E90 Belt Squeal

[minh]

Hi Everyone

I am taking my vehicle in to have the belt replaced along with some other wear and tear items in a few days.

I am not paying BMW a grand just to diagnose if it is the belt or a pulley, I think that's really a bit of a rip off - so I have just instructed them to replace the belt without doing any "diagnostics"

Does anyone know here the characteristics of whether or not it is the belt itself or a pulley?

The characteristics I am experiencing are as follows:

It has been sprayed once before - squeal went away but then came back.

It always squeals on a cold start, then after a few seconds it goes away.

Sometimes it squeals after the vehicle has gotten wet.

I have noticed some cracks in the belt itself.

This all seems to me like it is the belt and possibly that it needs to be tensioned properly.

Any advice?

I am sinking like R15k into the vehicle now (4 new tyres, new brake discs and pads, including the replacement belt as well) so i really dont want to "waste" another 1000 on them diagnosing.

 

[Nick]

Here's what i did.
Took a can of q20 and sprayed each pulley until the noise went away.
then i ordered that pulley from imcomex and replaced it in my garage.

 

[husaindindar]

Hi.

I recall guys saying that the diesel e90s have a need for new damper pulley replacement at around 150k km.

It could cause belt issues if thats the case.

 

[minh]

Hi.

I recall guys saying that the diesel e90s have a need for new damper pulley replacement at around 150k km.

It could cause belt issues if thats the case.

Yeah I have heard so as well, though mine has just hit 120k km, I know one of the signs are hairline cracks in the damper pulley? mine appears to be fine when I checked it.

What I did yesterday is I put a bit of sunlight on the belt (tiny amount) and this morning when I started my noise is now gone.

After looking around online as all the other noises people have faced, the noise mine is making doesn't sound like a pulley squeal.

 

[Twincam Shark]

Here's what i did.
Took a can of q20 and sprayed each pulley until the noise went away.
then i ordered that pulley from imcomex and replaced it in my garage.

Hi 
do you spray the Q20 on the center of each pulley

---

Here's what i did.
Took a can of q20 and sprayed each pulley until the noise went away.
then i ordered that pulley from imcomex and replaced it in my garage.

Hi 
do you spray the Q20 on the center of each pulley

---

Here's what i did.
Took a can of q20 and sprayed each pulley until the noise went away.
then i ordered that pulley from imcomex and replaced it in my garage.

Hi 
do you spray the Q20 on the center of each pulley

 

[Nick]

yes, on the bearing.

 

[DJGyron]

I recently replaced the belt on a BMW X3 using an N53 engine. I noticed that the belt had sections where it showed some wear. After replacing it and starting up and letting the engine idle, I noticed the belt was not running flush on the tensioner pulley. It looked like it the surface of the pulley roller only gripped 75% of the width of the belt. It became obvious that it was the tensioner roller that also had some wear. After buying and replacing the old tensioner with a new one, it was perfect.

If you are experiencing some squeaking, best to also check the roller bearings on the idler pulley and the tensioner pulley. I replaced mine on my e46 m54 and everything seems alright.

 

[DarrylvanNiekerk]

The tensioner has a big spring in it that automatically creates the tension on the belt. The pulley on the tensioner seems to be a high wear point, mine has been making a lot of noise. When I took the serpentine belt off and spun the pulley I found quite a lot of play and it rattled a bit.

 

[Twincam Shark]

Hi Guys
It was just the belt that needed replacing, which shocking enough was still in good condition.