Engine rattling [Archive] - Bimmerfest - BMW Forums

: Engine rattling

06-20-2012, 01:14 PM
Hi guy,, i got a 2007 525i, I was wondering if anyone have any idea of what might be the cause of why my engine is rattling when the car is on idle, and I also notice that it gets worst when I turn the AC on... I thought that maybe the air filter was dirty but I took it out and cleaned it but it didn't make any difference... Please any advice will be truly apreciated..

06-21-2012, 06:03 AM
One of the pullies [on the drive belt] probably is making that noise. I'd guess the belt tensioner pulley must be making that noise; if not, the AC compressor.

One way to find out is to drop the belt, spin the pulley by hand and listen for noise or wobble.

06-22-2012, 09:37 AM
Is your car 525 or 535? I had a similar rattle on my 535 when idling. A small tap on the gas pedal would eliminate it. In my case the rattle was emanating from the passenger side of the engine bay. Check your brake lines. See if they are properly seated in the plastic holders - especially down where they are routed next to the engine.

06-22-2012, 09:43 AM
Thanks for your help guys....

06-22-2012, 09:56 AM
Is a 525i... Yeah I checked everything seems to be good and tied... I've also notice the RPM gauge is unstable it keeps dropping from 1/2 to almost 0 and it come backs up.. But for some wierd reason it the problem goes always when I turn the steering about a 1/4 of a turn on either direction and stabilizes the RPM and it smooths the engine

06-23-2012, 03:11 AM
I had a 2007 525i also and it used to have an engine tick noise which ended up being the valve lifter.

For reference you can search in Youtube for BMW Valve ticking noise/rattling noise and you will see a few vids. :p
Could be that also!