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Discussion Starter #1
Hello,

I've just had the oil pan gasket replaced on my 2006 525i (N52 engine). That went well, but now I have increased noise transmission from the engine compartment into the cabin. It seems to be coming in from the area behind the instrument cluster, through the firewall or maybe through the ventilation ducts. For example, I can hear the starter more loudly than before, and also the engine itself. I can even hear other unrelated external sounds such as my neighbor running his lawn mower. It's as if a conduit for noise has been opened.

Could a seal or plug in the firewall have gotten nudged during the oil pan gasket replacement? Like maybe the entry point for the steering column?

Interestingly, a Google search turned up an old thread from October 2015 on 5series.net. Someone from Panama had exactly the same symptoms after an oil pan gasket replacement, just like me. Unfortunately, there were no replies to that thread. Any ideas?

Thanks,
cinergi
 

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How did you replace the oil pan gasket? Did the engine come out or just raised, or removed suspension? I know it was a pain for the E39 but not sure about E60.
 

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Discussion Starter #3
How did you replace the oil pan gasket? Did the engine come out or just raised, or removed suspension? I know it was a pain for the E39 but not sure about E60.
It was a big job that I didn't tackle myself; my indy did it. I wasn't present, but he said he had to remove the crossmember. I don't think the engine had to be lifted.

-cinergi
 

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So the engine was supported from above, hanging. Lifted the car and removed the subframe.
He didn't need to touch any sound insulation on the firewall. And I guess you have already checked the cabin air duct.

Missing jack support can give some whistle but don't expect more noise coming from there #11

http://www.realoem.com/bmw/enUS/showparts?id=NE53-USA-02-2006-E60-BMW-525i&diagId=51_5196

And I assume you checked for missing underfloor coating

http://www.realoem.com/bmw/enUS/showparts?id=NE53-USA-02-2006-E60-BMW-525i&diagId=51_5211



missing wheel well linen #17

http://www.realoem.com/bmw/enUS/showparts?id=NE53-USA-02-2006-E60-BMW-525i&diagId=41_1470

Maybe check the fire wall if there is anything not plugged well

http://www.realoem.com/bmw/enUS/showparts?id=NE53-USA-02-2006-E60-BMW-525i&diagId=41_1546

I doubt any sound isolation was removed

http://www.realoem.com/bmw/enUS/showparts?id=NE53-USA-02-2006-E60-BMW-525i&diagId=51_5147
 

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maybe the rubber boot around the steering (where that thick red cable is. starter is right there)

 

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Discussion Starter #6
Thanks acoste. I did indeed check the cabin air ducts (both sides) and the underfloor coating - present and accounted for! I didn't check for a missing wheel well liner since this didn't occur to me; I will do so after work, but based on the sound I don't think that's it.

I also spoke with my indy on the phone; based on my description, the only thing he can think of is the rubber boot around the steering that you also mentioned. This had also occurred to me actually, since it's near the bottom of the engine and the subframe.

Guess I'll have to take it in again to confirm, since that boot must be checked from the bottom (can't see clearly from the top).

Thanks
cinergi
 

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Discussion Starter #7
Update: My indy and I checked the steering shaft boot as well as other potential holes in the firewall but we didn't find anything out of place. Rather than continue troubleshooting this issue, I've decided to leave it. I've realized that I actually like the noise; it is very subtle (my indy couldn't hear it) and not intrusive, and I like hearing the engine a bit :). Its effect is similar to the "noise generators" included with certain BMW models (e.g. Z4) that deliberately pipe some intake noise into the cabin to sound more sporty :). Or the F10 M5 whose audio system actually plays engine noise through the speakers, LOL!

-cinergi
 
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