2001gti exhaust leak

Not open for further replies.


New Member
i have a 2001 GTI with a large exhaust leak inside the engine compartment. Where can it be coming from, it fills it up in seconds. Where an it be coming from?
Is it filling with water or smoke? Water it could be a hose or welch plug that rotted out. If it's smoke it could be one of the couplings/joints.

#35, 29, 22, 42, 43

I'm thinking one of the exhaust pipe welch plugs is corroded through, these are aluminum plugs welded in place after casting the manifold.

It might also be a case of water trapped in the pipe during winter froze, expanded and cracked the pipe?

Sad story, A guy brought his boat by here just today said he parked it over winter and neglected to winterize and forgot to remove the drain plug. Motor was sitting under water all winter which may have saved it from freeze cracking, I'm sure the result won't be good... ugh!
Last edited by a moderator:
I just started it on the trailer and the exhaust seems to be coming from the back. I reached back as far as I could to the outlet rubber hose. It is VERY soft, I can squeeze it almost flat. My arms aren't long enough to feel the back. Could it have burned a hole thru it? If so is this any way normal? Is the exhaust cooled with water spray in the header to keep the rubber cool?
Yes, water must be mixed with exhaust just after leaving exhaust manifold, water is injected in two locations to avoid unsafe heated objects in the bilge. If the exhaust cooling water injection is disrupted (clogged cooling line or device) water injection will be insufficient to keep exhaust components from becoming unsafely hot, rubber hoses and plastic exhaust parts will melt as well.

Also over the decades, rubber hoses will rot and delaminate due to hydrocarbon chemistry and the natural deterioration of rubber components, it's a pretty harsh environment thus water injection into the exhaust stream helps cool and keep things from becoming "unglued".
Ok, if the rear exhaust hose needs to be replaced it looks lick the body top must be removed, is this the case and how difficult is that?
You can do a engine running test with it still on the trailer. Back it down a lake ramp enough to have the intake grate under water. Still securely tied down on the trailer. Start it up and let run. Feel the exhaust components for heat after 5 min. They should be just warm. look for the exhaust leak. Check all the cooling lines. I had a small one, with a hole in it where I could not see it. Filled hull with water about 2 inches. Tuned pipe ran hot. The Welch plugs are welded in to cover casting holes. The corrode thru all the time. A high school welding shop can fix it cheap. Or a professional welding shop.
I have had mine done for $50 each pipe at my Wife's high school. The tuned pipe can be $700 - $1,000 if you can find one.
Last edited by a moderator:
What is entailed in replacing the rear exhaust hose? Will the ski need to be separated to get to the exhaust ? It looks like it's to far to the back. Any suggestions?
Not open for further replies.