Snapped Serpentine Belt

[skmattwell]

Serpentine belt went pop today, luckily while I was pulling into my driveway! Obviously need to replace it, is this best left to the professionals?

Is it true you can get all the access you need from underneath via the floor panel?

 

[enuff_zed]

Which engine? m54 is pretty simple

 

[skmattwell]

Which engine? m54 is pretty simple

M54. Seen two methods, one removing the floor and two removing the fan. Then just a case of loosening the tensioner and feeding the new belt round?

 

[enuff_zed]

Which engine? m54 is pretty simple

M54. Seen two methods, one removing the floor and two removing the fan. Then just a case of loosening the tensioner and feeding the new belt round?

That about sums it up. Replace the belt for the aircon pump while you’re in there. Hardest bit is getting the routing right

 

[bigwinn]

V easy

17mm socket to release the serpentine tensioner
T50 to take the tension off the aircon

 

[skmattwell]

Which engine? m54 is pretty simple

M54. Seen two methods, one removing the floor and two removing the fan. Then just a case of loosening the tensioner and feeding the new belt round?

That about sums it up. Replace the belt for the aircon pump while you’re in there. Hardest bit is getting the routing right

V easy

17mm socket to release the serpentine tensioner
T50 to take the tension off the aircon

Thanks guys

 

[smorris_12]

Belt failure is unbelievably rare on these engines (I've got 276k on a similar generation M47). Check that the pulleys all run freely and the idler bearings haven't collapsed as a root cause for the belt giving up.

 

[j3nks79]

Belt failure is unbelievably rare on these engines (I've got 276k on a similar generation M47). Check that the pulleys all run freely and the idler bearings haven't collapsed as a root cause for the belt giving up.

This

 

[skmattwell]

Belt failure is unbelievably rare on these engines (I've got 276k on a similar generation M47). Check that the pulleys all run freely and the idler bearings haven't collapsed as a root cause for the belt giving up.

Sorry if it's a stupid question, but how would I tell if they have?

It's quite possible it's the original belt with 128k mikes on it

 

[j3nks79]

I would just replace the tensioner and pulley at the same time anyway. Good practise and not expensive

 

[skmattwell]

I would just replace the tensioner and pulley at the same time anyway. Good practise and not expensive

Have just ordered new tensioner and pulleys for the entire belt to be on the safe side.

Upon closer inspection it seems the pulley from the tensioner and the deflection puller just above it are way too close, almost to the point they are rubbing (even without the belt there). Wonder if this might have been the culprit

 

[DMike]

I would just replace the tensioner and pulley at the same time anyway. Good practise and not expensive

Have just ordered new tensioner and pulleys for the entire belt to be on the safe side.

Upon closer inspection it seems the pulley from the tensioner and the deflection puller just above it are way too close, almost to the point they are rubbing (even without the belt there). Wonder if this might have been the culprit

Without the belt they tend to be near each other. But as said above, good opportunity to inspect the pulleys and change them if there’s any wobble or resistance in them.

 

[9designs]

Jumping into this thread, today after a spirited drive I had loud shrill squealing noise from this area, got home, switched off, restarted 10 mins later all was okay again. Could this be I have a pulley bearing on the way out?
OEM or something AUTODOC has ?
Assume I need to take the fan out to make room?

 

[skmattwell]

Jumping into this thread, today after a spirited drive I had loud shrill squealing noise from this area, got home, switched off, restarted 10 mins later all was okay again. Could this be I have a pulley bearing on the way out?
OEM or something AUTODOC has ?
Assume I need to take the fan out to make room?

Not 100% yet but we're 99% sure that a failing water pump was causing my issue. After replacing the belt it was making all sorts of rattling noises and must have caused the belt to dislodge.

Given how easy it was to remove the fan and serpentine belt id recommend doing so and checking if any of your pulleys/tensioner has any play or unusual movement

 

[9designs]

Now I’m confused, I don’t seem to have the sprung loaded tensioner.

 

[smorris_12]

It just looks like a straight pulley. Put the breaker bar on the nut and make to tighten it and the belt should slacken.

 

[9designs]

Different layout.

Looks like the idle pulley has been deleted, looking at REALOEM,

Had my scope out and looking up behind the belt, does look like the tensioner, now I don't have big enough torx socket ! Plus is very corded, so might struggle to get a socket in.... suggests could be original.... hence the shrill bearing noise that's started.

 

[smorris_12]

The left hand one is the aircon pump. The lack of plain idler is because there's no power steering pump (I'd not thought about whether there was an idler earlier, the last few BMW engines I've played belts with have been M series.)

 

[Andrew Sheldon]

Just found out today my 2006 2.0 e85 has an Overrunning alternator pulley the likes of which can cause premature wear as well as noise from the belt, if it's 'free wheel' mechanism fails. Think most modern cars have them nowadays. Just another thing to keep your eye on...

 

[9designs]

Got it sorted last night..... I don't have the idle pulley.
The old belt was BMW, looked okay. The tensioner was well corroded, bearing seemed ok, nothing obvious. Suspect it was original at 127K miles. Access is awkward (from underneath) needed to unclip water house that runs in front of the crank pulley. Then work by feel.

No noises on test drive after.... fingers crossed it stays that way.