Low vibration/rattling at idle
Hello, everyone. My '03 325I M54 (90K miles) has a sporadic, low-pitched vibration/rattle at idle (~700rpm or less).
The vibration started immediately after I replaced gaskets for the valve cover and oil filter housing assembly (due to small oil leaks). It's a very low-pitched sound/vibration and kind of sounds like it's coming from inside the engine, although I can't be sure. I've put a stethoscope all over the easily-accessible parts of the engine, but can't pinpoint any source. The sound/vibration only happens sporadically at idle (more often when A/C or PS is engaged), and it never occurs above idle. You can hear the sound best either inside or underneath the car--less so when working under the hood due to pulley/belt/etc noises. No warning lights on the dash and no trouble codes from my OBD scanner. I think it has to be associated with the gasket replacements I did ... but I'm at a loss as to what the problem might be. The car runs very smoothly otherwise.
Appreciate any advice. Thanks.