how does rust get in between wheel arch
I got one rust hole on my xjr-100 right side
rear wheel arch.

 

Stone chips are first guilty subjects. And as there are a few metal panels in that area which are folded and welded it is normal... If Jaguar had installed plastic wheelwell trims the problems wouldn't happen. When the rust has gone, coating it with loads of paint helps. And then some good stone chip protectant...

 

there is a void between the 1/4 panel[rear fender]and the inner fender well where their welded together,the weather gets in and rots the metal.after repair is made use caulking too fill this void from one end of wheelwell to the other,work it in with your fingers.do not use straight silicon.steve

 

This was common in the early cars including the early 1995 x300's -- it was the main reason I traded mine.

Jaguar changed the manufacturing process in 1996 -- I'm surprised you had this problem. I have not seen any newer ones rusted in that area.

It was such a problem in the early cars that you could purchase a patch panel to weld into the arch -- they did not make one for the later cars.

Unless it is all cut out and patched properly -- it will come back. Cleaning and bondo will only get you a year or two

 

ill supply a pic soon

 

can I access the rust from behind if I take the bumper off and as a side note my rear back up sensors are not working I was wanting to check the connections if I take the rear bumper off can I access these too.
thank you for the help
james

 

The typical rust spot was at the top of the rear arch.

That could have been caused but a small hit to the bumper -- causing the paint to crack.

 

Every XJR/100 I have seen has had this problem.

Very sad when the cars are otherwise pristine.

 

I agree with Plums, mine looked exactly the same. Take an angle grinder to that spot for more than 10 seconds and you'll have at least a 1/2'' hole. From what I remember you can only work from the outside>in. You would have to cut through from the trunk or the wheel well metal other wise, to me that seems like unnecessary work. Cutting/grinding out all the rust/rot and replacing with new metal is the only correct way. You could try to fill with filler then touch up the paint but it will bubble up under even normal conditions.
Here is a before pic from the driver side, the passenger side was worse