Cold Engine And Drivetrain Procedures; Alternator Belt - BMW R850 Maintenance Manual

Cold Engine and Drivetrain Procedures

Check Alternator Belt
Tools
T-handle hex – 4mm
Note: In most cases the alternator belt does not need to be checked any more.
Early models should have the pulley and belt upgrade that came out a few years
ago. Current recommendations are that the belt is installed and adjusted, then
not disturbed until 36K when replacement is specified.
1. Remove the four bolts holding the black plastic alternator belt cover at the front
of the engine, 4mm T-handle hex.
2. Remove the cover by sliding it straight down.
3. Check the belt for cracks or shredding.
4. Check the belt tension, quite tight, ~1/4" deflection when you press on the
center.
Note: Paul Glaves suggests that proper belt tension is when you can twist the
belt ~90 degrees, midway between the pulleys. If you can twist it more than 90
degrees, it is too loose. If you cannot twist it 90 degrees, then it is too tight.
5. Leave the cover off for the valve adjustment procedure on the next page.
Change Alternator Belt
Tools
T-handle hex – 4mm
socket – 13mm
ratchet
wrench – 13mm
torque wrench
1. Remove the four bolts holding the black plastic alternator belt cover at the front
of the engine, 4mm T-handle hex.
2. Remove the cover by sliding it straight down.
3. Loosen the 2 nuts and 1 bolt, 13mm, that hold the alternator – one is on top
and one is on each side, thus allowing the alternator to pivot down.
4. Remove the old belt. (Some bikes have a pipe that traps the belt – loosen it
enough to get the old belt out and the new belt in)
5. Install the new belt being sure it is properly seated.
6. BMW calls for a tensioning torque of 5.9 ft.lb. (8 Nm) on the adjuster bolt on
the left side of the bike. You have to get at this bolt from the alternator side and
you may have to lift the tank. Alternatively, you can pry the alternator up with a
large screwdriver to tension the belt.
7. Once the belt is under proper tension, tighten the 2 nuts and 1 bolt, 13mm, to
15 ft.lb. (20 Nm).
8. Check the belt for proper tension (see above) and proper seating alignment.
Parts
none
Parts

alternator belt

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