When you see rust perforation like this, there are probably a lot more areas where the rust is just about to pop through.
Q. My current issue is rust blisters approximately 1/4 to 1/2 inch in size, popping out next to the rain gutters on my Chevy. I want to grind the rust out and fix it permanently. I am sure that I will have to remove the headliner and place sheetmetal under the areas where I will be welding to keep sparks off the upholstery. Since I have never welded before in this area, and have no experience fixing roof rust, I need your advice. Should I just place a copper strip under where the grind holes will be and fill the holes with MIG wire? Or should I make sheetmetal plugs and TIG weld them? Will I have to deal with any driprail sealer catching fire, or with warping?
Would it be better to find a rust-free donor roof and weld that in? From your experience do you think this rusting next to the gutters will continue? Would you suggest removing the seat before starting on the welded roof repairs?
Ken
Baltimore, MD
Via the Internet
A. Most of the time when you see rust bleeding through the paint, what you are seeing is just the “tip of the iceberg.” It’s pretty likely that there are many areas where the rust has not quite broken through the surface, but it probably will in a few more months or years.
Rust is like a time bomb, and if you don’t cut every bit of it away, it will continue to eat away the metal. It’s likely that the rust on your roof has started on the inside, and is slowly eating its way toward the outer surface.
The first step is to do as much investigation as you can to determine the extent of the damage. You can use a tool like an icepick, screwdriver, or punch to gently probe the metal above the driprail, and it’s pretty likely you will find many more spots where the metal is very thin, just about ready for the rust to break through under the paint.
I would certainly remove the headliner, not only to prevent fires when welding, but also to allow you to see the extent of the rusted areas from the inside. Removing the seat is optional (you can cover it with some fireproof material to protect it from sparks) but you will certainly have much better access for your investigation if the seat is removed.
Once you know the extent of the damage, you can decide on the best course of action. If there are only a few small holes, you can drill them out and weld small plugs into place. If there are areas that are peppered with rust, with spots of thin metal distributed over a large area, it’s probably better to weld in a larger patch panel, which completely encompasses the questionable area. If you find that the entire area near the driprail is compromised, it might be easier to find a sound roof to replace yours. It takes perhaps 3 feet of total welding to fasten a new roof into place, and if you compare that with welding in dozens of small patches, replacement may be the better option.
You can use either MIG or TIG welding for patches or roof replacement. If you remove as much of the seam sealer you can with a 3M Clean & Strip wheel, you shouldn’t have much problem. Warping will certainly be a problem, particularly with a lot of patches a few square inches in size. Much of this damage can be repaired with a hammer and dolly, in areas where you can get a dolly to the back side of the panel, and TIG welded joints are generally easier to straighten.
You can email your questions to Professor Hammer – covell@cruzio.com – or mail a letter to Covell Creative Metalworking, 106 Airport Blvd., Suite 105, Freedom CA 95019. You will receive a personal reply! Ron Covell has made many videos on metalworking, and they can now be STREAMED or DOWNLOADED from his website! Check these out at covell.biz, along with his ongoing series of workshops held across the nation, or call for a current schedule of workshops and a free catalog of DVDs. Phone (800) 747-4631, or (831) 768-0705. Also, check out Ron’s YouTube channel – www.youtube.com/user/covellron.
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