Engine - Timing Chain Whining Noise

GROUP 11
Engine

Bulletin Number
11 06 99

Woodcliff Lake, NJ
November 1999
Product Engineering

SUBJECT:
Timing Chain Whining Noise

MODEL:
E38 750iL with M73 engine

Situation:
A whining noise may be heard which is generated by the rotation of the timing chain at approximately 1000 - 1500 rpm at all engine temperatures.

Cause:
The timing chain noise is a normal engine operating noise which is transmitted to the body of the vehicle and into the passenger compartment via the engine, transmission and exhaust system mounts.

To reduce the amount of transmitted timing chain noise new mounts and engine mount vibration dampers have been developed for 750iL models with M73 engines produced up to 8/99. The new mounts were phased into production in 9/99.

Correction:
Only if a customer complaint is received regarding a timing chain whining noise at 1000 - 1500 rpm should the engine mounts, transmission mounts and center exhaust mounts be replaced a outlined in the procedure below.

Procedure:
Installation of engine mounts, transmission mounts and center exhaust mounts:

-- Remove the lower engine splash guard.





-- Loosen both left and right side engine mount nuts (right side show in illustration).

-- Remove exhaust system.

See repair manual group 18 section 1800 020.

-- Replace center exhaust mounts with new mounts, part number 18 21 1 745 426.

-- Replace engine mounts with new mounts part numbers: 22 111 092 824 (right side) and 2 111 092 823 (left side).

Repair tips: Remove upper section of both air filter housings and center plastic engine cover.

Remove radiator fan (see repair manual group 11 section 11 52 020) and the two lower nut on each engine mount.

Carefully raise front of the engine approximately 1 inch (25 mm) for appropriate clearance to remove and install the mounts.

-- Install new engine mount vibration dampers part number 22 11 6 750 246 on top of the new engine mounts. Tightening torque 31 ft.lb. (42 Nm.).

Note:
The new engine mount vibration dampers replace the original engine mount hold down nuts.

-- Reinstall upper sections of both air filter housings and the center plastic engine cover.

-- Reinstall radiator fan (see repair manual group 11 section 11 52 020). Tightening torque 29.5 ft.lb. (40 Nm.).

-- Support the rear of the transmission and replace the rear transmission mounts with new mounts part number 24 70 1141 545.

-- Reinstall exhaust system.

See repair manual group 18 section 18 00 020.

-- Reinstall the lower engine splash guard.





Parts Information:





Warranty Information:
Covered under the terms of the BMN New Car Limited Warranty.