Rattle Diagnosis

oldmanjingles · 07-26-2026, 01:17 PM

I have a rattle you can hear throughout the linked video most prominently around :30, 1:15 and 1:45.

Video here:

It occurs at low RPM underload, for example if I am in 6th gear at 40mph between 1200 and 3-4K RPM when accelerating. It is much more prominent when it is cold out. It goes away after the vehicle warms up, but not neccessarily with engine temp, when cold out it occurs for awhile after the oil is at operating temp and when its very hot (90+ F) out it may not occur at all.

There doesn’t seem to be a rattle you can hear outside the vehicle with the windows down, so it doesn’t track perfectly with the cowbell driveshaft noise, but I can’t entirely rule it out. It may also be the CV joint at the diff end of the driveshaft.

It also does not seem to be the dual mass flywheel either, as it goes away when put the clutch down.

The heat shields are all secure as well as the exhaust.

It seems to move around and can seem to come from somewhere in the front left dash, the passenger side door panels, the passenger side B pillar, or from the drivetrain tunnel. It sounds both like a plastic/interior rattle, but also seems to sound like a rotational rattle.

If anyone has any thoughts while I hunt this down that would be great. I can’t seem to find any posts that is exactly on point with this.

07-26-2026, 01:17 PM	#1
oldmanjingles New Member 0 Rep 17 Posts Drives: 2011 E90 M3 ZCP 6MT Join Date: Aug 2025 Location: Jacksonville, NC iTrader: (0)	Rattle Diagnosis I have a rattle you can hear throughout the linked video most prominently around :30, 1:15 and 1:45. Video here: It occurs at low RPM underload, for example if I am in 6th gear at 40mph between 1200 and 3-4K RPM when accelerating. It is much more prominent when it is cold out. It goes away after the vehicle warms up, but not neccessarily with engine temp, when cold out it occurs for awhile after the oil is at operating temp and when its very hot (90+ F) out it may not occur at all. There doesn’t seem to be a rattle you can hear outside the vehicle with the windows down, so it doesn’t track perfectly with the cowbell driveshaft noise, but I can’t entirely rule it out. It may also be the CV joint at the diff end of the driveshaft. It also does not seem to be the dual mass flywheel either, as it goes away when put the clutch down. The heat shields are all secure as well as the exhaust. It seems to move around and can seem to come from somewhere in the front left dash, the passenger side door panels, the passenger side B pillar, or from the drivetrain tunnel. It sounds both like a plastic/interior rattle, but also seems to sound like a rotational rattle. If anyone has any thoughts while I hunt this down that would be great. I can’t seem to find any posts that is exactly on point with this.
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