S4 V8-4.2L (BHF) (2004)
Idler Pulley: Customer Interest
Engine - Drive Belt Whistling/Jarring Noise
27 Whistling and jarring noises from belt drive - 4.2L MPI
13 10 05
2018230/4
July 1, 2010
Supersedes Technical Service Bulletin Group 13 number 10-02 dated June 14, 2010 for reasons listed below.
Affected Vehicles
Condition
Noises from the generator ribbed belt drive.
^ Whistling noise at cold start from the ribbed belt idler roller at about 1600 rpm.
^ Jarring noises from the ribbed belt tensioning roller when accelerating from low rpm range.
^ Whistling noises at 2800 rpm.
Technical Background
Whistling noises through poorly lubricated idler roller bearing.
Jarring noises through decreasing tensioning torque of the tensioning roller.
Whistling noises of the belt tensioning roller bearing because of poor lubrication.
Production Solution
Modified idler and damper roller bearing lubrication.
Service
1. Inspect generator and crank shaft pulley for misalignment or damage. Repair as necessary.
2. Before removing ribbed belt, mark the direction of rotation using chalk or felt tip marker.
3. Replace damaged ribbed belts.
4. With whistling noises during cold start, check the idler roller and replace if necessary.
5. If idler roller is replaced, the idler roller bolt and protective cap must also be replaced.