Truma 3002 fire won't light? Truma ignition problems?

Most classic Hymers have a Truma 3002 - the heater with the brown front panel. One of the commonest problems is that it works perfectly for years, then suddenly stops! When you push and turn the knob, you should get that familiar tic tic sound - if you don't, then it's usually an ignition problem. Two things happen when you push and turn the knob - turning it operates a small switch that switches on the ignition unit - that makes the tic tic sound, and pushing it opens the gas valve to the pilot light. Once the pilot light is lit, the thermocouple inside the burner operates, and allows the gas to keep flowing when you release the knob. If you release the knob too soon, then the thermocouple doesn't have time to heat up and the pilot light goes out., The basic operation is just like lighting the cooker.

Once the pilot light is lit, if you continue to turn the knob, the main burner will ignite with a familiar whoosh. The point on the knob dial that this happens depends on the ambient temperature. If you open the knob fully to a high setting, then you will usually get both the pilot and the main burner igniting together.

There are 2 problems that can happen at this stage - either no ignition at all - ie no tic tic sound, or the pilot lights, but the main burner doesn't.

No ignition


The way the ignition works is that at the lower left hand side of the fire, when you take the cover off, is a small plastic box about the size of a cigarette packet. This is the ignition unit. Usually it has a single or double AA battery in it, but not always. Some vans don't have the battery - the box is supplied with 12v from the van supply. Either way, you need to make sure that the box either has a good battery, with clean battery connections, or a good 12v supply. The battery supplies power to the ignition unit which transforms it into a pulse of electricity that produces a spark at the electrode in the burner - just light the spark of a cigarette lighter.

At the back of the ignition unit, there should be a single wire coming out of the middle of the back. Make sure the knob is in the off position and pull this wire off. If you now turn the knob on as if to light the fire. The box should tick - if it doesn't then the box is suspect. The wire is called the HT lead - it carries the pulse of power for the spark. It gets worn and brittle with age, and its insulation breaks down. Sometimes it breaks completely, other times it sparks to the metal chassis - sometimes you hear a muted tic tic, but either way, the fire won't light. So first you need to know you have a working ignition unit - make sure the battery is new, and the connections are good. Be careful - if the unit tics to your fingers you will get a shock, not fatal, but no fun either. Always make sure the knob is OFF whenever you go near the HT lead with your fingers. With no HT wire connected, the box should audibly tic when you switch on the knob. If it does, then you know you have a working ignition unit, and the problem is with the HT wire.

The other two wires from the ignition unit go to the rotary switch that is located at the bottom of the long shaft of the control knob. As the knob is rotated from the zero/off position to the on position, you should hear a gentle click. This is the switch that completes the circuit of the two wires that go to the ignition unit, and it should start ticking (with no HT wire connected). This doesn't often fail - but as there are 3 possible points of failure - you have to be able to eliminate each one. If you get no audible tic tic from the ignition unit, then it is definitely suspect, but you also have to eliminate the (rare) possibility of a faulty switch. You can do this by pulling off the switch wires and touching the two pins together with the tip of a screwdriver - this completes the circuit and the unit should tic.

Non ignition is usually always the battery, or dirty battery connections, or dirty connections on the ignition unit. But if you have a good tick from the ignition unit (with no HT wire connected) then it's likely to be a damaged or old HT lead, and unless it's sparking to chassis in the section before it goes down into the underside of the fire, then the only solution is to take the fire out, exposing the underside where you can see the rest of the HT wire leading to the burner. Usually, if you are sure the ignition unit is working and ticking nicely, you will find that the wire is either broken, or corroded, or the insulating sleeve is broken and it is sparking to the chassis. It is possible to repair if you know what you are doing, but usually it's best to replace the whole HT wire with a new one from Truma spares. Taking the fire out isn't actually that complicated for a confident DIY'er with a decent tool box, but can only be recommended with a whole bucket full of warnings about gas safety - you will have to be totally confident about breaking the gas supply, and then leak testing on reconnection, and you have to be quite sure that you have reconnected the chimney pipe, with its silicone gasket ring, perfectly, as well - otherwise you risk deadly fumes leaking into the van. So basically for most people, at this stage, you need a qualified Truma guy, unless you are sure it's the ignition unit, in which case this can be replaced DIY with no safety issues.

