Engine - Drive Belt High Pitched Squealing Noises
SI M 11 02 05Engine
August 2009
Technical Service
This Service Information bulletin supersedes SI M11 02 05 dated August 2005.
[NEW] designates changes to this revision
SUBJECT
Drive Belt Noise
MODEL
R50 (Cooper), R52 (Cooper Convertible) with W10 engine produced from April 2005 to present
R52 (Cooper S Convertible), R53 (Cooper S) with W11 engine produced from April 2005 to present
SITUATION
The customer complains that the engine exhibits a high-pitched squeal from the engine accessory drive belt. The noise can occur at all engine speeds, but occurs mostly in the 2500 RPM range.
CAUSE
[NEW] Various possible causes
PROCEDURE
One of the following could be the root cause of the complaint. Please follow the procedures outlined below, in order.
1. Alternator Alignment
a. Loosen the 3 mounting bolts that attach the alternator to the mount two revolutions; do not remove the drive belt during this process. Leaving the drive belt in place causes a natural alignment of the alternator.
b. Retighten the bolts and torque to the specifications listed below for each model.
Cooper S (R52, R53)
Repair Instruction 12 31 020, Removing and installing/replacing alternator
M8 Bolts = 25 Nm
Cooper (R50, R52)
Repair Instruction 12 31 020, Removing and installing/replacing alternator
M6 Bolts = 10 Nm
Drive belt removal for MINI Copper S vehicles equipped with the W11 engine and F21 6-speed automatic transmission only
Removing the drive belt on a W11 engine equipped with the F21 automatic transmission requires modification to the current tool 11 8 410. The two dowel pins on the tool need to be shortened approximately 5mm. After the tool is modified, it can still be used on all of the models; a new tool will not be developed. Repair Instruction RA 11 50 020 will be updated in the September release on TIS to reflect the modifications necessary to fit this application.
2. Rust or Flaking Paint on the Pulleys
a. Inspect all pulleys for rust or flaking paint on the belt contact surface. Removal of the drive belt will be necessary - refer to Repair Instruction RA 11 28 010 (W10 engine) or RA 11 50 020 (W11 engine).
b. Using a 3M Scotch Brite pad or similar pad, clean the pulley until the rust or flaking paint is removed.
c. Before reinstalling the drive belt, inspect the belt for damage, foreign material on the contact surface, and length of the belt. Compare the belt length to a new belt from parts; replace as necessary, or reinstall the old belt.
3. The Drive Belt Hops or the Belt Tensioner Binds
a. Inspect the belt tensioner using the special tool to release the belt tension. Removal of the drive belt may be necessary; refer to Repair Instruction RA 11 28 010 (W10 engine) or RA 11 50 020 (W11 engine).
b. If the tensioner feels soft or appears to be binding, and will not reapply proper tension to the drive belt, replace as necessary.
c. Before reinstalling the drive belt, inspect the belt for damage, foreign material on the contact surface, and length of the belt. Compare the belt length to a new belt from parts; replace as necessary, or reinstall the old belt.
4. Supercharger Difficult to Turn (W11 Engine Only)
a. Under some circumstances, this could be caused by a difficult-to-turn or binding supercharger. Do not replace the supercharger. Submit a PuMA case to the Drivetrain group with "Belt Noise, Supercharger Binding" in the subject field, and wait for a response.
Note:
Under no circumstances should the drive belt be replaced with an aftermarket drive belt. If the vehicle is not equipped with a John Cooper Works Kit, then the special belt should not be installed.
WARRANTY INFORMATION
Covered under the terms of the MINI New Vehicle Limited Warranty.
Refer to KSD for proper defect code and labor allowance for work performed.