General B57 service belt

ORSO · Dec 1, 2024

today while checking the engine I noticed that the service belt is marked. The cause seems to be the tensioning pulley. Does anyone else have experience with this? I currently have 20,000 km on the clock.

Shopkeep · Dec 2, 2024

ORSO said:
today while checking the engine I noticed that the service belt is marked. The cause seems to be the tensioning pulley. Does anyone else have experience with this? I currently have 20,000 km on the clock.

That tensioning pulley looks nasty, I have 13,000kms and here are my belt & pulley (quite hard to photograph)

Tinerfeño · Dec 2, 2024

Can't say what has caused the scratches on the (plastic?) tensioner pulley but for me it doesn't look dangerous. But should be followed.

Shopkeep · Dec 2, 2024

I would be more concerned about the belt than the pulley, those gouges in the pulley surface look to have been made by something stuck in the surface of the bellt. Maybe the belt has a flaw at some point or might be delaminating, definitely worth getting the dealer to inspect.

NQ94 · Dec 2, 2024

The only time I have seen similar marks on pulleys is in QLD wet season when we get lots of mud and grit into the engine bays and the serpentine belts may fray and separate the outer edges or split the belt pulling through the pulleys and sometimes feeding into the alternators and pump seals. On some of our remote roads we get mud that's not really fluid, full of small sharp rocks, sticky clay but not thick so it goes through everything and accumulates under cars and trucks and can build up on the engines and radiators leaving only holes where the drive shafts and rotating parts pass through. We wash cars and some equipment every couple days to stop overheating. Never worked in snow so I don't know if the same issues are suffered in northern hemisphere winters.

Greasemonkey · Dec 2, 2024

I have the same scratches on my diesel engine. On the pulley they are approximately 1 mm deep. Traces of wear can be also seen on the outside of the belt. All other pulleys are ok. At the moment it's not a problem. But you have to keep an eye on it.

ORSO · Dec 2, 2024

thanks!

How many km do you have on the clock?

did you notice it now or has it been like this for a while?

Greasemonkey · Dec 2, 2024

I have now driven 17700 km. No river crossings and no mud. I noticed it for the first time today based on your pictures. I couldn't find anything today that could have caused the scratches. Heavy rain? Thrown up stones? In any case, I will order a replacement belt and a replacement pulley.

ORSO · Dec 2, 2024

I also intend to change the tensioner and belt.
Now I have activated my service center to understand if I can do it under warranty. Otherwise I will go to the official BMW that I have behind my house.
I just hope it is not complicated to replace the tensioner, but it seems to me that there is enough space to work on it.

Greasemonkey · Dec 2, 2024

I think you could even change the belt and pulley on the go, if you have the tools with you. There are also several YouTube videos on how to change a belt on a B57. The panel in front of the belt can be easily removed. (5 dowels)
The belt fittet in my car is a Conti 8 PK 1122 EPDM

ORSO · Dec 2, 2024

can you post some videos about it?

Greasemonkey · Dec 2, 2024

For example:

View: https://youtu.be/bPYU9r09gCU?si=fVf4_Z2rF2dB4AZO

Greasemonkey · Dec 3, 2024

I think I've found the cause of the grooves on the pulley. They are probably caused by the black hose clamp on the opposite hose. (see picture) If you press the hose with the clamp towards the pulley, the scratches correspond exactly to the corner of the hose clamp. I noticed months ago that the hose was getting too close to other parts, so I fixed it with cable ties and a piece of foam insulation. The scratches were probably already in the pulley at this point, but I didn't see them because of the darkness. At the next inspection in May I will try to convince my dealer that this is a design fault that should be repaired under warranty.

ORSO · Dec 3, 2024

I just checked that tube and actually the clamp could be the culprit for those marks.
in my case however that tube had been fixed as soon as I brought home the grenadier and it is very fixed and does not move easily. moving it by hand I can barely get it close to the pulley but for sure it does not touch it. probably in movement however it will come to touch it.
I think that first I will turn the clamp 90° as indicated in yellow in order to move the two ends away from the pulley and then I will put some rubber on for protection.

Greasemonkey · Dec 3, 2024

The scratches on my pulley are exactly identical to yours. Maybe they appeared in the first few kilometers and we just didn't notice them. My hose is now also well fixed, but when I force it towards the pulley, the scratches correspond to the edges of the clamp. Turning the clamp over is a good idea. If it was the clamp that caused the scratches and not, for example a small stone in between, then one can be pretty sure that the belt has not suffered any damage. But I will definitely get myself a spare one.

ORSO · Dec 7, 2024

Work done: I rotated the clip to the right and covered it with rubber to be safe.
on the offending tube about 30cm from the clip I found a loose clamp not connected. This is probably the cause of the interference.

ORSO · Dec 29, 2024

Has anyone else with a diesel checked to see if the belt tensioner is interfering with the tube? After turning the clip I keep finding signs of interference. I think that tube needs to be redesigned to run further away.

can you post some pics from your IGs to see how that tube goes? Thanks

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