Fixing rust pinholes in hood

~If the holes are small you might be better off treating the hood with a good phosphoric acid to kill any remaining rust, then spraying on a good epoxy primer like PPG DP-40, then just using a skim coating of body filler..

~You might be able to Mig weld those holes up but in a lot of cases if the holes were rust formed the welding process will pop & blow bigger holes in the hood.. Then it takes more heat & welding & before long the hood is warped & will need a lot of metal working..

~I guess it has to be determined while working on it.. Don't just set you mind in one direction & keep going until it's too late to stop. Try welding one little spot & if it works continue.. If it doesn't work the way you want, re-group & try something else..

~If you do try to weld it use a .020" or .025" wire & a brass backing.. Don't even attempt it with a .035" wire.. Keep the weld time very short & try not to warp the sheetmetal... Remember one good POP & you will wish you never tried to weld it...

JDClooney@aol.com

~I am also somewhat familiar with the Henrob torch & have even used one a few times.. I guess the Henrob would be good if that was all that was available but can't see that it gains anything over my Mig welder, Tig welder, Oxy/Acetylene torch, or Plasma cutter.. It does have a rather small hot flame if the correct torch is used so it would be much better than a Oxy/Acetylene torch for a small spot repair but wouldn't be nearly as good as a quick spot from a Mig. A quick hit from a Mig does very little collateral damage caused from heating of the surrounding area & if kept short causes little warpage of the area.. The problem he is going to have with any type of welding set-up if the rust that is in the metal pores around the rust hole.. Most any type of weld will cause the rust in the surrounding metal to pop & possibly make the area worse.

~Probably the best way to repair a rusted area is to cut the entire area out & install a metal patch in that area.. That would involve major metal work & possibly quite a bit of metal warpage.. If a large patch was installed then a stitch weld would help to keep the warpage to minimum...

JDClooney@aol.com

I have a Henrob torch, and it works pretty well, but I think you have to be a demonstrator at shows for at least 10 years before you get REALLY good. :) I can weld cast iron with mine that the local welding guy said impressed the heck out of him. I can gas weld thinner stock, but I do best down to like .040" stock.

The real problem seems to come when you work on the pinhole stuff is that the area around the hole is so darn thin, it's like welding a hole in foil.

The Henrob does a pretty nice job on the thin stuff, but where it excells is that it uses far less gas for a particular job. It really cuts thin stock well, as well.

Frank

I was thinking over this same problem a few weeks or a month ago, and talked to some of the local guys about it. One guy suggested something I might try next time. He was telling me of the new space-aged metal to metal adhesives put out by companies like 3M (Blksmok might be able to shed soome light on this), and that he had had good success just "gluing" a scrap patch to the backside for reinforcement, and has yet to have one come off. He said he made a couple of mistakes on a panel, and it was all he could do the get the durn thing off!. After the backside patch, he uses either a good quality filler, or something metal filled like "All-Metal", and then finishes it out as if it were solid.

I hate to think of something coming loose down the road, but it's really hard to tack-tack-tack with the Mig and not get some deformation like Clooney pointed out. My DuPont jobber has a sample display card with glue beads on it hanging in his wall, and there are about 20 different product samples displayed for attaching everything from trim pieces to door sub frames.

Maybe the bodymen on the board could jump in on this, but I'm thinking in low stress areas like sheet metal hoods and grills, it there's not too much vibration, it might be an easy way out of a potentially "sticky" (pun intended) situation.

Frank