Exhaust Leak

I had more noise coming from the front of the car than is normal, and not the right noises. Cars make happy sewing machine noises at the front and burble noises at the rear. Or they should.

I went underneath, looking for a leak. There was nothing obvious. So I removed the splash shield under the engine to view the downpipe. I put the car up on the quick jack, locked it in place and then started the car, letting it idle while I crawled under it. I like using a piece of paper to find leaks, it will blow around or make noise when air hits it. There are lots of ways to do it of course, just don't burn your hands on a hot exhaust pipe.

I found the leak on the high side of the flex coupling near where the downpipe connects to the catalyst pipe. it didn't seem like that much trouble, at first.

Looking for replacement pipes, the Audi part runs around $1,100. I found an aftermarket one for about $125 but it's NLA or backordered into next year as far as i can tell. That leaves custom making something or buying a performance downpipe. My fab skill sucking as they do, I went with the latter.

ECS makes a really nice stainless steel downpipe that is TIG welded. It does not have the resonator that the stock pipe has, so the car will emit up a little more noise. Nothing objectionable though. It is also 3" in dia, larger than the stock pipe, which should help with breathing. Finally it is also very nicely priced.

5 bolts, should be easy, right? lol.

The two bolts at the rear were not too bad. Two rounds with penetrating oil and the bolt blaster took care of those without drama. At the front though, we had a situation. The stock pipe has 3 studs built in to it, and the nuts go on from the far side (towards the engine) This makes them harder to get to, and also removes the option of knocking them out with a hammer.

The nuts had deteriorated so much there was nothing to put a wrench on. I would have cut them all off, without damaging the flange where it attaches to the catalyst pipe. That part took hours. The You Tube folks whose videos I watched either didn't attempt this (they removed the catalyst pipe along with the downpipe) or they cut the section where they get the 3 nuts off. Maybe one(?) of the videos had a car with so little rust on it that the operation was not bad. You can reach at least one of the nuts from the engine bay using a wobble and a long extension, if the nut is intact. But I live in the northg eastern US, and the rust on parts of these cars is really hard to believe.

A screenshot of the Audi parts diagram, taken from FCP Euro’s website. Part 15 is the downpipe, 17 is the gasket to the catalyst pipe and 19 is the coupler to the next section of the exhaust.

Looking up at the flex coupling and it’s studs/nuts. You can see the nuts are just gone. I was able to cut two of them off and get a good enough cut into the 3rd that I was able to break the remains off. But it was not quick or easy.

Looking down at where the catalyst pipe will bolt to the downpipe. After I cut off the nuts I ground down the last bits of bolt and then cleaned the area up with a dremel using a wire brush attachment. All in, not too bad looking.

The new ECS downpipe is truly a thing of beauty. The kit includes hardware, the reducer you need to connect to the stock exhaust and the 2 clamps that go with it.

The old pipe. I was able to break it off fairly easily up where the flex coupling hasd rusted. This made access to the bolts easier.

Here is the new pipe in place. They supply bolts and brass lock nuts. I used high temp neverseize on them and then had them face the bottom of the car to make it easier to cut them off someday or hammer out the bolts. Hopefully neither is necessary, but always do a solid for future you, or the next owner.

wide angle of the new pipe in place. If I was a smart person I would have done the transmission mount insert at the same time, but it’s no big deal. "Ahl be bahk."

another view of the new pipe in place. It fits perfectly.

The menagerie of tools I would up needing. PBlaster and Bolt Blaster for rusty bolts I could reach. S-wrenchs are key for exaust work, VW/Audi seems to assume you have them. If you’ve ever replaced the exhaust manifolds on a Beetle you know. Crowbar & screwdrivers to wedge in between the 2 pipes and help break that last bit of the last stud. Dremel with a cutoff wheel took care of one stud, the sawzall got another. Special mention to the expanding trim pliers that make working with all the plastic rivets a piece of cake. (bottom)