C250 W202 OM605 another squeaky/squealing idler pulley question

[purps]

Hello all,

I have a squeaking/squealing/screeching noise coming from the engine at idle. It disappears as soon as revs increase.

I cannot pin-point the source of the noise with a bit of hose to my ear, however when I press down on the idler pulley assembly with a bit of wood on the damper side (thereby forcing the spring on the other side to contract and pull the pulley up), the noise goes away.

From this information is it possible to know exactly what's at fault here? Damper? Pulley bearing? I am slightly puzzled as to why I cannot pin-point the noise with the hose.

The red in the attached picture shows where I was pressing with the bit of wood.

I also did a video in which you can hear the noise! Note that it looks like the idler assembly is gently rocking from side to side, but actually it is being shaken to sh*t (I guess the video frame rate is causing that effect).

https://www.youtube.com/watch?v=qjKWXQQxUFY&feature=youtu.be

Any help very much appreciated!

Cheers,
Matt.

 

[LexCorp]

The best way to diagnose is to simple remove the belt and rotate the pulleys by hand to see if they make a noise

 

[purps]

Thanks for the reply, I appreciate what you are saying.

I am really asking whether pressing down with a bit of wood as I described would silence a knackered pulley, or can it only be the damper.

Or should I just replace both as a matter of course.

Cheers,
Matt.

 

[spoton]

damper

Hello all,

I have a squeaking/squealing/screeching noise coming from the engine at idle. It disappears as soon as revs increase.

I cannot pin-point the source of the noise with a bit of hose to my ear, however when I press down on the idler pulley assembly with a bit of wood on the damper side (thereby forcing the spring on the other side to contract and pull the pulley up), the noise goes away.

From this information is it possible to know exactly what's at fault here? Damper? Pulley bearing? I am slightly puzzled as to why I cannot pin-point the noise with the hose.

The red in the attached picture shows where I was pressing with the bit of wood.

I also did a video in which you can hear the noise! Note that it looks like the idler assembly is gently rocking from side to side, but actually it is being shaken to sh*t (I guess the video frame rate is causing that effect).

https://www.youtube.com/watch?v=qjKWXQQxUFY&feature=youtu.be

Any help very much appreciated!

Cheers,
Matt.

instead of pushing down on the casting like you did push on the top of the damper as the bushes fail and can rattle, if the bushes have failed it could also explain your "shaking like ****" because as a result the damping wont be working

 

[spoton]

tensioner

if your tensioner assembly is moving from side to side (and not the usual up/down) it sounds like the bronze bush has gone on the pivot

 

[tim.100]

if your tensioner assembly is moving from side to side (and not the usual up/down) it sounds like the bronze bush has gone on the pivot

Mine did that on start-up. PCS put chalk on the belt to diagnose the problem; it was silent thereafter. Next step was to replace the belt (£27 from Eurocarparts, Continental part). On this one owner car, the belt was the original.

 

[purps]

spoton, thanks that is the sort of information I was looking for. I went out to have a play given what you said. I think the upper damper bolt is stripped. Not quite sure what to do with it now.

tim.100, thanks, but the belt is brand new.

Cheers,
Matt.

 

[purps]

Quick update: I repaired the thread with chemical metal and the bolt is back in and torque up very nicely. The squeaking is still there unfortunately, however it is slightly better I would say.

I guess I should replace the damper just in case it's the bushes that have failed. Of course I don't think we can rule out pulley bearings at this stage?

Cheers,
Matt.

 

[purps]

Just to round this off, it was indeed the damper.

Following the advice on this thread I took the belt off and turned everything by hand (apart from the crank!) and it all seemed OK.

Couldn't get the lower bolt for the damper out, but removing the pivot and pulling the whole assembly out was the solution. I used a 17mm sump plug (allen) key and a spanner for this.

There was some slight play in the pivot - the thrust washer at the back was a bit worn. Clean it all up, lightly greased, and flipped the thrust washer round so that the worn side was against the engine block. This improved things.

Thank you all for the help!

Cheers,
Matt.