Elevating roof

[Juicy]

Check for corrosion between the elevating roof and the black rubber seal that seats the roof against the body of the vehicle. The seal is rubber but has a steel spine that grips it to the aluminium roof. Water gets trapped within the seal and an electrolytic action takes place between the aluminium and the steel. This results in blistering of the paint where the roof joins the seal. Beneath the paint the aluminium corrodes and turns to powder. My California was 6 years old when I discovered the problem. I took the vehicle to LCW centre at Cleckheaton and they received an authority from VW at Milton Keynes to reprint. I wasn't convinced that this would remedy the problem and they were to sub contract the work. I then went to JCT 600 at York who have their own body shop. I showed them the problem and there was a slight perforation of the roof on the rear near side corner, where moisture sits for longer. York contacted VW and after some denial they agreed to replace the roof (£2500).
I took the opportunity to replace the bellows at the same time at my expense (£425). Vw also eventually agreed to replace the seal at no cost.
A tip is that the roof, bellows and seal are available as a complete part, a bit more money but it takes the human error out of fitting the bellows and seal. It is worth insisting that this is ordered in order to avoid the shoddy workmanship that is prevalent at most VW van centres.
I have sealed the roof to the rubber seal in order to prevent water ingress.
VW asked me not to broadcast this warranty claim as they don't want others owners to do the same!
CHECK YOUR ROOF BEFORE YOUR 12 YEAR WARRANTY RUNS OUT AND DON'T TAKE NO FOR AN ANSWER.
Another tip is that The dealership has only one attempt to make a corrosion repair, if not successful the onus is for any further remedial work to be at the expense of the repairer.