adding a turbo to these old Merc engines (the OM602 etc), is that they don't have ECU controlled pumps - just old fashioned mechanical pumps. So when you put your foot down and generate boost, there is no signal to the pump to push more fuel into the injectors to give the power. So while you do get a welcome extra kick from the raised inlet pressure, you don't get it's full potential.

The OM602 and its close relatives were the last generation of light commercial diesels before ECUs came in and direct rail injection - which is why from the 90s onward you could get a diesel car or van with a 2 litre turbo diesel that was almost twice as powerful and more economical than the old technology. In Mercs case this was around 95 when the Sprinters were introduced. The first generation Sprinter had 5 cyl engines based on the 602, but with factory fitted turbo and better pumps - they gave around 150bhp, compared with the 95bhp of the Hymer 602 engine.

The turbo conversions came about because by the time you had bunged a 6 or 7 meter high quality Hymer body on a 410D chassis rated at 4.6t, what you ended up with was a light commercial vehicle that basically spent its life fully loaded, at around 3.7 to 4.3 tons, depending on model and payload. Even by the standards of the day they were underpowered, and slow. But they were also the top of the range vans of the day in Germany - around 100,000 Dmarks, and buyers were well heeled, so thought nothing of splashing out on a turbo conversion offered by the dealer.

Unfortunately - and it is a question that is asked regularly - there is no easy way to do a similar turbo conversion today - both STT and TB are out of business, and more importantly, the custom exhaust manifolds onto which the turbos mounted are no longer available. The only alternative is to have a custom exhaust manifold made by a specialist company. A few people have done it though, so I have heard over the years. Of course there are motorsport outfits that would do it, but it's also a question of money. The guys that have done it are usually in the motor trade and DIY. It's a fair amount of labour, plus parts, and at commercial rates of £50+ per hour I reckon a custom turbo conversion would cost around £5k or more.

But for the power hungry there are alternatives. The first is to re-engine with a donor engine that is factory turbo'd. Donor engines are either from first generation Sprinters or the Ssangyong Musso from the 1990s - a 4x4 car that used the Merc 5 cyl engine under licence. I know of at least 2 guys that have done this, but it's quite a job because the Hymer engine compartment is quite tight.
The second, and quite recent, option is to fit an uprated diesel pump. The OM602 (and its brothers) engines were fitted in early Merc G Wagens, and there is a healthy industry in customising and uprating these. Also, for some weird reason, Merc saloon cars of this era are favourites for fans of "drifting". There are 2 firms that specialise in this - Dieselmeken in Sweden and DieselPump UK here in the UK. Both have informative websites, and both claim to offer an uprated pump that will up-rate a 602 to 150, 200 or even more BHP. The cost is reasonable - around £1500. I know of 2 UK Hymer owners that have done this. The only slight reservation I have about this though, is the effect on the rest of the van - the drivetrain and cooling systems, of suddenly upping the power to 150bhp, and purists will also point out that brakes should also be upgraded to cope.

Edir 2020 - here is a very interesting Youtube from DieselpumpUK - the engine is a 617 - similar to the the 602. It's a good fun watch!

https://www.youtube.com/watch?v=tfvzwWP0WXE

Another issue is that the gearboxes on Merc Hymers are quite low geared, so even if you had power to spare, it would only be useful on hills - you wouldn't get much extra top speed cruising because the engine would be at its rev limit. Some owners have changed their gearbox to a higher ratio version - myself included. It's a straight swap, if you can find one, and the result is that you lose the low crawler gear and get a higher fifth gear, and thus lower revs at high speed. It's still useless on hills though.

There is also another school of thought that says - why bother! Trundling along at 55 is all part of the fun! This is also the point at which owners of Fiat family engines start to crow - Fiat were earlier to the market with stock turbo engines, and there is no doubt that the turbo Fiat engines of the same era, in a similar body weight, are more powerful.

