serpentine belt squeal on cold start -06 530i n52 119k miles
 

Loud squeal noise from the serpentine belt on cold start up. Goes away after 20 seconds or when the engine warms up.



Engine has 119k miles, is it one of the pulleys or the belt slipping?

What's your service history on serpentine belt, tensioner? If they haven't previously been changed renew all.... fcpeuro.com offers kits with all you will need.

Never serviced...going to order it.

You are aware how serious this is right? Don't put this off.

When the belt comes off, it can wrap around the crank pulley, get so tight is pushed through the front seal then destroys the engine.

yep!! there are many threads out there regarding this.

I was doing trans oil, pan, and gasket change also. Might as well do the belt while the car is sitting. Going to check the alternator bearings, make sure it spins freely.

I was reading/watching some installation instructions and realized how important it is to 90 degree angle torque the belt tensioner bolt after its been torqued to 25nm.

Did the serpentine belt with pulleys..no more squeal.

The belt is riding on edge of the new tensioner pulley, unlike the old which was about 2mm inwards towards the engine. I didn't get chance to make a comparison between the old and the new tensioner to see if the pulley sits more flush with the tensioner.