So Many Exhaust Leaks
Joe Angell
This video details how I repaired the exhaust leaks. It’s hard to hear the leaks in the video, but they’re really obvious in person.
My car got louder than usual recently. It manifested as a ticking sound coming from the engine bay. At first, I thought it might have been the tappets in the 3.0L engine. But then I had a friend drive it, and from the side of the road, it was very clear that it was an exhaust leak.
I have a very custom exhaust, with a combination of DPI headers, off-the-shelf catalytic converters, a Borla Pro XS muffler, and Car Chemistry silencers in the tail pipes. I had originally clamped it together, but I soon had an exhaust shop weld it to get rid of leaks from the clamps.
There are still two points that are bolted on: The headers to the engine itself, and the headers to the rest of the exhaust system.
Flange Leaks
I found a couple of immediate leaks. The gaskets for the headers to the rest of the exhaust showed signs of blow-by. These signs are black marks on the gasket mating surfaces.
The driver’s side wasn’t too bad, and I just needed to tighten up the bolts a bit.
The passenger side was quite horrible, with multiple dark black marks. It turns out that the flange ears were bent slightly, and this was keeping the gaskets from properly sealing.
The black marks on the mating surfaces are where the exhaust blew past the gaskets, indicating a leak.
I took the muffler off the car so I could try to hammer down the ears, and when that didn’t work I ground them down with an angle grinder. I thought about heating them and bending them back that way, but I’m not sure I have the tools to do that properly.
In the end, it still wasn’t enough — a light shone from behind still showed a gap between the gasket and the flanges. So I stuffed it with another gasket, which seemed to work.
Grinding down the ears of the flange to try to make a flatter surface for the gasket.
Light still leaking through from behind — the gasket isn’t sealing.
Header Leaks
But it didn’t fix the noise. It was clearly coming from the passenger side, so that left the header.
After loosening the bolts to flanges, I found that I could wiggle the header separate from the engine. The flange on the engine was still bolted onto the engine — it was just the pipes moving. The welds between the pipes and the flanges had failed.
I had this happen a few years ago on the driver’s side. A friend of mine was able to weld it back together for me, but I had some new TIG gear that I’d never used before and decided to try it myself.
My practice welds on some scrap didn’t work as well as I’d liked, but another friend Jeff, was able to come down and give me a hand. He had trouble with this too, but he got it done. I reinstalled the header and the leaks were gone.
I think the header failed because they only welded on the inside of the flange, and didn’t do anything on the outside. They were very nice, high-quality welds, but they were also very small welds. In both repairs, my friends welded on both sides to give them more strength.
The flange (bottom) is supposed to be welded to those pipes.
Thin Flange
Jeff noticed something else while we were putting everything back together — the flange that I’d ground down was really thin. I’m not sure how I didn’t notice that.
This was the exuse I needed to fix it properly. I cut it off and welded a new stainless steel flange onto the steel pipe. Since this was my first real TIG welding project, and after I tacked it into place in the car I pulled the muffler and welded the rest of it on the bench. It took me a couple of hours, and I burned through the pipe at least four times, which was solved with a lot of filler rod and a lot of grinding. It’s ugly, but it’s strong and works.
The header flange is good, butt he steel flange on the right is way too thin.
The old flange and the new one I welded on.
Tack welding the new flange before removing the muffler for final welding.
The exhaust leaks are now gone, and the car is back down to its normal amount of loud. And I learned how to weld stainless steel, sort of.