Serpentine belt shredded when idling

[Kal81]

Hi all

Need some help with an issue in my A Class 2007 1.5 W169 (petrol).

The serpentine belt came loose recently whilst I was driving. Power steering, ABS etc stopped working but managed to get it home safely as I wasn’t far.

My mechanic fitted a new belt but it got shredded again once he started it when it was idling. The belt he first replaced was covered in oil and partially shredded through the middle. Car had been leaking some oil. I noticed the leak on my driveway when I drove it away. Oil spots.

I’ve heard there can be a leak on the tensioner but my mechanic said he couldn’t see any oil leaking from there. He said that he’s going to change the tensioner and idler pulley tomorrow. Should this stop the belt from getting shredded again? Any ideas where this oil leak may be coming from? Coolant, oil levels all fine and was driving fine until belt snapped.

Thanks.

 

[pcthrillrider2]

maybe one of the pulleys has seized

 

[ToeKnee]

maybe one of the pulleys has seized

That could certainly be a cause and I'm surprised that any competent mechanic wouldn't have checked all pulleys, idler wheels and tensioners for problems before fitting a new belt. I guess the pertinent part of that is "competent"!

 

[slade1]

Agree with ToeKnee, find another garage/.mechanic.
Probably idler pulley on the way out, change it and tension pulley.
Had this problem with CLK years ago.

 

[Petrol Pete]

Doesn't explain the oil though . Assuming it is engine oil . Crankshaft front seal ??

 

[noogieman]

Could also leak from oil test port in front of the engine, this squared rubbery gasket is just above the belt tensioner.
These cars do they have issues with harmonic balancers like previous MB's use to have in the past?

 

[ALFAitalia]

Normally if a belt shreads within a few minutes of starting it's not been fitted correctly and the belt was slightly off the side of one pulley....don't ask me how I know! It could be a siezed pulley but that would be obvious when fitting.....and they are not so oil sensitive that if would fail so fast....it would take ages and be slipping a long time before it failed.

 

[Kal81]

Doesn't explain the oil though . Assuming it is engine oil . Crankshaft front seal ??

It is engine oil. Yes, crankshaft front seal or from the upper valve cover due to a rubber gasket gone bad.

 

[Kal81]

Are these the two pulleys I need? Pictures below.

 

[E55BOF]

Normally if a belt shreads within a few minutes of starting it's not been fitted correctly and the belt was slightly off the side of one pulley....don't ask me how I know!

I found out the same way on the CLK...

 

[noogieman]

Are these the two pulleys I need? Pictures below.

Buy pulley from these brands INA, Gates or SKF or genuine MB part

 

[IanW]

Before you start, check the bolts used to retain the pulleys - the M113 engine uses a Torx T50 security bolt on the tensioner pulley. The bits are not widely available. Not something to discover halfway through the job.

Ian.

 

[markjay]

maybe one of the pulleys has seized

This would have been the first thing to be picked up when replacing the belt for the first time.

I'm wondering if the aircon compressor seizes up occasionally?