For reasons that are not very clear the 1991-on XJS coupé and convertible suffer from hidden rot at the base of the windscreen. The earlier coupés had a rubber-sealed screen and these seldom suffer in this way, though it is not unknown. This problem gets even worse with full facelift cars (1993-on) which nearly all have the problem.
The first sign of trouble is a small, innocuous-looking bubble appearing at the forward edge of the bright finisher. But this is the tip of a spreading area of corrosion carrying on invisibly in the screen rebate and under the finisher. Very commonly there is actually a hole under the finisher and water will be dripping onto the floor in heavy rain.
We have a theory that during the original factory installation of the screen a sharp tool or jig is used the centralise the screen. This tool appears to scratch the pain in the same area with the resultant water ingress and rusting following close behind.
Repairs in this area are difficult, and repair panels are no longer available, necessitating some skilled steel cutting and welding to replace sections of the surround. In very bad cases the entire lower scuttle must be cut out and a rust-free panel cut out of a donor car and grafted in. Expect costs from £525 to £2100. See a gallery of horrors here.
It is also very common for rust to bubble up at the top of the screen at the rear edge of the finisher. While this is easier to repair technically, it can be costly because to achieve the best paint match the whole of the roof needs to be painted – which means carrying the paint down the buttresses. Even these don’t have a clear demarcation from the rear wing so one can end up painting both rear wings as well – which in turn means blending in to the doors!
There’s nothing the owner can do to prevent this problem developing – even keeping the car scrupulously dry will not stop pre-existing rust from previous ownerships getting worse; and screen-wash can be a problem too. However, it is important to get the problem resolved as early as possible to reduce costs, so keep a very close look-out for rust in this area. See below:
KWE has repaired many of these cases so do not despair!
* The car’s ‘scuttle’ is that flat area of metal between the bottom of the windscreen and the bonnet.3:10 pm