BMW 330i "ringing"noise from motor

haventrader, Jul 25, 4:44am
When the car is cold at idle, there is a sound like a bearing that's gone, coming from the engine. Once warmed up, and under acceleration, the sound reappears as though "ringing". It does not do this all the time.
As luck would have it, when I took the car to the BMW workshop I use, there was no trace of any sound. I was wondering whether it is the waterpump (this was replaced about 3 years ago as part of maintenance) or possibly the alternator! I'm not having issues with charging or heating issues. Has anyone experienced the same or any clues to what this might be! Cheers

thejazzpianoma, Jul 25, 4:47am
Its hard to diagnose from the couch but try turning the air conditioning on and off. The air con pump dosn't run all the time and a run bearing in that can cause such an intermittent fault.

doriandarby, Jul 25, 7:24am
I would put money on one of the three belt tensioners.There are two on the main alternator belt, one on the air con.They have sealed bearings in them that with age will lose their grease.

At least this is what was wrong with mine.

Best thing is to find a tame mechanic to take the belts off and find out which tensioner is worn.Repco sell them for approx. $60-70 each, or Milland on Trademe can sell them but you need to order the right ones (two of the tensioners are the same, the third is different).

doug207, Jul 25, 1:03pm
Belt tensioner, alternator or VANOS unit.

doug207, Jul 25, 1:04pm
Parts are easily had through bmwpartsworld.com or pelicanparts.com

the-lada-dude, Jul 25, 7:10pm
death nell !

stanandkath, Jul 25, 7:47pm
maybe, for a Lada :)

motorboy2011, Jul 25, 10:09pm
take the belts off and start it from cold, dont run it for long though. I did this on a car that had an awful belt squeal on acceleration not matter what i did to the belts. turned out it was an exhaust gasket, not the belts.

pfemstn, Jul 25, 10:50pm
could be flex plate if auto!

haventrader, Jul 26, 6:37am
Thanks guys for the advice. Definitely not belt squeal (if only it was that easy!) I'll spend some time on it this weekend and see if I can get to the bottom of it. Cheers

doriandarby, Jul 26, 6:57am
If you do take the belts off, try spinning each tensioner in turn.It should be free and quiet.Any notchyness and its stuffed.

zephyrheaven, Jul 26, 7:04am
Cam chain cha cha, kinda like a chain gun cha cha from most action movies of the late 80's - google them on youtube but imagine your wallet flying to bits instead of your puffer vest

patiki1, Jul 26, 7:55am
"ringing"noise,you didnt leave your phone on your engine by any chance!

haventrader, Jul 26, 8:52am
I was waiting for that one. Nah, Beemer's so reliable- never had to open the engine bay so could not have been my phone!

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