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I have a set of NOS exhausts that were put on the car and only run about 25 miles and removed and stored for 25 years. The mufflers look brand new but the pipes have a coat of rust on them. Still has the original GM paper part numbers on them. Is there anyway to remove the rust and protect them or am I looking at new exhaust pipes? Hate to replace a perfectly good system.
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Re: EXHAUST PIPE RESTORATION
Robert-----
There's no reason to discard the exhaust pipes, at all. First of all, most of the NOS GM pipes and mufflers are discontinued so you can't just go out and purchase another pair. Even if you were to find another NOS set somewhere, the chances are they would be rusty, too. Yours might be a little worse off since they were installed, which got the rust problem started and accelerated. The real problem is that the original GM pipes were just mild steel and they rust quickly. The mufflers often had aluminized outer shells and some even had a stainless steel end-plate. This is why your mufflers are rust-free. However, the inside of them might be another story, but I expect that they are in very good shape.
You can clean the external rust off with a drill with a wire wheel attachment. It's a little laborious, but you'll be able to get most of the rust off and have the pipes looking clean again. Unfortunately, after you re-install the exhaust system, the pipes will just start rusting again and almost immediately.
You can also clean the pipes more easily with a chemical solution like Jasco Metal Etch (fast) or Naval Jelly (slow). Either way, though, the rust will return even quicker than if you use the wire wheel method.
It is difficult or impossible to protect original type carbon steel pipes if you drive the car. If you were to coat them with some sort of high temp coating or paint, they would not look original, at all. I've found hi-temp clears to be short-lived.
I HATE rust so you'll never see me use carbon steel exhaust pipes EVER again, original or otherwise. Mufflers are a different story. They can be coated with a high temperature black (as many originals were, anyway) and their aluminized construction will inhibit rust. I've always found that the section of the exhaust on 63-74 Corvettes which is the most affected by rust are the rear exhaust pipes which run from the transmission crossmember to the mufflers. These always seem to get the worst of it. They get UGLY fast!In Appreciation of John Hinckley -
Re: EXHAUST PIPE RESTORATION
Since they were on a car they are no longer NOS. Since they had paper tags on them they would have been NORS. (new old replacement stock from ther GM parts system) Since they were on the car they are neither NOS nor NORS. They are probably NOs (Neat Old stuff). In the straight axle years these pipes were coated with grease for shelf life. At St. Louis they were installed without degreasing and loaded with blackout paint during the chassis blackout process. Noland Adams refers to this coating as, "a mystery preservative much like cosmolene" (really painted grease!)
I'd install a set of aluminized pipes from Allens unless you want to have the car judged. Judges look for high carbon steel pipes with rust!
Dale.Comment
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Re: EXHAUST PIPE RESTORATION
you can always send them to a redi strip . you will loose the part sticker but the pipe will look brand new without sanding marks .Comment
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Exhaust pipe paper tags *TL*
Dale et al,
In some years, 1968-1972 specifically, the original factory installed muffler/pipe assembly had a paper part number tag on it, as did the exhaust tip. Don't rule them out just because of the paper tag. One has to see the tag to tell if it is as the factory installed or a Service Parts Operation tag.
Bob Cook (the Texas Bob Cook) wrote a story about these exhaust markings which I published in The Corvette Restorer, complete with photographs, within the last year or so.
Terry
TerryComment
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Re: EXHAUST PIPE s/Originals
Robert, I wish I knew what year etc. exhaust is off of. I would photograph every detail of the system before cleaning, then try to get the paper part no. tags off with a razor blade to put in your scrapbook. If you have early 70s model, look for the part numbers stamped into the header pipes at the rear end, where they join the rear exhaust. Where are the tags stuck on to the muffler? Mine were on the front face of the mufflers. Bob ( Ps. If these are going to be used as "driver" set, you may want to think twice, as their value, if original, is quite high.)Comment
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I'm Always Indebited
to the Department Of Corrections. Thank you.
Dale.Comment
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