Drive Belt Tensioner: Service and Repair

11 28 020 - Replacing tensioning device for alternator drive belt (N52K)





Special tools required:
- 11 3 340





Important!
Aluminium-magnesium materials.

No steel screws/bolts may be used due to the threat of electrochemical corrosion.

A magnesium crankcase requires aluminium screws/bolts exclusively.

Aluminium screws/bolts must be replaced each time they are released.

Aluminium screws/bolts are permitted with and without

color coding (blue).

For reliable identification:

Aluminium screws/bolts are not magnetic.

Jointing torque and angle of rotation must be observed without fail (risk of damage).





Necessary preliminary tasks:
- Remove drive belt





E9x only:

Remove special tool 11 3 340.

Release screw (3) on belt tensioner (4).

Tightening torque 11 28 1AZ 11 28 Ribbed V-Belt with Tension and Deflection System.

Installation Note:
Replace aluminium screws.

Remove belt tensioner (4).





E85, E89 only:

Remove special tool 11 3 340.

Release screw on belt tensioner (1).

Tightening torque 11 28 1AZ 11 28 Ribbed V-Belt with Tension and Deflection System.

Installation Note:
Replace aluminium screws.

Remove belt tensioner (1).





Assemble engine.