Finally it also must be said that anybody who is disappointed with the power of their Merc 602 based Hymer - usually S660 and S700 owners - the heaviest - should first ensure that their fuel delivery system is in tip top condition. There are at least 3 filters between the tank and the injector pump, and as most vans are now in the 20 to 30 year old age bracket, these items can get clogged with age. I have seen many a story online where a sluggish van eventually started to give up the ghost - usually on long hills, and all it turned out to be was either a clogged fuel lifter in the tank, the inline filter, or more rarely the main fuel filter. Once these have all been attended to, a van can spring to life in a very satisfying way. There is no point in contemplating power modifications until these items have been checked and serviced.
Sorry this reply has turned into a bit of an epic, but I have been meaning to write this up for quite a while as it is a regular question. I shall turn it into an article for my blog and for this group also.

If you google "Hymer Mercedes turbo conversion" or similar, you will get hits from many forums going back years - it's been quite a hot topic over the years, and unlike Facebook, all the old archive stuff on the forums is still available and searchable with google.

EDIT NOV 2020 - There is now a dedicated Mercedes Hymer engine upgrade Facebook group.

https://www.facebook.com/groups/846310116138685

How the water system works - pumps and microswitches.

I have seen a lot of questions recently about the water system in Classic Hymers.

Here is a rough description of how it all works - remember we are usually talking pre 95 vans, and different vans have different layouts. Also remember that in any old van, previous owners may have made modifications.

There are 4 main components to the basic water system - the fresh tank, the pump, the pipes and the taps. 

The original system is what is called a switched pump system. This differs from a house system in that it is not pressurised. In a house, the mains water is under pressure, so all you have to do is open a valve (a tap) and out comes the water.

In a switched system in a Hymer, there is a 12v pump submerged in the water tank. The pump is attached to a pipe that leads to all the taps. Each of the taps has a switch in it, and these switches are connected to the 12v battery system in the van. Every time you open a tap, not only does a valve open, allowing the water through, but the switch closes and supplies 12v to the pump so that the water flows. When you close the tap, the pump stops.

The reason they do this in motorhomes is that it is less risky to the van if there is ever a leak. If a pipe bursts, or leaks, or there is a loose connection in any of the pipes, the leak is limited to the amount of water in the pipes, and the whole tank will not empty into the van. This helps to prevent catastrophic leaks that can lead to expensive rotten damp damage. Of course it is not totally foolproof - if there is a slight leak that only drips a few drops every time a tap is operated, this can also lead to damp and rot damage. So in an old van, ot pays to regularly inspect your water system.

The switches inside the taps are usually called microswitches. If you look at the underside of a tap, you will see the water pipes going to it, and also 2 wires. In  some taps, these microswitches can be replaced - see picture below for a typical example.

If you do not hear the pump operate when you open a tap, and no water flows, then that is usually a sign that the microswitch isn't functioning. This can either be the switch itself which needs replacing, or the wires to the switch have come loose or damaged.

Another reason is that the pump is broken, or the wiring to it is broken or corroded. See troubleshooting common faults below ...

An idiosyncrasy of the system is that any tap will operate the pump, so if you have a broken switch in one tap, you can still get water out of it by opening any other tap. For example, if your shower tap isn't working, just opening another tap slightly, just enough to make the pump run, will enable the water to flow from the shower.

The next component after the pump is the manifold. A single pipe runs from the pump in the tank to a distribution manifold. This looks like a tube that has several pipes coming from it - see picture. It enables a single pipe to be split into several more pipes. In a normal setup, there are 2 manifolds, cold and hot. The cold feed from the tank goes to the cold manifold, and from there there is a cold pipe to each tap - usually kitchen, bathroom and shower. In some vans the bathroom tap and shower is a combined unit. From the cold manifold there is also a feed to the Truma hot water boiler, and then the hot water from the boiler goes to the hot distribution manifold, and from there hot pipes go to the taps.

On some older vans there are no manifolds - there are just a succession of T joints, which achieves the same thing - distribution. So if you don't find a manifold in a pre 1990 (roughly) van, look for T connections.
 
There are usually also 2 drain valves, one in the cold side and one in the hot side - both usually adjacent, and connected to, their respective manifolds. The cold drain valve usually has a metal body and a red or yellow plastic handle. This is to drain down the entire system for winter storage. The hot drain valve is grey plastic and looks quite different - to open it you unscrew the top. This will drain down the hot side of the system and is useful when you just want to work on the boiler, for example.

To drain down a van for winter, drain the main tank, isolate the pump - usually by switching off all 12v to the van with the big red isolation switch - open all the taps, and open the main drain valve. All the water in the tank and system should then drain onto the floor and the pipes should all be empty, and not prone to frost damage. Some main water tanks have drain plugs, which makes draining quicker and easier.

