Alternator Belt

MiloG

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My bike has noise coming from behind the alternator cover especially on a cold start, a slight spray of silicone lub takes it away so assumed the belt needs replacing as the bike a 1150 GS 03 model has 33k on it, however on removing the cover the belt seems to be in good condition, is this the norm and should I just replace the belt anyway.
 
I would have thought that if the noise was caused by the belt slipping, then silicone will make it slip worse but quietly!
If you've got the cover off anyway I'd clean away all traces of silicone and replace the belt anyway for peace of mind
 
Last edited:
The belt simply needs adjusting. Loosen the three 13mm alternator adjusting bolts/nuts and lever up the alternator so get the correct tension then retighten nuts.
 
Thanks for the advise, how important is it to have it tensioned at the 8NM. The bike has done 33k, at what mileage should they be changed.
 
MiloG said:
Thanks for the advise, how important is it to have it tensioned at the 8NM. The bike has done 33k, at what mileage should they be changed.
Click to expand...

It’s really important, you must buy the factory tool and get it spot on, or the bike will disintegrate,

Or you can just twist the belt and see how far it goes, and make it slightly tighter than that.
 
MiloG said:
Thanks for the advise, how important is it to have it tensioned at the 8NM. The bike has done 33k, at what mileage should they be changed.
Click to expand...

I've still got my alternator belt in use after more than 10 years. The one prior to this frayed and needed replacing after just three years. The tension is checked easily by pinching the belt between your finger and thumb and twisting it. If you can twist it 90 degrees its too slack. I can twist mine about to just under 45 degrees and it runs sweet and true. I carry a spare in my pannier just in case because if it goes you are pretty stuffed. They are cheap and weigh next to nothing and its a relatively simple roadside fix if necessary.

Not sure what you are doing with that silicone spray but keep it away from the poly belt. It won't fix anything.
 
1a66c5bb9273116bc2547c5b303a9f46.jpg


Seems like pretty good guidance to me. I was concerned before a big trip as I seemed to have developed a slight ‘squeaking’ from cold on start up. Checked the belt and it looked like new and was tensioned ok following the guidance above.


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Silkolene Classic 20W50 4 litre

My 1150 GS is due to have the engine oil changed, what’s your thoughts on using Silkolene Classic 20W50 4 litre
 
Confused....as ever

Hi All

My Haynes manual suggests that the Alternator belt and pulley was changed to a "lifetime" belt. Yet some seem to be saying that they need to be changed every 3-5 years, is this just the older bikes that haven't been changed to the new belt/pulley set up, or is the phrase "life time" not to be taken too literally!
 
theoneandonly said:
10 years ?

mine last 3-3.5 years .
Click to expand...



Beak Freak said:
Hi All

My Haynes manual suggests that the Alternator belt and pulley was changed to a "lifetime" belt. Yet some seem to be saying that they need to be changed every 3-5 years, is this just the older bikes that haven't been changed to the new belt/pulley set up, or is the phrase "life time" not to be taken too literally!
Click to expand...

My 1150 GS Adv is 15 years old and I have owned it from new, I have never changed the belt yet in its 35910 miles

However, as a precaution and going by the BMW schedule I will change it in 90 miles time at the 36k service

It doesn't squeak and the alternator light isn't on, whether it's frayed remains to be seen
 
Mine isn't at the mileage point yet, but it is 20 years old. As you say no problems, but I was wondering if it is the belt that it creating an annoying whine (which I thought was the fuel pump..still not sure on that one!).

I may just check the adjustment as Steptoe suggests and try to get some lube onto the alternator bearing.
 
Beak Freak said:
Mine isn't at the mileage point yet, but it is 20 years old. As you say no problems, but I was wondering if it is the belt that it creating an annoying whine (which I thought was the fuel pump..still not sure on that one!).

I may just check the adjustment as Steptoe suggests and try to get some lube onto the alternator bearing.
Click to expand...

Video the whine?
Post it here
 
Haynes manual seems to imply that whine on start up is to be expected.......see note 2 below
69e28397752b35311c7cb7b959bc6737.jpg



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From the OE service manual
Renew Poly-V belt *)
renew Poly-V belt every 60 000 km (36 000 miles); do not adjust

Leaving it longer risks failure as below.
The thread has been known to wrap around behind the lower pulley and tear up the hall sensors.

 
GS Addict said:
From the OE service manual
Renew Poly-V belt *)
renew Poly-V belt every 60 000 km (36 000 miles); do not adjust

Leaving it longer risks failure as below.
The thread has been known to wrap around behind the lower pulley and tear up the hall sensors.

Click to expand...

That’s an old out of date service schedule. BMW changed the recommended belt life in 2005 to 24k miles/ 5 years .
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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