Odd 964 Rear Seat Retention Bolt Rusting?

[A 911 Dream]

Good evening Pelican Braintrust,

I am considering purchasing a 1990 C4 and the rear seat retention bolts are severely rusted.

I would welcome comments, reasons and if this is a common issue?

I don't think I've read a thread on this before?

[john walker's workshop]

Unscrew them, clean and paint?

[Ctopher]

Actually that’s interesting as I have similar rust on my 87 Carrera coupe rear seats. I have not removed and/or investigated further. Would water from rear window leaking cause this? What about water on the rear shelf? Something to think about and maybe investigate. I need to do the same.

CTopher

[GeorgeK]

These bolts for some reason seem to rust very easily.
That said, it is from moisture, i.e. water ingress. Look for other signs, esp. in the seat pans.

[Flojo]

poor coating back in the days, humidity in air, the years passed… rusty.

retrieve, blast, coat, done, get out and drive :-)

[Ian Comerford]

Agree with Flojo. If that’s the worst rust on the car, be very happy!

[ClickClickBoom]

Beware!
Water in that area could be from a leaking window seal. Look very closely at the seat pans. Zinc/Cad plating is sacrificial. When it is gone, the steel will begin to corrode(rust). My question is what else is rusting?

[dg567]

Those bolts are also likely seized. They're very hard to remove in my experience even without showing rust.

[jac1976]

Originally Posted by Ctopher

Actually that’s interesting as I have similar rust on my 87 Carrera coupe rear seats. I have not removed and/or investigated further. Would water from rear window leaking cause this? What about water on the rear shelf? Something to think about and maybe investigate. I need to do the same.

CTopher

I’d pull your carpet and further investigate. Most of us rarely use or acknowledge the rear seats so a leak can go unnoticed for some time.

Since the OP is looking to purchase he may not be able to pull back the carpet on the subject car. It is hard to tell from the photos, but it looks like there is glue visible at the edges of some of the carpet pieces which may indicate repeated wet and dry cycles. This could be due to regular wear and tear, but again these areas typically see very little traffic.

[Snitzler]

If you can, pull the carpets and look for moisture. I was lucky, I removed everything in the back to prepare for an RS carpet kit. The carpet was wet and the rear seat pads were wet and "mushy" Both seat pans must have stayed wet enough to go through the coating with one side rusting through. I wonder if I bought the car with wet carpets and it just never dried out? Car did smell a little funky but I thought that was Porsche smell!

[RedCoupe]

My 1990 C2 had water ingress into the rear seat area a few years back. I thought it was coming from the rear window seal, but it turned out to be plugged sun roof drains.

[bkreigsr]

Originally Posted by dg567

Those bolts are also likely seized. They're very hard to remove in my experience even without showing rust.

I use a big Craftsman screwdriver (16.5" total length) and a 3/8ths open-end wrench on the shaft. Couple of over night soaks also helps.
If you screw this up, the alternative is a to drill out the screw. - very messy.
Bill K

[Bill Douglas]

If you want to reuse the bolts a quick and nasty way to refinish them is to clean them up with a wire brush etc. Then heat them up with a gas torch and dip them in any old oil. It makes them a LOT more rust resistant and a cool black colour.

[kuba_kuba]

My '88 had the same thing. Dry car, no rust, no leaks (well it's a targa so there are leaks but not in that area). A big screwdriver, patience and overnight soaks will get them out.

[jac1976]

Originally Posted by kuba_kuba

My '88 had the same thing. Dry car, no rust, no leaks (well it's a targa so there are leaks but not in that area). A big screwdriver, patience and overnight soaks will get them out.

This may very well be the case, but I’d check anyway.