But it's nearly always the battery, or a faulty 12v supply, or dirty connections around the box - but if it happens to you, you should be able to narrow it down. It's embarrassing and expensive to pay a professional, when all you needed was a new AA battery, and to clean a few connections.







No main burner ignition

The other common fault is that the pilot light lights, but the main burner doesn't. The Truma heaters are unusual in that the pilot light is big enough to provide a reasonable amount of heat - it is basically a low setting.  On a fully working heater, as the thermostat cuts in and out as the ambient temperature rises and falls, the heater changes from low setting (pilot only) to high setting (main burner). You will hear the familiar whoosh, as it does so.

The commonest reason for the main burner not to light is a sticking gas valve. If you take off the front of the fire, you will see that the main control knob is connected to the main gas valve by a long control rod. The bottom end of this control rod locates in a recess in the top of the shaft of the main valve, allowing it to be both pushed in, and rotated. The shaft is spring loaded, allowing it to spring back when pushed in. What happens is that after many years, it gets full of dirt and dust, and gets stiff. A common cause of the main burner not lighting, is that this shaft is not springing back fully, and is not allowing the main burner gas valve to operate. The remedy is to clean and lubricate it as best you can, and work it up and down so it presses in and returns fully without sticking. You can use WD40 or silicone spray - anything that works really, but preferably something that doesn't attract more dirt. Common sense is the best ingredient.

Over many years of operation you may notice that when you light the fire, the knob often springs back quite slowly after you release it - this is a sure sign that it is dirty and needs a clean.

Another reason for the main burner not operating is a faulty thermostat. This is the copper tube thing at the bottom right. This is connected to the main gas valve by a thin copper tube. As the temperature rises and falls, liquid inside the tube expands and contracts and operates the valve. It is a sealed system and not serviceable. The copper thermostat and the gas valve have to be replaced as a complete unit, and is basically a professional job.

Boatyards make good pitstops

RONS TECHNICAL TIPS NO - "AHOY THERE!"

Caravan and Motorhome repair and accessory shops can be few and far between when you are in far away places (or Scotland!). 

But don't forget that boats use many of the components in our vans - or very similar. Boatyard people also will have the skills and understanding to try and help you out.

So if you are near the coast, or a big lake - a lake big enough to have plenty of boat activity - then head for the nearest town and search out the local boatyard. They always have bits and pieces - "chandlery" and fibreglass skills.

In the UK, and countries like Holland, Germany and France which have extensive canal networks, you will also find boatyards and repair places inland - so check your maps for canals.

In an emergency there is a good chance that a boatyard can sort you out or effect a running repair. They will also know the best local places for diesel work - most boats have diesel engines.

Just don't park on the slipway - especially if it's green!

Fixing a broken blind.

The plungers that you squeeze together with your fingers, to operate the blind, have a plastic pin which locates into a hole in the slider. The pin shears off the body of the plunger, so no longer moves the slide - technically it's a weak design, although not many actually break, we get a couple each year. The solution is to either buy a cheap blind from a breaker and cannibalise it for parts, or you can repair it. Basically it needs skills similar to model making. The usual approach is to take it apart and then locate where the pin used to be. Then drill a hole in the plastic and glue in another pin. You don't even need glue if the pin is a good fit. This could be a bit of broken drill, or a small "seloc pin" also called "roll pins" from a model engineering shop, or anything that your ingenuity can come up with. It's only the equivalent of a finger in a hole! The bad news is that you have to disassemble the whole blind just to get at it. I once spent hours of my life that I will never get back thinking that I could drill a hole from the front and then insert a screw so that the tip would locate in the hole. The trouble is that you don't actually know where the flipping hole is, so it's guesswork and easy to ruin the whole thing. So easier to just bite the bullet and disassemble. You then can see exactly where the hole needs to be drilled because there is a mark where it used to be. 

