bimmer boy 21 Report post Posted December 4, 2009 m54b30 making a screeching noise only when hot. Sounds like metal on metal (may not be metal on metal) It only does it when the engine rpm is just a fraction below normal idle, so when like standing still in gear (auto) or with the ac and all the lights on. You can sometimes just hear it when its on normal idle but its not very loud. the sound is coming from under the oil filter housing (checked with a stethoscope). The sound is not a slipping belt, and it can not be a bad pully bearing because the sound is instantly gone as soon as u rev the engine up about 50-100rpm from where its making the noise. It sounds like something internal under/arround the oil filter housing. Oil used is Castrol Edge sport 0W-40. Oil filter used is genuine BMW. This seems to be a very common noise as from a brief search on the net a lot of people have this problem but no solution. Heres a couple of links as to what it sounds like (very similar) http://forum.e46fanatics.com/showthread.php?t=674351 http://www.youtube.com/watch?v=mburPOPF6FI...player_embedded Thanks Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted December 4, 2009 I could have a look next week... does sound like its the alternator tensioner or idler bearing though. They do what you describe. Take the belt off if you know how and run it... see if the noise goes away. Quote Share this post Link to post Share on other sites
