I’ve just got back home from university and started tooling on my car again and taken the time to explore the a pillar drains to address some of the small leakage problems and I’ve found that on both sides the black mastic putty substance has dry rotted away.

This in turn allows water past parts of the trim and allows the water to seep onto the door seal instead of down the drains. What do I replace this mastic with, or can I find more of it to mold into place?

Edit: pic attached of aforementioned substance

 

cstrad_8,

Do you mean the mastic which is part of the windscreen bonding?

If so, I'd suggest that you really need to completely remove the screen; try and salvage the mastic dam if you can as these are not available.

Sadly, you may well find corrosion in the windscreen flange caused by the shrinking of the mastic and the water leaks that have ensued.

Good luck

Paul

 

Your profile shows you have a 1986 XJS. If so, you have a rubber gasket holding in the windshield. It isn't bonded to the body like the facelift models. It uses some sealant in the grooves to help seal the glass to the rubber and the rubber to the body. You'd need to get a new rubber seal, and have your windshield removed and replaced. I believe there are some youtube videos on the process.
Jon

 

I think we’re a little lost in translation, the A pillar trim piece has some weird black sticky type seal on it over the seam of the body at the A pillar, that stuff is what’s rotted away, not the windshield seal itself, although both could stand being replaced.

 

Hi Paul,

in my original post it seems I was a bit unclear as to what the issue is. On the trim piece for the A pillars there is some sort of gasket that was attached to the trim piece as a means of directing water down the seam of the a pillar and out the front drains, this is the piece that I am looking to replace or remove, depending on what people advise is best.

 

A picture would help. Please attach one of the area you mean.
Do you mean between the bright trim and the windshield? If so, that's part of the rubber gasket.
Or do you mean between the channel that holds the door seal, the A pillar, and bright trim?

 

the second part is what I’m talking about, where the body panels are crimped together, it’s covered by this gasket material better seen in this photo

mine pulled off with the trim piece so I’m wondering how/what to replace it with since it is in such poor condition. Without it in there the water just falls into the door seal which is not any better than the current situation.

 

That is just mastic used to help the stainless steel trim stray in place and also to try to prevent the water draining down behind it from rotting out the A pillar.
As you have it removed, check the windscreen rubber carefully, as if it has solidified/perished, now would be a good time to replace it. If it is OK, then leave it.
The entire "drain inside the A pillar" is one of Jaguar's more daft ideas. I strongly suggest you block the hole each side of the car at the top of the A pillar inside the roof gutter with mastic. I did this decades ago and it has no ill effects and helps preserve the pillar and the scuttle from rusting out.

 

Thanks a million Greg, helpful as always. I plan on taking apart the car as much as possible in a few weeks here in a tall order to repaint it as it is, but I’ll add seals onto that to-do list for the future.

 

What is that mastic stuff made of? Is it like a plumbers putty that never cures? Or is it an actual sealant?

 

It almost feels like a sort of putty, the parts that have dried out are the ones that are failing so I assume it’s natural state is to be in a tacky way. So plumbers putty is likely pretty close to the original gunk they stuck on there.

 

Could you do Gorilla brand double sided tape instead? It's just to hold the trim on right? The water seal is separate?

 

3M makes a product called strip caulk, similar to what the factory used.

 

Yes, seam sealer, excellent stuff, comes in a tin to be brushed on too.

 

You are a life saver my friend, maybe now the water will be directed the right way instead of into my door.