If you look for spares from a breaker, then you need to know that the blinds are made by a company called "Seitz" - "the ones from 20 years ago that you squeeze together to pull them up" - most breakers should know what you mean. It doesn't matter what size blind it comes from, as the part is the same on all blinds. It is unlikely that you will just be able to buy the part - most breakers will charge you for the whole blind. The going rate (2016) is around £30 a blind. If you have a choice, buy a blind bigger than yours, then you will have spares that can be cut down.

Have fun!

USING A TABLET INSTEAD OF A DEDICATED SATNAV

RONS TECHNICAL TIPS NO "WHERE AM I?"

USING A TABLET INSTEAD OF A DEDICATED SATNAV

People seem to like dedicated satnavs, but even the cheap ones are expensive. I use an android 7 inch tablet - you can get brand new ones for £69, and s/h ones for buttons, and I run TomTom for android which costs £15 a year. The latest version of TT is really very good - not perfect, but very good. You don't need a connection to the internet, but if you do, then the traffic information is really excellent, and because the screen of the tablet is so big, it's a really nice display.

The icing on the cake with this solution, is that you can use the tablet for other things. Mine is basically setup as the vans mission control. It is mounted on the dash and isn't used for anything else - it lives there just like a dedicated satnav. In addition to TomTom I have the Wildcamping app, Google maps, and I also have the entire UK set of OS maps, which isn't cheap, but worth it for me. Because mine is always connected to the internet I can do research, messaging, facebook - anything I want really, and all from the drivers seat, while doing 90mph in the outside lane operating the phone with one hand and a beer in the other while steering with my knee. Obviously.

The Wildcamping app is particularly cool if your tablet is internet connected, the map displays the nearest spots, and with a single press it fires up Google street view and displays a photo of the wild spot.

Having Google Street View at your fingertips while on the road is also incredibly useful - saves having to get the laptop out or squint at the phone. As an example, I use it to check if there are any height barriers at shopping centre car parks. The only problem with it is that you have to put the beer down in order to operate the tablet. 

If you buy the right tablet, and spend a bit more on one that has a sim socket, so it basically becomes a big mobile phone, and then shove in one of the cheap PAYG data sims from Three or EE, not only will you get real time traffic info from both TT and Google, you can use the personal hotspot feature of the tablet and provide wifi in the van for all your other devices. It is worth remembering that a tablet generally has a better antenna than a phone or a little mifi unit, and when mounted in the clear at the front of the van (see photo) will generally get a better signal in remote areas. Not as good as a dedicated external antenna, but better than a small phone.

So basically a dash mounted tablet/phablet is a very versatile jack of all trades and much cheaper than all but the cheapest Chinese sat navs.

I am very picky about satnav, and have tried them all except Garmin. I must say I am very quietly impressed with TomTom for android. It updates itself and is pretty much always up to date and maintenance free. I am more than happy to pay their reasonable annual fee.

Apple users can achieve all of the same buy buying an old Ipad mini, but unfortunately it has to be one with a sim card, because only the sim card Ipads have GPS. You don't need to have a sim in it for it to be a decent sat nav, but having a data sim in it, or tethering it to a phone will give you TomTom's traffic info - which is rather good. Most Android tabs have GPS - but do check.

Mine is mounted with Velcro, and fed power from a USB socket on the dash, and can be removed in seconds for security.

Finally - I was joking about the beer and operating while driving. They have now doubled the fine and points for operating a device while driving, so even I am now behaving myself, after years of knee steering I now have both hands on the wheel! It's weird! Mine is set up so that while driving it only needs a glance, and the voice instructions are really good. I even have it set up so that I can voice control it - I can say "Hey Google, navigate to the nearest Tesco", and it works. But usually it's just easier to do all the research and set up the journey before driving away. And of course your copilot can also do all the button pressing while you are driving.

