MY94 XJ12 Rust hole behind the passenger side front fender liner

So last night I decided to jack up the car and look at some loose wires hanging under my white 1994 XJ12. While I was under there I thought I would also do some investigation about a wind noise I had been hearing from the passenger’s side front footwell when driving down the road. I pulled the front right wheel off the car and started digging about. Just below the bottom of the inner fender liner I found this:

Once I found that hole that was only about an inch across horizontally and about 2 - 3 inches vertically I didn’t think this was enough to cause all of the wind noise I had been hearing so next I removed the various fasteners holding the back half of the inner fender liner so I could pull that away to look behind it. As I suspected there was a larger hole behind the lower corner of that fender liner.

So I guess I have to remove that front fender so I can get at this and try to make some patch panels and use my mig welder to put them in. Hopefully without burning any wiring or other stuff that is exposed behind this hole.

Typical rust damage from water dripping on to wiring harness from windshield drainage channel. I posted a guide on how to remedy the problem, but of course in your case much repair will be needed before thinking about remedies.

here’s the thread

I found the same problem on my old 94 Sovereign when searching for the source of constant wet carpets. It was a long time ago now so I’m not certain but I think one side has a large wiring loom that passes through a rubber sealing grommet in that spot, and the other side has a thin unpainted blanking plug that disintegrates through rust and leaves that large open hole you have found. Both areas collect and hold mud and sludge. Removing the fenders is not too difficult but there are lots of hidden fasteners so it’s helpful if you have a manual. On my car all the bolts came out quite easily except for the headlamp fixings, it had the rectangle shaped lights and the nuts were so rusty I had to cut through them with a Dremmel tool.

Larry, Casso and others:
If my 1994 XJ6 with the weird ignition problem has the same issue with water getting down in this harness could that cause the car to either totally not start when it gets wet from rain or if it does start to just run really badly (lots of misses and hesitation in the ignition system)? I am now thinking I need to pull the fender or fenders off that car to try to see if this is a problem on that car too. I will first pull the inner fender liner out and see how much I can see there.

Is this wiring harness that passes through the bulkhead ahead of the door behind the rear section of the front fender only on the passenger’s side of the car?

I can’t really comment on whether it’s water entering at that point that’s causing your ignition problems. My car was running perfectly when I found the rust and holes despite the fact it had been festering away in that area for quite a while. It was the sopping wet carpets that made me investigate and not an engine or running issue, once the inner fender liners were removed it seemed obvious water was getting in at that point. I can’t remember if there is a wiring harness on both sides, it was over 15 years ago, but once the inner liners are removed it will be easy to verify, it’s a lot easier with the wheel removed, just shine a torch in and have a look. I wish you luck and hope you don’t find the horrors that I did.