Then leave all the taps open and the drain valve open for the winter. Don't forget to close it before you fill up in spring, and it is always a good idea to check every joint for leaks and drops at the beginning of a new season.


Post 95 vans often have 12v electrically operated valves with thermostatic control - they will automatically open in a frost. After 25 years these get unreliable and are often replaced with manual valves, or held closed with wire or cable ties. But pre 95 classics have manual valves.

Taps - Usually in Hymers and most motorhomes, the taps are mixer taps, rather than individual hot and cold. A mixer tap has both hot and cold pipes leading to it. There are many types of taps - too many to list individually. Some taps have red and blue plastic push fittings, others have normal spigots and jubilee clips.

Modifications

A  popular modification is to fit a manual pump switch. This is a simple switch, mounted anywhere convenient, that will supply 12v to the pump when the switch is operated. This is in addition to the tap switches, which continue to operate normally. An extra switch is useful because it will allow you to use all the taps if a tap switch breaks - saving you the inconvenience of opening another tap just a bit to run the pump. Also useful if you have an outside shower modification. You switch on the pump before you need water, and then off again afterwards. But you must remember to switch the pump off afterwards - which is usually no problem because you can hear it.

Many long term owners or full timers do this because they get tired of changing tap microswitches - it is a fiddly job. There is nothing bad about the design, but realistically they were never expected to have to last for 30 or 40 years.

Common faults

As already mentioned, the commonest fault is a faulty microswitch. You may be able to replace the switch. Sometimes owners take the opportunity to replace an old tap with a new modern one. The modern silver Reich single level mixer taps are a common choice.

There are too many different taps for specific instructions, but here are a few guide notes. Look for "tails" many taps have factory fitted pipe tails, and it is the tails that connect to your pipes. Other taps have push fittings - so if you see no jubilee clips or other fixings, and wonder how on earth the pipes are connected, then get a grip and pull. Google for "caravan taps" and you will see lots of pictures. Most taps are secured to the sink by a large plastic nut. You may think - how on earth do I get a spanner on that - usually, you don't have to - it will be only finger tight. It may be stiff with age, but do your best to exert maximum force with your fingers before giving up!

If your switches are OK, and the pump is not running, then the pump, or the wiring to it, is suspect. The thing to remember about the original submersible pump, is that they are not intended to last for the life of the van - in effect they are a consumable. They rarely last more than 10 years in regular use, and they often can, and do, fail, especially after a long period of storage. But they are cheap - every caravan shop sells them, and any 12v submersible pump will do, from a cheap single barrel Whale, up to a Reich double barrel costing over £60 ... Most owners carry a spare, but they are easily available in all countries.

But before you buy a new pump, here are some tips to revive an old pump. They work very simply - a small 12v motor turns an impeller. Similar to a fish tank pump. The impeller can get stuck. if you have easy access to your tank, and can get your hand inside, reach into the water, grab the pump (with power applied by an open tap) and give it a good shake and knock - this will often free the impeller. If this doesn't work you can take the pump out and try again in the dry =- you may find the input chamber is gunked up.

Wiring. The wiring of tap switches confuses many people. It should never get disturbed, but occasionally you might get a corroded connection. The taps wires are fed from a connection block with spade connectors on the ends of the wires. yes they often look like spaghetti, but there is a totally logical layout. 12v pos is fed from the connection block to each and every tap, and the return from the tap goes to a single connection, to which the pump positive wire is connected. The pump negative wire comes back from the pump and connects to a brown negative connection. So when any tap is opened, the switch closes, and 12v is allowed to flow from the connection block, to the tap, through the closed switch, back to the connection block pump connection, to the pump, which runs, and back to negative ground via the block. When the tap is closed, the tap switch opens, the circuit is interrupted, and the pump stops.

Unfortunately the spaghetti at the bathroom toilet block is made a bit worse by the toilet connections. The toilet flush is a simple switch like any other - it turns on the pump, but the toilet also contains a solenoid valve which is operated by a relay, and the relay also needs its own 12v feed. So the toilet needs 4 wires - flush switch supply and return, and 12v pos and neg to the relay.