I am not saying this is the best way to do things, but it is my favourite solution in my van. It isn't particularly technical, and quite easy to set up. Even if you only use a tablet for satnav - you still get a huge screen for very little money.

TomTom

OS Maps from Viewranger app

Wildcamping app

Photo view of wild camping spot

I have now also added a second tablet to cover the speedo. The app is called DigiHUD Pro, available from the Android app store.

INTERIOR CLASSIC LIGHTING 101

I have seen various posts and questions over the years about the various interior lights in classic Hymers. Changing to LEDs has been all the rage recently, but for many this is at odds with preserving the classic style, and for others they just don't like "colour" of the new LEDs. Add to that the fact that some fittings and bulbs are getting obsolete and hard to find so it's no wonder there is confusion. So let's clear it up.

In an "average" classic Hymer there are 3 types of light - tube, halogen and incandescent. There are photos below of the common types. 

Tubes. These are easy to identify - they are long and thin, and are mini versions of the fluorescent tubes us baby boomers all grew up with at home and work. They work on the principle of trapping a fluorescent gas inside a vacuum tube, and applying voltage at each end. This causes the gas to glow and give out light. They were "new technology" once upon a time. For many years the only type of domestic light was the good old fashioned lightbulb, but these were very inefficient, giving off only about 20% light and 80% heat, so when fluoros came along, giving off more light and less heat, they became instantly popular, especially in the workplace and in institutions - ie hospitals! They give off quite a harsh bright white, which is great for brain surgeons, but not so good for the bedroom. So fluros tended to be found in utility areas, kitchens, garages etc. However it was possible to get a softer light from tubes by using shades and covers made for glass or plastic, and this is what we find in our classic Hymers - a white tube covered by a smoked plastic cover, and the result is a reasonably pleasing light for the van interior.

Tip - when did you last clean your tube shades? Most classic tube lights in Hymers have 2 thumb screws that enable you to easily remove the shade. A good wash can make a big difference if yours haven't been cleaned for many years.

The tubes themselves are still easily available. They last a very long time, so many of us still have the originals and are unfamiliar with changing them. They can blow suddenly, or gradually. The sign of a tube on the way out is they go black at the ends and occasionally they will flash, or take a while to light up. If this is happening you should replace the tube asap because a tired tube is placing extra stress on the transformer. Tube lights work at a much higher voltage than 12v, so each light has a transformer in it - usually a small box at the end of the light. It is the transformer circuit that is important, because if that goes faulty, then you have a problem, because they are not readily available. In extreme cases they can get hot and give off foul smelling acrid smoke - this is the smell of the chemicals used in the capacitors in the circuit. Once this happens, you need a whole new tube light.

As far as I am aware, the tube lights used in classics are no longer available. I am not sure who manufactured them, but it is not just a matter of phoning a dealer and ordering a new one. Your only options are to either replace the whole thing with a different, more modern one, or, if you fancy a bit of DIY, you can convert the old lamp to LED. LEDs work off 12v so don't need a transformer. There is usually a white or silver reflector running the whole length of the fitting, and this is ideal for sticking one or two strips of self adhesive LEDs. You then take the 12v wires that were originally going to the transformer, and connect that to the LEDs. Done properly, the whole fitting appears unchanged, and if you use "warm white" leds as opposed to "cool white", the final result will be satisfactory compared with the original. This is an easy job for kitchen lights that have an external switch, but less so for the lights that have the switch built into the unit, as this is usually part of the transformer unit. However it can be done if you are happy to use a soldering iron.

Another option is to embark on a quest to find an original second hand - they were used on many vans and caravans, not just Hymers, so there will be one sitting on the shelf of a breaker somewhere. You don't even need the correct size, as the transformer units are pretty standard, and if you are even slightly handy at DIY you can cannibalise a transformer and transplant it into yours.

