Exhaust Manifold Question? Heat/Problems

[CobrayKid]

Hi
My exhaust sounds terrible. I took it to the shop and had the donut gasket and spring kits replaced. I even went under and looked and all the piping looks good. It was a little better, but still sounds like crap. The noise is coming from right under/behind the intake manifold so im guessing its the exhaust manifold. There is extreme heat behind my motor and the noise changes with throttle position, not RPM. Maybe plugged cat? Cracked manifold? Turbo problem? I can hear it spool. It gets worse when it gets hot, and when your easy on the gas it performs better, but once it starts getting loud it starts running like crap.

[tkelly27]

It could be the turbo to manifold mating area. That is normally fixed with a thin layer of axle grease, though I've never used any and never had a problem with that area leaking. I've never seen a gasket that would fit that. The turbo is a pain in the neck to remove while the head is on the car.

There is an exhaust manifold gasket, and they can leak.

When was the last time you changed your head gasket? I don't ask because I think you have a leak there, I ask because it's a pain in the ass job to get the turbo and exhaust manifold (and intake, it's an E/I gasket, 1 peice) off while the head is off the car. It takes twice the time and an act of God while it is on the car. Additionally if you break off a stud or put a gouge in something, you're going to be taking the head off anyways.

I've not seen a TD manifold crack before, even when they've been extensively ported. Clogged cats normally make your car feel like a dog 100% of the time. A pre-turbo exhaust leak can have a very dramatic effect on the performance of the car, especially one that's big enough to hear.

[detobias]

I had a leak at the 'turbo to manifold' mating area ; sounded like sh*t and leaked A LOT

the flange on the exh mani and the turbo must both be *flat* or you will get a leak ; there is no gasket

when I pulled mine apart I found indeed almost 1/8" gap - perhaps partly my fault since I had over-torqued the turbo-to-manifold nuts ; it took about 45 min. on a big belt/disc sander to get both flanges flat

then a nice film of axle grease and careful and patient re-assembly resulted in that nasty leak being fixed

but its a b*tch of a job ; as tkelly states; - you perhaps should plan to pull the head that way you can kill 3 or 4 birds with one stone ; hell, may as well also get a ported exh mani and swap on a Garrett while you're at it