It should also be said that the van model and layout dictates where all this wiring is located - but the electrical principle is always the same - a 12v source is led to a switch, and then to a load, and back to ground.

A common question is - "which way round do the wires go when fitting a new tap microswitch"? The answer is - it doesn't matter, the tap switch circuit is not polarised, so it will work either way. But please note this only applies to switches, not the rest of the van, where polarity is very important!

It is all easily troubleshooted with a logical approach and basic multimeter skills. But electrickery confuses most owners! 

A typical connection block.

This diagram demonstrates the principle.

The next commonest fault is a leaking manifold. The original plastic Hymer manifolds are subject to a lot of vibration over 25 years of travelling, and eventually they are known to develop cracks. Many a rotten floor has been caused by a leaking manifold, so it pays to inspect your manifolds regularly. If you do find a leak, you have several options. You can buy a new manifold from Hymer or any spares supplier. The new manifolds are stronger, but they are not cheap. Many owners make their own manifolds. There are several ways to do this - all you need is a method to join 4 or 5 pipes together. Popular choices are compression "T" fittings, or copper fittings. See pictures. As long as it is strong and watertight, you can use whatever method suits you.

Manifolds can also suffer from calcium deposits that build up over many years which can result in reduced flow. This is dependent on the hardness of the water regularly used to fill the tank. if you live in a hard water area and regularly have to descale your kettle, and you regularly fill up the van with the same water, this can happen. manifolds can also get clogged up with other debris.

The way to check if a manifold is in good condition is to identify the main feed to it. Then clamp of the pipe and undo it from the manifold. Then, with the pump running, release the clamp and let the water flow into a bowl or old towel. if the flow is strong, but the flow coming from the taps was weak, then the manifold is suspect. But if the flow is weak, then the pump is suspect.

Also, usually close by the manifolds, or close to the Truma boiler, you will find a drain tap. This usually leads from one of the manifolds and is a tap valve mounted on the floor. It has a lever on it to open or close it. This is the drain valve, and is used to drain down the system for winter storage. Draining for winter storage minimises the potential for frost damage to the pipes.

The waste water system - also called grey water.

Water that goes down the plug holes flows through grey waste pipes. These are slightly bigger than the water feed pipes, and they are different in that they are rigid pipes, joined together with push fit elbow joints. They usually are arranged in 90 degree angles. Under each plug hole is usually a trap - same concept as a domestic U bend, but these are usually round traps with concentric circular chambers that fulfil the function as a U bend, only in a more compact format. these are usually made by Reich. These traps are susceptible to clogging with old age - they get full of grease and gunk and old hair. 

These traps are serviceable. They can be removed by pulling off the grey waste pipe and then undoing the central screw in the  plug hole. They have a circular cover on the underside that can unscrewed revealing the insides. WARNING! Removing and servicing a trap can be fraught with difficulties and gotchas. They can get very stiff with old age - removing them can break or crack the hole in the sink. Very often when you screw back the cover of the trap, and the trap itself, you don't get a good seal and you will get a leak. It can be an extremely frustrating job, so my advice to you is not to take it on unless there is no alternative.

If you have a blocked or slow trap, try everything first before removal. If you do remove, be ready to order a new trap - it might be the only solution, so remember this if you are on holiday. Try boiling water, chemicals or gentle plunging. Trap removal should be a last resort, and only then if you have the skills, time and spares to deal with the job going wrong.

From the trap, the plastic waste pipes lead to the waste tank. As already mentioned, these are straight lengths of plastic waste  pipes joined with 28mm compression elbows. These elbows are prone to splitting and leaking, and again, benefit from regular inspection. There are no junctions in the waste pipes - they lead individually from the sinks/showers directly to the waste tank, where they enter into the top of the tank through elbows and big rubber grommets. The place where they do this is usually accessible, usually underneath a wooden panel. Another common fault is that many years of vibration can work the joints loose, resulting in leaks. They can also split with vibration and old age. Split elbows can be repaired using modern sealers and plastic glues. If using sealer to repair, the mating surfaces must be super clean. 

But please don't panic thinking that the system is unreliable - leaks are quite rare. All you have to do is to use common sense. 

Maintenance

Just as you maintain the rest of your van, it pays to maintain and check your water system, because leaks can cause expensive rot repair bills. All you have to do is keep an eye on things. 

