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Discussion Starter · #1 ·
2004 XC70 with 238k. I've been noticing a slightly louder exhaust noise over the last few months. I've had a couple people ask me if I have an exhaust leak even. From inside of the vehicle, it sounds like it's coming from below the radio. I put the car on ramps the other day while changing the oil and looked for a leak or hole in the exhaust, only to find none. All of the exhaust looks pretty decent with very little surface rust to speak of. I crawled under there with the engine running and I couldn't feel a leak or discern exactly where it was coming from. It sounds an awful lot like it's coming from the area of the flexible portion of the downpipe. Is it possible for that to leak without showing signs of wear or a hole? I really can't find a hole or rubbed area or anything anywhere. I have no CEL at all. I do get a very faint hint of exhaust on startup in the cabin, but no other time.
 

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Could be the exhaust manifold being a touch loose. Usually happens on the passenger side too...
 

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Very likely your exhaust manifold gaskets are leaking. Torquing them down won't do much good since the leak will have deteriorated the gasket. Look for black soot traces where the manifold meets the head.
 

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Discussion Starter · #5 ·
I did some more investigating today. I pulled off the outer heat shield and found it to be blackened with soot near the turbo to downpipe connection. On the downpipe itself, there is a white sooty deposit as well. I pulled the inner heat shield (the one that covers the exhaust manifold) and found no sooty residue. I did not attempt to torque the manifold bolts, however.

Does it seem likely that the turbo to downpipe gasket is leaking rather than the exhaust manifold? The turbo is what I hear a lot more of since the exhaust noise started.
 

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Discussion Starter · #6 ·
I fixed it. I did a good bit of reading and found information about a couple people having cracked downpipes at the flange that bolts up to the turbo. I took the entire downpipe off, which wasn't all that difficult, and found my downpipe had cracked and separated a bit from the flange. I could see my flashlight through the gap about 1/2 way around the flange. I put the downpipe on my welding table and welded it all of the way around to fix the crack, fill in the space, and stop any future separation. I also went ahead and ran a bead around the flange on the side that connects to the midpipe too since it was already off and on my table. I put it all back together and took it for a spin. The exhaust noise was back to normal and I had power again. I am pleased with the free repair (both gaskets were good enough to reuse) and I'm happy my car is back to normal again.
 
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