All: Did the factory, or have any of you when re-assembling your F100 or F250, use caulking(dum-dum) between the inner fenders and the firewall or rad support, or between the inner fenders and the outer fenders?
Thx. Jeff

 

When I was playing with my Merc 20 years ago I wanted to prevent future rust in this area. I was a poor *** kid so I took some plastic milk jugs and made gaskets out of them. The ones between the inner fender and the firewall fit like a hot damn and because they were clear you could not see them.

 

I'm pretty sure this old rusty F250 parts truck is still wearing all of it's original parts. There is some sort of tar type sealant at the firewall. That could have been added at some time, but it is between the firewall and inner fender. The inner and outer had a double bead of some sort of butyl calk between them. It has turned as hard as Chinese arithmetic and is falling out.

 

Yes, a thick blob of the black stuff at the firewall and a smaller bead (1/8" ?) between all the other pieces.

 

I agree and noted it upon disassembly as well. I will use strip caulk anywhere metal touches metal as well as to seal holes in the firewall or floorboards. Use 3M strip caulk #08578. One box will last you a long time and it has other uses as well...very sticky...easy to work with.

 

personally I like the gasket method, I've never tried the milk jug method, but I have used regular tar paper. Although they call it felt paper now, not sure it has any tar in it anymore.