Taps - every few months, put your hand up under the tap where the pipes attach, and feel for water. Same for the traps and waste pipes - obviously you can't get at all of them, especially the shower trap, but know your van, and take a regular look.

Everybody cleans out their boot or storage area occasionally - when you do, check for wet patches. Also - know where your manifolds are, and check regularly for leaks.

Another tip is to wait until somebody is having a long shower and look under the van for any tell tale drips, especially in the area of the shower tray and the grey tank. Do this once or twice a year.

Pump. Carry a spare!

Pressure Systems

Some owners decide they want more pressure than a submersible pump can provide. So they convert their water system to a pressure system. This is similar to the system used in yachts and boats. In a pressure system the submersible pump is discarded, and replaced by a simple pick up in the tank. The pump is then mounted externally to the tank. Popular pressure pumps are made by Shurflo and Whale. A pressure pump switches on when the pressure drops - ie a tap is opened, and switches off when the pressure increases - ie a tap is closed. This means that the entire system is permanently pressurised, just like in a house.

Advantages. Higher pressure - much higher than a submersible pump. Better showers.

Disadvantages. More prone to leaks, and when leaks do occur, they can be serious. Because the original van pipe system was designed for a low pressure system, and in the case of an old van - is old ... then suddenly increasing the pressure can result in new leaks occurring. So in the days and weeks after upgrading to a pressure system, all joints, taps and manifolds must be inspected and tightened if necessary and checked for leaks. This is not to say that the pipe and tap system is not suitable for higher pressure - it is, but it needs to be checked in an old van.

The other problem is that if a leak does occur in a pressure system, the pressure will drop, and the pump will operate - usually in small pulses. If the van is unattended, then the entire tank can be emptied through the leak, which isn't good. For this reason, pressure systems should have an isolation switch which cuts power to the pump, and the pump should be switched off when the van in unattended.

However, the upside of this, is that of you do develop a small undetected leak, the pump will pulse occasionally as the pressure drops, giving you warning. The pump will occasionally pulse randomly, but if it pulses regularly, say every 15, 30 or 60 minutes or so, then that is a sure sign of a dripping tap, or a leak.

Another thing to consider with a pressure system is that you will use more water. This can be an issue with showering, as too big a flow rate may empty your 10L hot water tank before you have finished your shower ... so there is a balance to be made.

Hybrid pressure system

You can add a pressure switch to the original tap switched submersible pump system. This is an inline water pressure switch with an electric switch. This sits between the tank pump and the manifold - usually on top of the tank but can be installed anywhere convenient between these two points. A pressure switch monitors the pressure in the water feed pipe. When a tap is opened, the pressure drops, the switch closes and supplies 12v to the pump. When the tap is closed, the pressure starts to rise again, until the switch opens and the pump stops. This is a way to convert to a pressure switched system without having to replace the pump. The advantages and disadvantages are exactly the same as the pressure pump modification detailed above, except that water pressure remains the same as before.

Finally a few random notes.

If you get black stuff in your mixer taps - this is a harmless bacteria. You can treat it with Elsil. 

Owners often ask if they should drink the tap/tank water. Other than making sure that the water is fresh - ie not from last summer! Then my answer is yes. There is no reason for your water system to be any worse than the mains pipes that deliver to your house. You may detect a plastic tinge from the tank. But basically it's up to you. I use it for tea and coffee, but for drinking water we refill containers with tap water. However, if necessary, I have no problem drinking it, and have done so for 20 years in many countries. You can buy filter systems, but I have no experience of these.

Manifolds - top one (hot) is a Hymer original. Bottom one (cold) is a home made copper one. You can also see the hot system valve at the top of this manifold.

Another example of alternative, stronger manifolds - these made by Snailvans in Leicester I believe.

Drain valve - also available in red!

A new Reimo manifold - not cheap!

Typical Microswitch

Typical modern mixer tap - many other designs available

A typical external 12v pressure pump

This is a popular type of pressure switch - this one made by Whale

A typical standard submersible pump

Typical tank layout
The pump is submerged under the orange hatch. Black hatch is for inspection/cleaning - it can be other colours.

