Annoying exhaust rattle. Any pointers?

ube91 · 11-29-2023, 01:12 PM

Hi all,
So my M2C has been having a slightly annoying, embarrassing rattle emanating from the muffler area for my last two months of ownership. It's most prevalent at a cold start and when driving at lower RPMs with the valves closed. It is not really noticeable after the car is warmed up and in Sport Plus.

About few weeks into ownership, I took the car to Precision Sport Industries here in Orlando where they looked at the car for an inspection. They had adjusted the midpipe (car came with an AA single midpipe) and had told me that the source of the noise was from a missing exhaust hanger and bracket on the right side of the car, near the differential.

Ordered said parts and installed it, (Had to special order from Germany) which did absolutely nothing to stop the issue. While I had the car up in the air I used a small mallet and banged around at various points on the muffler to try and isolate where this rattle might be coming from. Couldn't find anything so I just gave up and decided I'll have it looked at when I go in for an upcoming service in December.

However after this, the valves began making a struggling sound whenever they opened or closed. It is most noticeable when in accessory mode and when changing from Efficient to Sport Plus, which opens and closes the valves. Maybe I banged a little too hard on the muffler and knocked something loose?

Maynard · 11-29-2023, 01:43 PM

The valves in the exhaust diverters are known to go bad (I think actually the springs or rods actuating them) - not every car, but I think they warrantied them if it happened early enough. Do an online search, there may be a simple fix (cheaper than replacing them). Might be s/t else, but this is a likely option.

11-29-2023, 01:12 PM	#1
ube91 Enlisted Member 81 Rep 33 Posts Drives: 1991 318i, 2019 M2C, 2000 Z3M Join Date: Sep 2021 Location: Orlando, Florida iTrader: (0)	Annoying exhaust rattle. Any pointers? Hi all, So my M2C has been having a slightly annoying, embarrassing rattle emanating from the muffler area for my last two months of ownership. It's most prevalent at a cold start and when driving at lower RPMs with the valves closed. It is not really noticeable after the car is warmed up and in Sport Plus. About few weeks into ownership, I took the car to Precision Sport Industries here in Orlando where they looked at the car for an inspection. They had adjusted the midpipe (car came with an AA single midpipe) and had told me that the source of the noise was from a missing exhaust hanger and bracket on the right side of the car, near the differential. Ordered said parts and installed it, (Had to special order from Germany) which did absolutely nothing to stop the issue. While I had the car up in the air I used a small mallet and banged around at various points on the muffler to try and isolate where this rattle might be coming from. Couldn't find anything so I just gave up and decided I'll have it looked at when I go in for an upcoming service in December. However after this, the valves began making a struggling sound whenever they opened or closed. It is most noticeable when in accessory mode and when changing from Efficient to Sport Plus, which opens and closes the valves. Maybe I banged a little too hard on the muffler and knocked something loose?
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11-29-2023, 01:43 PM	#2
Maynard Colonel 3848 Rep 2,873 Posts Drives: 228iX & M2C Join Date: Mar 2016 Location: Upstate NY iTrader: (1)	The valves in the exhaust diverters are known to go bad (I think actually the springs or rods actuating them) - not every car, but I think they warrantied them if it happened early enough. Do an online search, there may be a simple fix (cheaper than replacing them). Might be s/t else, but this is a likely option.
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