Hello to all, i just revived a 1979 Dodge Vogue motorcoach, and would like to share my problems and solutions with you.
Maybe this might be helpful to owners of newer motorcoaches as well.
Please be aware that i am not a professional, and on top of that human, so my solutions might be less than perfect or downright stupid.
List of things to do when you check a motorhome which is older than one year:
- interior sniff: is it smelly?
- interior looks: any visible stains/signs of humidity? (floor, walls, ceiling), especially corners, kitchen, bathroom - open all compartments, check under carpet
- outside: take out a couple of screws from exposed areas (windows awnings, roof corners, ...) and check for rust - if there is rust, take out more screws to pinpoint the source - expect serious water damage. Especially fishy are screws used to mount (after sale) accessories (roof ladder, bike carriers, handles, etc.)
- use a moisture measuring device: check the whole interior (floor, walls, ceiling), write the result on a post-it and stick it to the point where you measured. This should be done every 40 inch, covering the whole interior. If all results are the same (and low) - good. If the numbers are uneven and rise close to critical areas - keep measuring until you pinpoint the leak.
- If you identified a leak, open the area around it (inside and outside - especially below it), and check for water damage. Be aware that water can travel long distances undetected and might leak out far from the point it came in.
- donīt be shy to rip out all suspicious material - do it nice or do it twice is my rule for these things.
- It might be necessary to spray the leaky area from the outside with a water hose and use toilet paper to look for humidity - dont`stop until you are sure about the root cause of the leak.
- I definitely cannot access the suspicious location from the inside, because it is behind furniture, bath, ...?
Ok, before you go any further: this is a last resort if there is no other way, and can only be done if:
- your motorcoach has a sandwich type wall (e.g. GFK/Styrodur/GFK/wood)
- you made absolutely clear that behind the hole you are about to cut there are no power lines, plumbing (water, gas) and that you will not cut through any supporting structures (wooden or metall beams)
- you painted the cut lines nicely and rectangular, parallel to the vehicle structure and
- thought long and hard if the hole might be designed to be useful later (vent, trash box, luggage compartment, safe, ...). Check if there is a cover available and size the hole accordingly.
- take a jigsaw and carefully cut a nice rectangular hole in the wall, make sure not to damage the cut part, as you might need it to reclose the hole later.
- if your wall is sandwich the you can reclose the hole with the cut part and pu-foam (attention - only use the water proof type for well sealing) which you spray into the cut gap - the foam will expand and seal the whole cut (cover with tape to keep the foam from drippling onto the walls. I used aluminium ledges to cover the cuts from the outside, doesn`t look too bad (i hope)
- use a jigsaw blade, which is not longer than the wall thickness (blade fully extended) as not to cut structures behind the wall
This is usually the point to reconsider your decision to buy, sell or burn the motorcoach, be advised that if you cannot repair water damage yourself things will get very quickly very expensive - it might be better to look for alternatives.
There are two basic types of motorhomes:
Sandwich wall motorhomes and the ones with sheet metal walls with glass wool (or other) insulation in between.
the sandwich type (most older us motorhomes) uses a metal structure for stability, and can handle water damage far better than the sheet metal wall type (most european motorhomes) which usually uses wooden beams for stability.
a wet sandwich wall will usually rot on the inside wooden layer. The rotten wooden layer can be scratched off and repaired with no damage to the structural stability of the motorhome - if the metal supporting beams are not heavily rusted, which is rare, but possible.
If sheet metal wall type gets wet, the wooden beams are being kept wet and warm in the wet insulation and will start rotting fast - meaning total destruction in a couple of years.
The problem is that many sheet metal wall motorhomes with rotten beams look nice, but are being kept together by the sheet metal wall itself, which is not very stable. So the whole body moves a lot while driving and more and more cracks develop, more leaks, more beams rot and so on.
Why is that - are the manufacturers of sheet metal wall type motorhomes all criminals who build cheap?
I think there is more to that: first, when the sheet metal wall type was introduced in europe, motorhomes were smaller and lighter and could cope with the forces created while driving e.g. over bumbholes.
Then, as customers requested more space and comfort, they grew bigger and heavier, loaded with creature comforts like central heating, toilets + water and sewage tanks, tv, microwave, a rubber boat on the roof, bikes in the back and so on.
Only ten years ago, rooftop a/c`s were very rare in Europe. Now everybody wants them, and they represent a heavy load on the weakest part of the motorhome - the roof.
In the US of A, bigger was allways better and rooftop A/Cīs were common for 30 years, so there was never a real choice for maufacturers.
Ok let`s move on - you decided to go for it - next steps:
- leaky or not - start replacing/reasiling all exposed outside seals:
- take off all plastic or aluminium rails, corner covers, guards and so on that you can rip off the body and check for water.
- clean all seal surfaces with degreaser (remove all old sealant with thinner), put plenty of new sealant (no silicone, the acid is bad for aluminium) an e.g. the rail und screw it back on - the excess sealant should be squeezed out along all edges. (masking tape might be a good idea) - remove the excess sealant with a spattel (there are special rubber spattels for this job which create smooth round or straight edges)
Just scraping of the old sealant without removing the rail/cover/guard will not do the job!
On older RV`s i do recommend to take out all windows, vents and doors for resealing.
I currently use one4all as sealant, i do know that there are professional products on the market, but if you spend more than 20 cardridges (and you will) it makes a difference whether you spend 5 or 15 Euros per cardridge and the price should not keep you from using the stuff generously.
Thatīs all for now, please leave comments/corrections and tell me whether you like my input and let me know your own ideas on the subject.
If you like me to go on, electrics will be the next chapter.