So with all that kerfuffle, it is easy to understand why people may chuck in the towel and install a new lamp - but the thing to remember is this - it can be done!

Halogens. These are the small round spot lights found above the bed and in some dining areas. A halogen light is just like a normal filament bulb, but with a bit of halogen gas inside the bulb. This makes the filament burn more brightly, and gives off a lot more light for the same power - but also a lot of heat. For this reason people think they are very inefficient. Well they are when compared to an LED, but the halogen spots in classics are quite small, and in reality they don't use a huge amount of power. They give off a warm light, and again, the colour of this light is in keeping with the classic feel. If you like them, you can keep them. If you don't like them you can change them. There are several LED equivalents. Because you are only changing the bulb there is no major surgery and you can revert back to halogens easily, or experiement with different types of LEDs.

Incandescents. These are the normal 12v bulbs and usually found up front around the drop down bed. Also in the cab lights. These are pretty utilitarian in nature, and don't need much discussion. They are not usually left on for long periods of time, so power consumption is less of an issue. There are LED equivalents of all these 12v bulbs, so you can experiement to your hearts content.

However the one exception is the bathroom light! Most CH bathrooms have the "classic" vertical lighting column, behind a vertical plastic shade (which benefits from a good wash occasionally!) adjacent to the mirror, and contains 4 x 23w classic 12v tail light bulbs. Total consumption almost 100watts! This is the light that causes the most consternation for owners because of all the lights in the van, this is the one that causes the "STROM" meter to deflect most noticeably into the red. It is the grandaddy, and the other lights dim in courtesy! But it is also sexy, and very fit for purpose, and typically Hymer. Men hardly notice it - as long as they can find the roll they are happy, but for the ladies and teenage girls it's the most important light in the van. It's the makeup light. So mess with it at your peril! The 4 bulbs and the colour of the shade give off just the right light for doing makeup and girly things. It is also very useful for a decent shower if your van has one. There is nothing worse than showering in the gloom.

Those 4 x 23w lights consume just under 8 amps. A fully charged normal leisure battery will keep the bathroom light shining brightly for about 6 hours. Non stop. The average bathroom visit is 2 minutes for a man and 15 minutes for a woman, unless it's Saturday night, in which case add another hour. But do the maths - even using the monster light in the bathroom for an hour, it will only use about 10% of the battery. And this only applies if you are wild camping - ie not hooked up. When you are hooked up, power consumption is insignificant. Even if you are wildcamping regularly, your battery should do you for 2 days, longer if you have solar, and every hour you drive will charge your battery up 30 to 40%. The worst thing that can happen is that you leave the bathroom light on all night - that will usually flatten your battery - but it's a rare occurrence and easily solved by starting the engine.

Hymer knew the bathroom light would use a lot of power, but they also had decades of experience and the sense to know that some things just can't be compromised, and that of all places, the bathroom needs good light, as with the kitchen to a lesser extent.

So think twice before just buying any old LED bulb for the bathroom, and don't just change it for the sake of it. If you put in bright "cool white" bulbs you will end up with a bathroom that looks like a scene from a horror film morgue. Cool White is a no no and Warm White is the way to go, and experiment - or just leave alone. You can also install LED strips - see photo below of my installation, which is the third version in as many years before I finally got it to our satisfaction. It also helps to fully involve the female members of the team when choosing bathroom lighting.

So that's the lowdown on lights. Other than the technical issues of maintaining the original lights, the main point I am trying to make is to think twice and plan carefully any LED upgrades, and get familiar with the concept of "colour temperature". The wrong colour light can be really annoying. The other point is that that the original lighting was good for 30 years before LEDs came along. Batteries are meant to be used and are more than capable of keeping the lights on for normal use. You only need to consider modification if you really intend to go off grid for long periods of time - ie more than 2 days at a time.

