My '64 F-100 is finally getting a 223 to replace the in-need-of-a- rebuild original. During the two years that it has sat idle, it has developed the beginnings of what it seems is probably a commom rusting problem. The crimped lip under the front of the hood has started to flake away from rust. I think I see how this common problem occurs (and maybe how to avoid it) and am inquiring as to anybody else's theories and about repair of the rust damage.

1) My truck has sat on a slight incline to the rear while it was idle. It appears that maybe rainwater that rolls down the front of the hood is able to cling under the lip and, if inclined even slightly, can get to the rear edge of the crimped lip without dripping off. Once the water drips reach the joint edge where the hood sheet metal joins the reinforcing nose piece underneath, it gets drawn into the joint space where it does its rusting mischief.

Does this sound plausible? If so, maybe it can be prevented by sealing that joint edge with silcon or something.

2) Is a good sheet metal repair possible here?

Thanks

Jethro

 

You've just discovered one of this series trucks' weaknesses. As far as I can tell, after doing some experiments, the rounded shape of the hood creates a venturi or suction effect on the inside, much like an aircraft wing does.
Water gets blown by forward motion under the hood lip, then the suction pulls it up to the underside. It then collects in the cavity formed by the forward round edge, the lip, and the upturned portion of the lip.
Unfotunately, there is no way to for the water to escape. If the water is salty, from de-icing, corrosion is sure to be swift and thorough.

On my '66, it looks like it is spot welded to hold the folded-over sheets of sheet metal together, so drilling those out would invalidate the integrity of the assembly. I don't want that hood flying apart on the freeway!
I put a bead of silicone along the inside of the hood, where the folded pieces join - and in spots don't join - the underside of the hood.

I don't know if that helped, because it had already started showing signs of bubbling up, which meant it was already rusted through. I found me another hood, but I'll need to have it painted and have a few little dings bondo-ed over.

Hope this helps!

 

Thanks, banjopicker.

I think our theories are along the same track, here. But it seems as though the rust on my hood really progressed in the last two years when the truck didn't move. I don't recall much rust there when I first got the truck two years ago. But maybe it had started. And I guess your theory could hold as my truck is nosed westerly into the prevailing winds. So, water could be blown under the hood.

I was hoping that some of the metal can be replaced with some welds while maintaining the original integrity of the manufactured hood.

 

Jethro, I know nothing about wlding or sheet metal replacement, so I'm sorry, but I cannot help you there. I sure think somone else on this list can, though1

 

> prevented by sealing that joint edge with silcon or something.

For my truck I would seal it with solder (after surface prep), then seal that with undercoating on the whole under surface of the hood. I seal lots of things with red RTV, but, a metal seam on folded metal is not one of them. Factory seam sealer might be better, but, rust still develops under the sealer sometimes and then rusts away unseen.

 

If you can get to it, use POR-15 or a simular product to seal it. If you can seal off ALL the rust and keep the moisture from getting to it, it won't come back. Later,