2003 BMW 745 2003 E65 BMW 745i engine squeeling noise

NAVBMWE65

MEMBER
2003 BMW 745
V8
2WD
AUTOMATIC
101,000 MILES

Hi, I seem to have a squeeling noise at the front part of the car like a belt is slipping. The noise is definately from the area that has the belts. This noise only happens when the engine is warm, it only happens when im coasting or at stanstill. If I rev the engine the noise stops, however on allowing the car to idle again it comes back.
The noise seems to slightly lessen when the AC is switched on. Also if I turn the engine off & then switch it on straight away the noise dissapears for a very long time, but again reappears later once engine warms up and car is stand still or when i'm coasting & not touching the accelerator pedal.
It's driving me mad, could it be a belt/pulley/belt tensioner or AC belt problem?
As I say it only happens when engine is warm, when accelerator is not being pressed & MOST IMPORTANTLY it totally stops if I turn engine off & then restart it again.

5 Replies

DOCHAGERTY

MECHANIC
9,601 POSTS

You have made a reasonable and quite possibly correct diagnosis.

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Tuesday, April 13th, 2010 AT 4:30 PM

NAVBMWE65

MEMBER
2 POSTS

Dear Sir,
Thank you for your speedy response. I will get my friend to take a look at the belt drive systems asap. Could you tell me which system it is most likely to be causing this noise eg AC/alternator etc.
Your input is gratfully recieved.

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Wednesday, April 14th, 2010 AT 12:43 PM

DOCHAGERTY

MECHANIC
9,601 POSTS

That will be the determination of the technician. It could be any of them.

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Thursday, April 15th, 2010 AT 8:10 AM

OZ540

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1 POST

I have the same problem with my 745I. What did you have to replace?

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Saturday, May 19th, 2012 AT 6:11 AM

RIVERMIKERAT

MECHANIC
6,110 POSTS

Both of you, try this to determine the exact source of the squeal:

Purchase a 2-3 foot length of 1/2 tubing. With the engine running and making the squeal, hold one end of the tubing against your ear and slowly move the other around the various moving parts of the belt drive system. When you hear the noise the loudest, you're right over the squealing part that needs to be changed.