Standard Hymer tube light. The transformer circuits and switch are the white bit at the left hand end. Remove the shade with the thumbscrews.

Standard halogen spot. Easy to replace with an LED bulb. But do you really want to?!

Original kitchen strip light. This one had it's transformer and switch up in the panel. When it blew a year or so ago, I replaced the tubes with LED strips.

Illuminated!

LED strips with door switches are a cool modification. No more peering in the back looking for the Branston. Fiddly to wire, but well worth it.

Before

Same for the overhead cupboards. LED strips fit nicely under the front top lip, and take their power from the wires feeding the normal lights. The overheads are a lot easier to do than the vertical kitchen cupboard.

Before

I replaced the 4 bulbs in the central column with warm white LED strips, and extended the strips over the mirrors. I have a separate shower cubicle to the right, and the idea was to throw more light into the shower. This is a low exposure photo that doesn't show how bright it is, but shows where the LED strips are fitted.

Modern Insurance

25 years ago there was an insurance broker on every high street. You got to know him after a few years, and he usually handled everything. If you had a claim, and you had a good relationship, then no problem. If you had to cancel because you sold a car, then he'd refund you pro rata. Then the internet came along and a huge relaxation of what and what could not be advertised on TV. Direct Line started it all, even befoe the internet - cut out the middle man. What we see today is an orgy of direct selling in a highly competitive market. Baby Boomers remember the old times and shake their heads in dis-belief, yearning for the old days. Do you really want to buy a financial service from from a bald headed bloke in half a suit, hotpants and a wiggly fat arse? Or are you going to be impressed by some bloke with a big moustache? No, me neither, but what's the alternative? The trouble is, our sons and daughters, the millennials, have fallen for it hook line and sinker, because they grew up with it. We try and warn them, and get called fuddy duddy. Of a £300 premium, the underwriter probably gets just over half. The rest goes on a raft of middlemen - TV companies, creatives and web entrepreneurs to name but three. And it's ultra competitive. The only way the new style brokers can make any money is by squeezing margin out of every aspect the process. So you get recorded announcements about terms and conditions, and web pages that won't allow you to progress unless you click "accept". They have people who's job description is entirely predicated on creating loopholes that generate margin. The oldest trick in the book is the numbers they make you call from which they get a kickback per minute from the phone company. I used to work in that industry. Callshare paid for my first Hymer. Only in the last couple of years have the regulators finally started to do something about the scandal of premium numbers. For years they had a cosy cartel because 0845 numbers were charged at full whack from mobiles. It's not just insurance, it's almost every aspect of modern life. Mobile phone roaming abroad is another one. But the corporates are such a strong lobby and they fight every aspect of regulation - so government becomes bloated and corrupt trying to sort it all out. They are now legally obligated to provide 03 numbers - but you try and find them on their webpages. And Brexiters take note - you can thank the EU for a lot of effort in trying to get a better deal for us all in this and many other respects. It wasn't perfect, but they did some great work. And If you try and take them on, they tie you up in procedures designed to make you get bored and just give up. They threaten your credit rating, which can be a big thing for many of us. If you have the time, and treat it like a game, you can actually take them on and win. They actually cost in a percentage for complainers that go the whole distance. The trick is to get your case allocated to that percentage. If you turn up at County Court fully documented up, you will win 9 times out of 10, because they won't actually send a lawyer - it's too expensive. Same with the Ombudsman, as long as you have six months or more to spare.

So what to do? You vote with your feet. Three years ago I went back to a high street broker - they still exist. He - it's a she actually - gets all my business, and it's not actually that much more expensive. In fact we are lucky when it comes to insurance, because we actually still have a choice. Bank managers have all but disappeared unless you are a big account. And just look at the mess with energy prices. So you just don't use them. OK sometimes you don't have much choice, so you just do what you can with your eyes wide open, but with insurance you most certainly have a choice. You find a broker, make an appointment, sit in front of him and watch his eyes, ask all the right questions, and make a judgement call. If happy then you give him all your insurance. Don't begrudge him his cut, but make him work for it. If you cost your own time at £25 an hour, which is dirt cheap, then it's worth paying 10% extra, in fact it's a bargain.

