Drivetrain - Troubleshooting Noise and Vibration
TO: OUR MERCEDES-BENZ PASSENGER CAR DEALERSREF. NO. 41/18
DATE: April 1995
SUBJECT:
ALL MODELS
DRIVETRAIN NOISE AND VIBRATION
This Service Information provides information and procedures on a systematic troubleshooting of complaints regarding drivetrain noise and vibration.
Particular complaint types have been categorized by the various speeds/conditions at which they may occur in order to isolate the specific trouble source and to provide a specific remedy procedure.
A. Humming/droning from approx. 50 mph and faster In all driving conditions.
B. Vibration from approx. 38 mph and faster in all driving conditions.
C. Vibration from approx. 38 mph to approx. 68 mph under load only (acceleration/deceleration).
The above noted speed ranges may vary slightly up or down depending on vehicle model.
Since drivetrain complaints may be influenced by various outside factors, a thorough test drive on a smooth road surface is critical in order to verify the complaint within the specific speed range.
CAUTION!
We recommend that the vehicle be throughly inspected, the engine oil level must not be overfilled and the tires must be inflated to the proper inflation pressure prior to beginning the test drive.
Obey all speed limits and practice safe, courteous driving.
Vibration, humming or droning may be the result of:
^ Tires out of balance.
^ Tires with a "saw tooth" tread wear pattern.
^ Flat spots on tires due to long periods of parking.
^ Variations in the radial stiffness of the tires.
^ Excessive radial or lateral runout of tires and wheels.
^ Tires of excessive age.
Additionally, humming and droning may be attributed to the engine, drive shaft imbalance or improper drive shaft angles, along with the transmission or rear axle center piece.
Please use the following troubleshooting charts to further verify the cause and determine the remedy to resolve the complaint.
Order No. S-SI-41/18
Parts Information
Part Name Part Number
Vibration damper 124 350 06 72
Bracket for fuel pump 124 478 22 40
Installation hints
1. Support rear axle center piece from underneath as necessary. Remove rear axe center piece mount hex. head bolts from the rear axle center piece mount at rear axle carrier. Install vibration damper, part number 124 350 06 72 (Figure 1) onto the rear axle center piece mount of the rear axle carrier along with hex. bolts (62b, Figure 1) removed priorly. Arrow (oben) must point up (Figure 1). Torque rear differential mount hex. bolts.
Tightening torque: 150 Nm
2. Bracket, part number 124 478 22 40, must be installed in order to reposition the fuel pump (Figure 2).
Figure 2:
a = Mounting holes for fuel pump
3. On vehicles with ASR, remove production VSS sensor cable mount bracket with sensor cable clamps (A, C, Figure 4) from rear axle carrier.
4. Modify production VSS sensor cable mount bracket as shown (B, Figure 4). Install modified bracket onto the rear axle carrier as shown (Figure 3). Take care to route sensor cable and re-secure with prior removed cable clamps (C, Figure 4) into the new locations.
Location of modified VSS sensor cable mount bracket.
Damage code information
The damage code has been increased by one digit in order to provide specific information needed for quality improvement in series production. Therefore, we request that the damage code entered be accurate to the complaint verified and diagnosed.