Hello

I have a 2005 R53 JCW and I've noticed a metallic rattling sound coming from the s/c.

I checked it closer today and basically, the thin piece of metal which comes out of the tensioner - which has holes in it (which we use to holes to determine how tight / slack the tension is on the S/C belt) has broken off - and is vibrating / rattling around within the tensioner coil spring.

What I am trying to determine is

• Is this a serious issue / do I need to fix it ASAP / not drive the car
• Is this tab (with holes in it) purely used for visual purposes to check belt tension...or does it have another function

The reason for asking is that I have a track day in 2 days time and there is no way I can get this fixed by then...

Since noticing it, I have done ~100 miles, without any issue - at RPMs upto redline.

I had my S/C belt (and pulley) changed less than 200 miles ago - so the belt is less than a week old.

Hope this video explains better

Any help / suggestions much appreciated

 

Why do you think that tab is 'broken?' I suspect that the damper in your tensioner is worn out. But the primary purpose of those holes is to provide a means by which the tension is released so that the belt can be changed and/or removed. Once the tension is released with a tensioner tool, a pin is inserted into one of the holes. Do a search on this forum and you will understand.

 

Yes I understand the tab is to do with tension, but mine is completely detatched - ie I can pull the whole thing out and hold the tab in my hand - it isnt actually connected to anything

 

Ah, now I understand. The broken tab won't affect anything, although it will make it difficult to remove the belt next time you want to service it or any of the items it drives.

 

Theoretically (and worse case), can he cut the belt and then remove/replace tensioner afterwards. He'll need a new belt but i guess that's easier than trying to release tension and slipping belt off at the same time.

 

I ended up needing a new tensioner assembly.

The belt went really slack and started making this awful noise so I got the car to my local BMW (slowly!) and had a whole new unit fitted.

All good now!

 

Out of curiosity, how many lashes did they administer to you for that job?

 

It was £300 all in, so not too bad.