Damp in my Hymer Camp 48

[Sam P]

Hi All

I've been reading some of the info on these forums and I'm hoping some of you might be able to advise? I have a LHD 1995 Hymer Camp 48 which is based on a Ford Transit, It might be a bit of an oddity as it has some markings that seem to indicate it was built in France? But it is definitely a Hymer.

Towards the end of Autumn last year I noticed some tiny holes appearing in the aluminium panel at the back of the van along either side of one of the alloy rails. After looking into it online it seemed that damp must be getting in through the alloy rails and any timber inside was wet and causing the aluminium to corrode. I covered the van up for winter and in the meantime bought new edge seals and screw covers to replace the old and new mastic tape to seal under the alloy rails and a damp meter.

I have just started resealing the alloy rails now it's warming up and the rail that is nearest to the small holes seemed fairly well sealed but I cleaned it all up and resealed it. However, I decided to do the rail below and above to be on the safe side but when I removed the lower rail it was easy to pull off the van without unscrewing anything!! Whatever the screws were attached to appears to have rotted away under the alluminium(although the aluminium in this area looks ok). I think there must be a long term problem somewhere at the back of the van and have decided to remove the interior walls and cupboards so that I can get at the rotten areas and replace them and patch up the small holes in the aluminium.

I have been looking for advice about removing the rear kitchen and bathroom to be able to get at the problem and it appears that Hymer motorhomes after 1978 were made with the PUAL construction technique which apparently has no timber in it? Can anyone tell me what the alloy rails are screwed onto if there's no timber in the frame and also if it will be possible for me to replace the rotten area if it is all sealed together? Will I have to rip out the inner wall and the polyurethane insulation to get to the aluminium from the inside? I'm hoping I can salvage the inner boards as they appear to be dry? I don't think I can just reseal it and can't really because there isn't anything sound to screw the rail to. I'd really value any advice anyone can give before I go any further with this whether it's how to remove walls without damaging them, what I might find once I remove the inner wall in terms of how it's constructed. Just any tips and advice that might help this go smoother and please don't suggest we sell it because we love the van and want to keep it even though it's giving me a headache thinking about what we need to do! Thanks for reading and hope you can help.

[StuartO]

Some Hymers were (and maybe still are) built in France.  Not all Hymers are built the same way and a coachbuilt of this type may be more prone to water ingress than the A Class types.

 

Don't assume that a DIY repair is the most cost effective approach because as you are discovering, you can ned up flying blind to expose the underlying problem.  If your damp meter shows no dampness inside you may only need to refinish the outside.

 

Where abouts in the Country are you?  Any caravan reparer should be able to help and asking for advice and a quote could give you valuables clues about how to proceed.  You may be surprised that a professional repair need not be expensive.

 

[Sam P]

So.... just thought I'd update everyone as I'm sure one day someone might need some of this information. I decided to investigate why the aluminium panel would be getting holes in it and thought I'd remove the bathroom suite to get to the wall at the back of the motorhome and just check that it was dry. Removing the bathroom was fairly straight forward but I had to go very carefully with the 22 year old plastic shelves etc as the plastic is very weak/perished, also I had to remove the 2 mirrors which was really tricky as they were glued on with double sided extremely strong tape, I recommend using a picture wire to cut through the tape, run it down both sides of the mirror and cut the tape, a bit like cheese cutting. I think that was the most difficult part of removing the bathroom but I had to remove the mirror to be able to get at the bathroom cabinet. Anyway I finally removed the bathroom wallboard to reveal the actual rear panel of the van. The Hymer is indeed constructed with the PUAL system which is basically wallboard glued to polyurethane foam glued to the outer aluminium with a steel frame placed between the aluminium and wallboard with the foam sitting in with the steel, there is no timber involved. Sadly I found this out because the back wall of the motorhome was very damp from the floor upwards for about 60cm and the wallboard was so damp it had come away from the polyurethane foam. I removed the wallboard and the polyurethane foam being waterproof was intact but had water sitting in it so much so if I pressed it water squeezed out! The steel frame underneath is very rusty and has holes in it. This has obviously been leaking for a longtime but was totally unnoticeable when the bathroom was in situ. I only became aware of it because of the small holes appearing in the aluminium outer panel, these holes have appeared exactly where the steel frame sits so the aluminium must be reacting to contact with the water and rusty steel? I am still unsure where the leak came from as some of the board that I removed to get to the steel was actually dry but the steel underneath was seriously rusted. I have some thoughts on this, 1. the alloy rail approx 80cm up from the floor was leaking and the wet got in and sat on the foam until it finally penetrated through to the steel or 2. I also found that the rear number plate lights and brake lights etc had been really poorly fitted and masticed into large holes rather than sitting on top of the aluminium so I imagine these have been seriously leaking and the moisture having nowhere to go may have risen upwards? or 3. a combination of both. Does anybody have an opinion on which might be the culprit? This has turned into a massive job but I am determined to sort it out now I've gone this far and hope to save the motorhome we love. I have removed all the foam around the steel and am going to have to take the rear aluminium panel off to expose the steel frame and then I'm going to get a welder to replace the steel that is rusted and once that is done I'll replace the aluminium sheet, glue in new foam and glue in a new wall board and then replace everything resealing any possible leaks as I go. I would say as I took the motorhome apart I was impressed with the build quality but the fitting of the rear lights was attrocious and I wonder if that is something that is put on later as it doesn't seem to match the same Hymer quality. I would recommend anyone with this model of motorhome to just check how their rear lights are attached. I hope I'm approaching this the right way, I'm not in a position to spend hundreds getting it professionally repaired but I'm willing to put in the hours to get the motorhome back to top condition. If anyone has any tips or advice as I move onto the next phase of this repair I'd be grateful. We are based in the Leicester area. Thanks for reading.

[lennyhb]

If your van was built in France it would have been at the Eriba factory in the Alsace area, this was closed a few years ago and all manufacturing transferred to Germany.

As you found out they used to use steel reinforcing they later changed to aluminum and with improved construction method neither is now used.

 

The pin holes are probably due to the van spending part of it's life in a salty atmosphere, we live 200 yds from the sea and had a caravan that had that problem and as you found out the only real cure is replacing the panel.

I suspect most of the water has come in via the rail but without photos hard to say, I do wonder if it has had a rear end shunt that has not been repaired correctly probably with inferior sealants used on the rail and replacement lights fitted badly.

 

Good luck with your repair it sounds like you are doing a good job.