[Danirudo]

I have seen a few forum posts with the same issue as me with a few saying the sound is the torque converter and replacing it fixed the problem while others failed to find the cause of the noise.

I have a 2014 335i xdrive that is completely stock other than an intake

The sound is a knocking sound that only comes when the car has been driven and is also only really heard when in park or stopped (loudest in park or neutral). When in park or neutral, raising the revs makes the sound slightly louder and it increases with the revs of the engine. After around 1,500 rpm, the sound goes away. It isn't clear if that is because the engine drowns out the noise or the sound does actually go away. You can hear this in the second video linked below.

I first heard the sound roughly a month ago and when I went under the car it sounded like the noise was coming from the bell housing area. I then took it to two different shops, one being a German car shop and the other being a transmission shop. Both said that the noise was coming from the bell housing and not from the engine. The transmission shop said it sounds like it could be from the pump in the transmission while the other shop said that it is generally coming from the bell housing. The German specialist shop said that they did find videos of the same sound caused by a torque converter. Although both of these shops "think" they have an idea of what the problem could be, neither are sure and told me to monitor the issue. However, I want to fix the issue asap as a noise the car isn't supposed to be making cannot be good for it.

So I just wanted to know if anyone has experience with this and if so, what was the fix? It is not a horrible sound and as you can hear from the video it is not extremely loud, but definitely noticeable (its louder and more pronounced in person).

Side note: The technician said that the pump is directly beside the torque converter. In the video the sound may be hard to hear without headphones but it is a faint knocking/tapping sound.

video 1:

Video 2: https://www.youtube.com/shorts/IK_slV-We_o

[Turbof30N55]

Hi, I also have the same exact noise coming from the bell housing area. I recently mated a new rebuilt n55 engine to a ZF 8-Speed transmission. After start up I could hear a tapping noise thought it could be the new engine but wasn't and am now looking towards the torque converter or trans oil pump.

The noise starts as a tapping sound on start up. After the car warms up its changes tone and is more of a thud noise like in the video. The sound also almost goes away completely around 1500-1800 rpm and then comes back.

Was wondering if you or anyone has figured this out or can verify the sounds? I will be replacing the flex plate and torque converter soon.

Did you find the noise?

Thanks in advance!

[Netzke98]

I have a knocking noise from the bell housing. It’s a lot louder when the covers are off. I replaced the torque converter and flex plate. Took apart the transmission pump to inspect and it seemed fine. When the transmission was disconnected I couldn’t hear any knocking. Unfortunately I deleted that video. Still have the same noise unfortunately. This video is when the transmission is in park.
https://youtube.com/shorts/2P0ka9FVjQQ?feature=share

[Danirudo]

Originally Posted by Turbof30N55

Hi, I also have the same exact noise coming from the bell housing area. I recently mated a new rebuilt n55 engine to a ZF 8-Speed transmission. After start up I could hear a tapping noise thought it could be the new engine but wasn't and am now looking towards the torque converter or trans oil pump.

The noise starts as a tapping sound on start up. After the car warms up its changes tone and is more of a thud noise like in the video. The sound also almost goes away completely around 1500-1800 rpm and then comes back.

Was wondering if you or anyone has figured this out or can verify the sounds? I will be replacing the flex plate and torque converter soon.

Did you find the noise?


Thanks in advance!

Sorry for the late reply but it’s been about a year and still no fix. The noise has stayed the same so I am not too worried about it. Did you find the issue?

[Danirudo]

Originally Posted by Netzke98

I have a knocking noise from the bell housing. It’s a lot louder when the covers are off. I replaced the torque converter and flex plate. Took apart the transmission pump to inspect and it seemed fine. When the transmission was disconnected I couldn’t hear any knocking. Unfortunately I deleted that video. Still have the same noise unfortunately. This video is when the transmission is in park.
https://youtube.com/shorts/2P0ka9FVjQQ?feature=share

Thats interesting that a new TC didn’t fix it. Have you found the issue or did you give up like I did? lol