Engine - Serpentine Belt Damage
SI B 11 09 08Engine
July 2010
Technical Service
[NEW] designates changes to this revision
SUBJECT
Alternator Drive Belt Broken
MODEL
E82, E88 (1 Series) with N54 engine up to 4/08
E90, E92, E93 (3 Series) with N54 engine up to 4/08 except xi models
SITUATION
The models listed above utilize a single serpentine drive belt for the power steering pump, alternator, and air conditioner compressor. During normal driving, the front engine mounts allow the engine to move slightly on the front axle carrier. However, under extreme conditions, such as driving at high rates of speed over curbs or speed bumps, the engine movement can result in the serpentine belt or power steering pump pulley contacting the front engine carrier. If this occurs, the belt and/or pump pulley could be damaged.
PROCEDURE
When diagnosing a complaint related to a broken drive belt or a drive belt which has come off the pulleys, it is important to carefully examine the power steering pump pulley for any signs of damage.
1. If there is no damage to the pulley, continue with normal troubleshooting.
2. If the pulley is chipped or cracked, then the pulley and the belt must be replaced.
3. In cases where the pulley has been damaged, the front axle carrier should be examined for any signs of contact in the area below the power steering pump pulley.
4. If the axle carrier has any sign of contact, then the carrier must be replaced. For E90, E92, and E93 vehicles produced up to 3/19/07 which require replacement of the front axle carrier, the left side engine support (P/N 22 11 6 760 317) must also be installed.
The following sections of the Repair Manual should be referenced, depending on the repair(s) which are to be performed:
^ Repair Instruction RA 32 41 100 "Removing and installing/replacing belt pulley on vane pump for power steering"
^ Repair Instruction RA 31 11 001 "Replacing front axle carrier"
^ Repair Instruction RA 22 11 110 "Replace left engine support arm (N54)"
PARTS INFORMATION
WARRANTY INFORMATION