Rhythmical thumping sound under the car at idle

[MentholGuy]

Hello guys,

My 2011 E90 M3 started making this weird sound recently.

You can hear the sound from this video, not the engine sound, but behind it.

I only can hear this sound and feel the very slight vibration at idle and is rhythmical.

Sounds like it's coming from spinning object, because it gets louder then quieter over and over but I don't hear it from the engine bay.

What could be? Mine is DCT by the way.

Please advise.

Thank you!

[tdott]

Need to rev it a little.

[MentholGuy]

Originally Posted by tdott

Need to rev it a little.

Thanks! I will get that video later today, but as I remember, that sound goes away when I rev or drive.

[MentholGuy]

Originally Posted by MentholGuy

Thanks! I will get that video later today, but as I remember, that sound goes away when I rev or drive.

Other video clip under the car with rev.

Thumping noise is like background music.

And this one is engine bay, that noise near the intake is normal?

[Helmsman]

Believe I have the same thump in the background, only hear at idle really. Think it always been there so hasn't worried me. You know for certain that it suddenly started, you didn't swop to a quiet exhaust system or so to start hearing it?

[MentholGuy]

Originally Posted by Helmsman

Believe I have the same thump in the background, only hear at idle really. Think it always been there so hasn't worried me. You know for certain that it suddenly started, you didn't swop to a quiet exhaust system or so to start hearing it?

I didn't really noticed this until recent, and have stock exhaust system (only resonator deleted).

I have changed engine and mission mounts recently though.

X-pipe leak could make this noise / vibration?

[Helmsman]

Originally Posted by MentholGuy

I didn't really noticed this until recent, and have stock exhaust system (only resonator deleted).

I have changed engine and mission mounts recently though.

X-pipe leak could make this noise / vibration?

Ouch, you lost previous engine?

[MentholGuy]

Originally Posted by Helmsman

Ouch, you lost previous engine?

No haha, I meant engine mounts and mission mounts

[Helmsman]

Originally Posted by MentholGuy

No haha, I meant engine mounts and mission mounts

Puh, that sounds better!

Lets see what the other guys chime in with reg the noise.

Cheers

Ps. Took a quick clip. Can't say that I hear much, but will try to remember to take another one while colder:

[E90FOUR]

Doesn't seem like the cause of this noise on a DCT car was ever identified, does anyone have any input on this?

Found another video with a similar noise from the interior (this one is 6MT, not DCT, but it's the same noise).

Thanks!

[E90FOUR]

Bump. Any ideas?

[JPSurratt2005]

Originally Posted by E90FOUR

Bump. Any ideas?

Maybe something on the driveshaft? There's a center bearing that could cause an issue, and a trans to shaft connecting guibo. Maybe something is loose/worn there.

[Ajolives]

I have the same, per what I read I thinks it's the throw out bearing making that helicopter noise. Goes away when I engage the clutch.

[E90FOUR]

Thanks for the responses. Have not been able to get underneath yet to inspect, but can check those joints. Interestingly, it is not constant but periodic at relatively consistent intervals. If it were the shaft I would think it would be a constant whirring. Also, I primarily hear it in the cabin, doesn’t seem to be present in engine bay or next to the car. It is relatively subtle, but present.

The sound does sound just like the helicopter noises of the TOB that I’ve heard. This is DCT though (does DCT have TOB or slave cylinder?).

Thanks!

[DrFerry]

Originally Posted by E90FOUR

Bump. Any ideas?

Long shot.... Wrong oil viscosity i.e. too thin. ? . The background thumping at idle sounds very similar to faint rod knock. IF the oil viscosity were too thin, then perhaps it might exacerbate low oil pressure at idle. Hence, faint rod knock being heard if the bearings are worn. Then as RPMs increase oil pressure increases and the faint rod knock disappears. Just my two cent theory.

[Ajolives]

Originally Posted by DrFerry

Long shot.... Wrong oil viscosity i.e. too thin. ? . The background thumping at idle sounds very similar to faint rod knock. IF the oil viscosity were too thin, then perhaps it might exacerbate low oil pressure at idle. Hence, faint rod knock being heard if the bearings are worn. Then as RPMs increase oil pressure increases and the faint rod knock disappears. Just my two cent theory.

There goes my good night's sleep, lol.

[Helmsman]

Originally Posted by Ajolives

There goes my good night's sleep, lol.

Hahaha, mine too!

[Erickuokwa]

I'm 6mt, I have that sound but when I press the clutch it goes away. How I keep check of unsure sounds over time is to see if the sound becomes irregularly louder or increasingly worse when I raise the rpm

[i.mc.m3]

Following this thread, I've been having the same noise for over a year now and can't find the cause. Does anyone have any updates on this issue and has it been resolved?

[jun_e92]

Originally Posted by i.mc.m3

Following this thread, I've been having the same noise for over a year now and can't find the cause. Does anyone have any updates on this issue and has it been resolved?

The same voice has been heard for more than half a year, but in the cabin, the reason has not been found. This noise makes me not want to drive! Late last year, during a series of operations to replace the oil filter gasket, a bolt under the engine protection plate was found to be loose. Finally found a solution to this noise!