'29 cowl & rust

[rer_239]

i've got a '29 cowl. whats the best way to derust it. does it have to be taken apart and do each panel separately or just media blast it while its together?

[SeaSlugs]

Not sure you know but the cowl pieces are spot welded to the lower firewall. I would remove every nut and bolt for sure.

I think the cowl pannels are pretty stout and already compound curved so i wouldnt worry too much about warpage from a media blaster (find something a bit gentler to be safe)

I would be mainly concerned about the inside where the wood sits in the subframe extensions and the small space between that triangular support on the inside and the outer cowl skin.Very prone to collect dust and turn into mud that rots the cowl panels out.

Id almost be interested in dipping it in something. Ill be watching closely as i will have to do this this summer.

[wrndln]

I have repaired several cowls on my 28 and 29 vehicles. Because of the gusset on the inside of the cowl, crud accumulates between the gusset and cowl panel causing the slightly thinner to rust through. The pictures below show how I repair the cowl panels. First I sandblast the cowl including the area between the gusset and the inside of the cowl panel. After cutting out the rusted area, using piece of copper as a backer to align the patch to weld the patch in place. Once the patch is welded in place, grind the welds smooth and use a little filler to make the patch and panel smooth. This method is much easier than trying to replace the whole panel, as only the triangular area is usually rusted through.
Rusty Nelson

[Chuck Dempsey]

SeaSlug says - "Not sure you know but the cowl pieces are spot welded to the lower firewall. I would remove every nut and bolt for sure." Any particular reason why? Thanks

[Synchro909]

I think I'd drill out the spot welds so everything is completely apart and can be cleaned properly and plug weld them back together afterwards. It should look like a spot weld and I'd use a penetrating sealer to ensure the gaps between the panels don't rust again around the welds. Concrete sealer is excellent for that - so is Penetrol.

[SeaSlugs]

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Originally Posted by Chuck Dempsey

SeaSlug says - "Not sure you know but the cowl pieces are spot welded to the lower firewall. I would remove every nut and bolt for sure." Any particular reason why? Thanks

Im not sure why - my guess to keep everythign nice and lined up at the factory on a jig. Then the bolts merely sandwich everythign together. Bolts allow too much wiggle i think and rivets may have been impractical/ impossible in some locations.

I think they are also spot welded along the bottom to the sub frame extensions. Not a super easy task to dissassemble without bending things.

[Chuck Dempsey]

Thanks, Slug.....