Glad to help and that we were able to isolate the rattle to the tip itself.

 

Updating this post with a resolution. As others have stated in this post, I had a exhaust bracket break on my left side. Today I had it welded on for $50 at Morehouse Welding in Milford, Ohio, great guys.

My local Porsche garage actually found the issue while I was having my oil air sep replaced.

Thanks for everyone's input on this forum.

 

Good for you to finally resolving this rattle. Rattles drive me nuts.

 

I have an exhaust rattle that only comes on when I press down the clutch or at light gas pedal pressure.
Drives me nuts!

 

You sure it's an exhaust rattle? Odd that it's related to the clutch being depressed although that could create a vibration slightly different enough to create a rattle. Might also be a noisy throwout bearing. How many miles on your clutch?

 

I think it's the muffler, but who knows ...
Have about 40k miles on the clutch. I'll try to pinpoint it more this weekend I think.

 

Maybe pick up one of those automotive stethoscopes from one of the local stores. Not only will it help you to pinpoint the source of the noise, but it's pretty cool to hear what's going on in different parts of the engine.

 

Dragging this thread back from the dead as I have the same sort of issue...

I started hearing a tinny rattle at my the rear of my '06 C2S about 10 days ago. It always started at low rpms and ended quickly, but it was loud and made me cringe, especially if I was in a parking lot and especially if there were people around and (God forbid) ESPECIALLY if they happended to be car people. With work and all, I really didn't have the time to look for the problem so I parked the car and worried until I got a chance to track the rattle down.

I had a buddy listen at first while I slowly revved the car. We found is that the rattle was happening around 950 rpm as I got on or off the throttle lightly. The second thing my buddy found was that the sound was eminating from the area of the right exhaust tip(s) and if he put inward pressure on the tip the sound stopped. I got to the back of the car and found that a tab between the inlet tube to the muffler and the middle exhaust tube (I have a PSE exhaust) had cracked all the way through and was scraping against the inlet tube just enough to make me think something was failing on my clutch

Now here's some craziness, I put a magnet to the parts and the inlet tube is completely non magnetic, but the outlet tube is lightly magnetic (including the tab). Perhaps there was some embrittlement from the welding process or just the stress at the weld. The tab broke right before the weld bead and there seems to be a fairly large load on the tab against the tube, hence the rattling. Though I'll take it at 190k miles

Gotta find me a welder this week to fix the problem.

You can see the separation inside the circle. Exhaust is Ferritic Stainless and intake is Austenitic S.S. from what I can tell.

 

It seems unlikely that they would source two different specs of stainless, but its possible. But there could be another reason. Depending on the alloy used, austenite formation can occur in the 600-800C temp range. With exhaust gasses in the 950C range, its possible that a phase transformation is occuring upstream of the muffler, that the muffler is enough of a heat sink that it doesn't happen downstream.

 

That sounds pretty reasonable to me and probably explains why the break happened at the weld on the upstream side.

 

This has happened on both my earlier 996 and on the 997, on both sides.
I'd say it's not a question about if but when it will happen.

 

I checked the other side and there is some cracking so I'll have both sides welded.

 

Thanks for sharing this.....

Note to self, when feasible, no matter the rattle, just remove the suspected part.

From the get go, you suspected the tips. If first thing you would have done after tightening the tips, is remove them, you would have found within seconds that the removal of the tips took care of the problem.

 

It wasn't the tips, it was the pipes to and from the muffler. There is a tab welded between the two pipes that cracked. That tab was scraping against the upstream pipe. One of the pipes is attached to the tips.

This seems to be a quite a common occurrence with these cats. If I was to hear it again, I'd just check the welded tabs first.

 

Just an update...pulled the mufflers (since I live in Arizona it was very easy, no seized nuts) and took them to my uncle so he could weld the one tab I saw. He actually found 5 different cracks and now all of the screeching and scraping sounds are gone. I called around town for repair and the minimum I could find was $160, that was for actual stainless welding. Too rich for my blood and luckily I remembered that my uncle was airframe certified. Just cost a trip to visit my favorite uncle and lunch. Plus he taught me some fundamentals of TIG welding. That was a good day.