Exhaust leak and rattle with AA midpipe?

[Tommy L Garage]

I have a slight rattle at cold start. Checked it out this morning and it turns out there is a leak between stock downpipes and AA midpipe. The angle where they mate together doesn’t seem to be right and it leaks until the gasket material expands with heat. Anyone had a similar issue? It’s really embarrassing starting the car in the cold. I tried tightening the bolts but it didn’t help.

I’m thinking of just slapping an extra gasket on there. Thoughts ?

On that note - what are the part numbers for the gasket and new bolts?

Thanks!!
Tom

[MR RIZK]

IMO doubling the gasket won't help unless you sandwich another metal plate between them which still won't help you. Gaskets are not designed to be independently stacked.

Would be best to see if you can get the alignment better, this may mean u need to loosen the down pipes and mounting brackets to see if you get some wiggle in the correct direction for the mating surfaces to be more true.

BTW I'm speculating and assuming that the AA midpipe is fabricated correctly and there is wiggle room. Without being under the car hard to tell.

[mike@x-ph.com]

Recheck the install , we installed one on the shop's M4 couple weeks ago. Fits perfectly

[MisterF80M3]

I had the same issue:

https://f80.bimmerpost.com/forums/sh....php?t=1571115

The mid pipe can be installed without having to space the brace (although that is a common solution as well). During install, before tightening the ball clamps, we recommend using a small piece of wood or cardboard to space the midpipe between the brace. You can then tighten the ball clamps and remove the spacer. This will allow adequate space between the mid pipe and the brace when everything has been tightened down.