[JuniorMint335]

2007 335i Stock motor @ 100k.

I am hearing this knocking sound from cylinders 1,2,4. The car came back a week ago from a head gasket job. In doing so they also replaced all the exhaust valves including a couple lifters because the mechanic accidentally damaged 2 valves. I didn't notice anything unusual until this afternoon when I opened the hood and heard this sound coming from the top of the engine. Now the sound is clear enough that i can hear it even with the hood is closed.

After I came home, I took the engine cover off and felt each coil pack and immediately noticed cylinders 1,2,4 were more shaky than the others. It feels like something is hitting it. I took the sparkplugs off and examine each one, they are looked fine. I then tighten it back and started the engine again, the sound persisted. Next I swapped the coils from the good cylinders to 1,2,4, only to find out the same result. Then I noticed when I press onto the latch of the coil on cylinders 1,2,4 the sound goes away. I can't make sense of this.

When I finally decide to call it a day and put everything back together, miraculously the sound fainted, but I can still hear a little bit. Can anyone tell me what the heck is going on??


Link below for the actual sound before I started my diagnostics.

Thanks in advance.

[hankcah]

If I'm hearing the same sound, that consistent door-knock sound, sounds close to mine, that I posted here - http://www.e90post.com/forums/showthread.php?t=1238335

Interesting about the coils. I replaced my spark plugs and coils back at 80k miles, and I'm at 103k miles now. Not sure if ours sound 100%, yours seem like a metronome, but could just be the length of the video. Mine isn't as consistent but same noise/sound.

Let me know what you found out. Has the noise gone away? Did you replace your coils / all 6 or just the 3?

Mine is currently at the shop and I'd hate for it to be just that. I'd rather just bring my tools to the garage parking lot and re-adjust the plugs and coils themselves.

Hope it all worked out okay. Thanks

[JuniorMint335]

Originally Posted by hankcah

If I'm hearing the same sound, that consistent door-knock sound, sounds close to mine, that I posted here - http://www.e90post.com/forums/showthread.php?t=1238335

Interesting about the coils. I replaced my spark plugs and coils back at 80k miles, and I'm at 103k miles now. Not sure if ours sound 100%, yours seem like a metronome, but could just be the length of the video. Mine isn't as consistent but same noise/sound.

Let me know what you found out. Has the noise gone away? Did you replace your coils / all 6 or just the 3?

Mine is currently at the shop and I'd hate for it to be just that. I'd rather just bring my tools to the garage parking lot and re-adjust the plugs and coils themselves.

Hope it all worked out okay. Thanks

Turned out mine had some defected spark plugs. The ceramic (white part) of the plug was spun. Although it was still attached but the inside was loose so everytime it gave a spark the plug bangs on itself, which is why it quiets down when i press onto the coil.

I changed all the plugs and the problem went away. I hope this solves your issue too.