A= Main feed pipe to water system (taps etc) with non return valve to stop system siphoning back

B= Tank venting to allow filling without blow back at filling point 

C= Non return valve allowing air back into the pump allowing it to drain and be frost protected when the tank has been drained. 

Typical concentric odour and waste trap - one end is usually blocked off, and in Hymers they are usually white. 

Waste pipe elbow - occasionally prone to splitting with old age.

Turning fridges upside down - The truth about the myth.

The following information is not my personal opinion, it comes from a well respected industry professional.

I have lost count of the number of times I have seen online people advising to remove a 3-way fridge that isn't working properly, and invert it or rotate it. 

The reason this myth perpetuates is that very occasionally it does work, but only occasionally, and to actually work, it must be done in a certain way, and only under certain conditions. If it is done the wrong way, it can actually finish off a fridge that otherwise might have been saved.

The first thing you have to check is this - if the fridge works OK on 220v or 12v (while driving), but not on gas, then rotating it or inverting it will not solve anything, and may finish it off completely. If the fridge works on any one of the 3 power sources then that means there is nothing wrong with the actual fridge cooling mechanism, and therefore it should not be inverted or rotated.

There are 2 reasons why a fridge may not be working on any power source. The first is that the chemicals inside the tubes may have separated, usually through old age and not being used very often. The fix for this is vibration, not inverting or rotating. The best way to vibrate a fridge is to find a cobbled road or rough track and take the fridge for a rough ride. This has been proven to work on many occasions. 

The second reason is that in an old fridge, the pipes and tubes that contain the chemicals may have corroded internally and bits of corrosion have blocked the evaporation venturi. This is a small hole in the piping system through which the chemicals are forced as part of the cooling process.

And this is what gives rise to the myth - if this hole is blocked by internal debris, and the fridge is rotated the right way, then there is a chance that the debris will be dislodged. But if rotated the wrong way then even more debris may be forced into the hole, making the blockage even worse and possibly damaging the fridge beyond repair.

The only time it is advisable to rotate the fridge is when you are sure that there is a working heat source, yet the tubes at the top of the fridge do not get warm, and you have tried upright vibration. Then it is essential that the fridge is rotated in the correct direction, so that the rotation pushes any debris AWAY from the hole, rather than into it. And even then, this method has only an approximate 1 in 4 chance of success. If rotated correctly, no further damage will be done. But if rotated the wrong way, then the problem could be made worse. After rotation, before re-installation, put the fridge on 220v on max, and see if you have been lucky. If not ... it's usually time for a new fridge.

So which way is the right way? As you look at the back of the fridge, with the chimney on the right, it is anti-clockwise. Rotate the fridge (2 person job) smoothly as you can 3 or 4 turns anti-clockwise.

It must be stressed that this is a last resort, and only has a low chance of success. But occasionally it does work, and this is what has given rise to the online meme that is increasingly being advised for just about any fridge problem.

I have also been told about another method to try and revive an old fridge. Run it on 220v AND gas at the same time, with the thermostat on full. This extra heating is often enough to remix the chemicals and get things working again. Whether you can do this easily depends on the model - some fridges have controls where you can run on both at the same time, others don't. If not, you have to manually hot wire the 220v element around the back so it runs while on gas.

The commonest problem with old 3-way fridges is "not working on gas". The usual reason for this is lack of maintenance and cleaning. The gas part of the fridge is far more prone to failure than the electric part. The electric part is just an element, similar to a kettle or immersion heater, and it either works or it doesn't. The same goes for the 12v element.

So the first thing to do with a fridge not working on gas, is to connect it to 220v and turn it up to max. The chimney and the pipes should get should get hot. If not - the 220v element is suspect, and should be checked.

Only if there is heat from the 220v element, but no cooling, should you then consider removing the fridge and vibrating or rotating it.

If the fridge works fine on 220v but not on gas, then there is no point in removing, vibrating or rotating, and the good news is that gas problems are usually easy to fix, either by the owner or a professional, and at reasonable cost. 

The commonest problem is dirt or dust obstructing the gas jet - there are plenty of articles and Youtubes online on how to clean the burner and jet.

Fridges don't last forever - but many last for 25 years or more, which is fantastic compared with normal household appliances. Just don't finish off an otherwise fixable fridge by believing everything you read online. Removal, inversion and rotation is a last resort, after everything else has been tried, in a logical manner.