Headlights

RONS TECHNICAL TIPS NO. 555 LUMENS. MERCEDES HEADLIGHTS.

EDIT 2023 - NON WORKING HEADLIGHT ADJUSTERS ARE NOT A UK MOT FAIL AS LONG AS THE HEADLIGHTS ARE A NORMAL HEIGHT. MOTORHOMES ARE EXEMPT FROM THE REQUIREMENT TO HAVE A WORKING ADJUSTMENT SYSTEM.

I've been meaning to get to grips with my headlights for a while. Not only are they pretty dim to begin with, after 20+ years they get even dimmer. I have seen several posts on here over the years about it. Bulb failures are quite rare, but if they happen, and you need to change a bulb, from the experiences of others it seems to be quite a job because you are working in a restricted space behind the front body work through the bonnet.

In principle, the job is easy - you twist off the cover, push and twist the holder, and it all pops out. The reality is quite different. The flipping things are stiff with age and because you are working blind you are scared of breaking them. What I discovered today should hopefully make the job a lot easier.

Basically, on a Merc Hymer, it's easier to tackle the job from the front! In the time it takes to mess about from the back, you can have the front grille off, 4 bolts, and another 2 screws to remove the indicator and surrounding trim, and then the whole headlight is exposed. On some vans I have been told that the surrounding trim has additional screws in teh aluminium side trim - look for these if your trim does not come away easily. Then 4 screws at each headlight corner and the whole light comes out. The glass lens comes off very easily with just one screw at each corner. There is a rubber seal between the glass and the body. You only need to take the glass front off if you intend to clean the silver reflector and the inside of the glass. If you only want to change the bulb, then leave the glass on.

Once you can get at the thing with both hands, the plastic dome cover comes off with a twist, and so does the bulb holder. Changing bulbs is then a doddle. I recently bought a set of higher power bulbs and a set of LED side light bulbs at the Hymerfest, and fitting them this way is easy.

I also had chance to examine and work out the headlight adjustment mechanisms. A lot of Merc vans have a headlamp height adjustment that is operated from a big knob on the dash, or a knob mounted under the drivers seat. The system is hydraulic - tubes full of water go from the knob to the back of the headlight. The system doesn't age well, and although I know a few owners who have a working system, the majority of us don't. Either pipes get damaged or they lose pressure, but basically they don't work anymore. Headlight height adjustment is less of an issue for motorhomes, as we generally have a constant ride height, so we just put up with it at a fixed height.

The hydraulic system is just about impossible to repair. If you are dead keen on height adjustable headlights then there is a firm in Germany who make a conversion kit to electrical adjustment. I have the link if anybody wants it.

So you have the wires going to the headlight for the 12v power, and a small plastic tube going to one corner of the back of the light. I just snipped it off. I then unplugged the wires to the bulb, and then had the whole unit in my hand.

The mechanism is quite simple once you get a good look at it. In one corner is a ball joint, in another corner is the adjustment arm from the hydrraulic tube, and in the other corner is the manual screw adjuster that you can see at the back of the headlight. The good news is that there is a manual adjuster screw collar on the hydraulic side, so having snipped off the tube, you can actually adjust the headlight to your desired setting. It's hard to put into words, but once you have it front of you it is easy to work out. 

However if you are happy with your general headlight adjustment and only want to change a bulb, or clean a lens, then doing it from the front is the way to go. 

The new 100w bulbs are really bright, but not ridiculously so compared with all these new technology bulbs on modern cars that are constantly blinding you, and the little blue LED sidelights are funky.

The whole headlight assembly is really easy to get at from the front. I cleaned and serviced and lubricated and polished the whole lot in about 90 minutes start to finish. Now better than new.