Exhaust Pipe Weld Became 'Unwelded'...?

[timfitz63]

Well, yet another minor mechanical issue with Aztec Gold #15. How a fifteen year-old vehicle with only 10k miles on it develops these kinds of maladies is beyond my understanding... I've got a '97 GMC Jimmy with ~120k miles on it that still has the original exhaust system...

Anyway, when I backed the car out of the garage yesterday, my uncle noticed that the driver's side muffler shifted (tilted) noticeably when I put the car into reverse. When I investigated why, it appeared to me that the flange weld on the segment of pipe running over the transaxle became 'unwelded' right at its forward flange (where it mates to the pipe running aft from the engine). It just looks like the pipe and its weld came completely separated (no cracks or breaks evident) from the flange, and the pipe/muffler assembly is then free to swing on its hanger. I probably should have snapped a photo of the spot I'm trying to describe, but as I was crawling underneath the car, it didn't occur to me to do so... :duh Funny thing is, I didn't hear any increase in engine noise, at least not at idle (I didn't actually take the car out on the road); apparently the pipe stays sealed well enough to keep the exhaust flow going through the muffler...

How common is this sort of thing (failure of the flange weld on the exhaust pipes)? I'm thinking this is something of a fluke; at least I've never encountered it before... Is it repairable, or should I just count on replacing the pipe? I mean, it's going to have to come off anyway if anyone is going to try to re-weld it, so it may be just better to replace it... So, can anyone provide a part number for the exhaust pipe segment, running on the driver's side, from the just forward of the transaxle to the muffler?

 

[steveb01z06]

There are two bolts that hold those flanges together. You checked to make sure that they didn't loosen up?

Otherwise, yes, it can be rewelded. Maybe the weld was done late on a Friday afternoon and wasn't done correctly, I've discovered that some of the welds done on the 2001 chassis seem to be defective, so you're lucky it's only the exhaust and don't have a wheel coming off the car.

If you want a car as sturdy as a truck, you end up with a truck.

 

[compyelc4]

In our Vette club we've had a couple of C5's with the same problem. One was a '98 for sure and the other was an '03, I think. Re-weld?... certainly. Probably a bad weld. Seems like this would be kind of rare for stainless.

 

[BigJimZ16]

As far as replacing the pipe, keep in mind that from the factory, the pipe and muffler are a welded assembly an come out together. The car needs to be in the air with at least 4 feet of clearance so the assembly can swing through an arc. Also the rear sway bar needs to be disconnected from the frame mount. I'd try to get it re-welded in position. Good Luck!!

 

[gmjunkie]

As far as replacing the pipe, keep in mind that from the factory, the pipe and muffler are a welded assembly an come out together. The car needs to be in the air with at least 4 feet of clearance so the assembly can swing through an arc. Also the rear sway bar needs to be disconnected from the frame mount. I'd try to get it re-welded in position. Good Luck!!

Must be the difference in the pipe and muffler on a ZO6,on a lift my 03 Z-51 coupes mufflers will come off if you turn them right!

On a side note, at about 40,000 miles I had to remove and re-weld both sides of mine and the flanges on the intermediate pipe to!

 

[timfitz63]

There are two bolts that hold those flanges together. You checked to make sure that they didn't loosen up...?

Yeah. It's clearly the weld; the flange doesn't move when I rock the muffler back into it's correct position, but I can see the pipe and the weld rotating on the flange. It sheared off cleanly, pipe and weld together...

... If you want a car as sturdy as a truck, you end up with a truck.

Well, yeah. But my point was that the exhaust on my truck with 12 times the mileage -- and having endured more 'rust belt' winters than this C5 -- is still solid... And it's no more 'heavy-duty' than the C5 exhaust. This car has had an easy life, starting in the McDorman Collection, then into two private-owner garages; there's no real excuse that I can think of (short of a poorly-done weld, as "compyelc4" suggested) why this weld should have come undone... Sure, things break on cars; this one is just a little bit more aggravating, given the car's history...

As far as replacing the pipe, keep in mind that from the factory, the pipe and muffler are a welded assembly an come out together. The car needs to be in the air with at least 4 feet of clearance so the assembly can swing through an arc. Also the rear sway bar needs to be disconnected from the frame mount...

Thanks, Jim. It was almost a foregone conclusion that Murphy's Law would prevent this from being an easy repair (i.e., something I could do myself with a wrench and screwdriver laying under the back of the car on all four wheels)... :eyerole

I guess I'll have to get this repaired; I'm not even sure whether the older mufflers (without the chrome exhaust tips) are still available. While I like the look of the chrome tips better, I'd rather not put the newer mufflers on this car in order to preserve its originality. Plus then I'd have to replace both mufflers to keep it looking 'symmetrical...'

... I'd try to get it re-welded in position...

I'm reluctant to let someone re-weld it in place for fear of having them set the car on fire... :eek I can see the headlines now: "Senseless tragedy -- one of only fifteen Aztec Gold C5's in existence burned to the ground today in an accidental fire started by a careless welder... The car was a total loss; the owner was inconsolable..."

 

[BigJimZ16]

If you do remove the assembly to have it re-welded, make damn sure to have several reference marks at the flange to assure proper alignment when reassembled!! Nothing looks worse than the exhaust tips in different planes!!

 

[tankman]

Exact same thing happened to my '98.

I was going down the road and went over a bump (In Michigan we call them potholes -lol) and my exhaust became unwelded at the same place. It was quite loud when on the throttle.

After a few tries I realized I had to leave exhaust on car and work the alignment corrctly, then tack the tube to the flange with a weld. Then remove the muffler assy to achieve a good weld.

After a few years I replaced with aftermarket exhaust anyway.

Good Luck!!

 

[Huskerman]

Might be a good time to consider a catback Corsa set up....you would not hate the sounds.....

I did not know there were that few gold C5's out there.....wow!

 

[timfitz63]

Might be a good time to consider a catback Corsa set up....you would not hate the sounds.....

Yeah, were it not for the collectible nature of the car, I'd consider an after-market (or the later, chrome-tipped OEM exhaust) on it. Trying to keep it as original as possible...

... I did not know there were that few gold C5's out there.....wow!

Only 15 were made in 1998; mine's the final one. Another factory 'one-off' coupe in Aztec Gold was apparently made in 2003; it went straight into Kerbeck's collection (scroll almost to the bottom of the page to see some photos). Kerbeck also has Aztec Gold #7 in their collection -- the first of the three convertibles produced during the '98 production run.

 

[timfitz63]

Just to provide a bit of closure for this thread. While home in Pittsburgh over the Memorial Day weekend, I got Aztec Gold #15 out and took it to a local exhaust shop (Never-Rust on Ohio River Blvd.) that had been recommended to me by a neighbor of my parents; the neighbor is a Corvette aficionado, having restored several himself, and has used this shop in the past, since they specialize in stainless steel systems.

Anyway, I got it out there to Rob, and he fixed me up within an hour -- both sides of the exhaust (the right-hand side was starting to break loose). Rob admitted this was a common problem with the C5, but that he hadn't repaired many of them lately, probably because most folks had since replaced their stock exhaust systems with an aftermarket set-up of some kind. Anyone needing these kinds of repairs in the Pittsburgh area should visit Rob there at Never-Rust!