Hello my name is Sam, welcome to Just Answer.
Does this noise only happen when it's warm?
Does it happen at any particular RPM?
Were the drive belts re-tensioned after replacement?
Did you check to see if any of the pullys were noisy when the belt was off?
Did this problem start to happen after the described repairs?
On a scale of 1 to 10, how loud would you say the noise is?
The belt tension is adjustable with the adjuster plate. Take a look at the instructions below.
drive belt.
I just wanted to make sure the adjuster plate was set up for maximum tension.
Really, any of the pulleys or even the accesories (alternator, power steering pump) could possibly make a noise like you describe. When trying to diagnose a noise like this, I use a mechanics stethascope to pinpoint where the noise is comming from. You can use a length of fuel hose in the same way, just be very careful of the belt while the motor is running.
Usually is one of the ideler or tensioner pulleys is starting to fail, they will leak grease that can be seen when the pulley cover is removed.
BMW Master technician
BMW S.T.E.P. graduate, 10 years BMW dealership experience
Let me know!
Thank you!