R 350 BLUETEC (251.125) V6-3.0L DSL Turbo (642.870) (2010)
Crankshaft Main Bearing: All Technical Service Bulletins
Diesel Engine - Crackling/Ticking Noise At Idle
Engine makes noise, ticking/crackling
Topic number
LI03.20-P-048278
Version
2
Design group
03.20 Crankshaft
Date
02-22-2010
Validity
Model series 211, 219 with OM 642
Model series 164, 251 with OM 642
Model series 203, 204, 209, 221, 461, 463 with OM 642
Reason for change
Work steps updated.
Reason for block
Complaint:
The engine makes ticking/crackling noises at idle speed and at speeds up to approx.1500 rpm
Notes:
^ The noise occurs from mileages of approx. 20,000 km (aprx. 12,000 miles) or after an oil change.
^ Noise is clearly noticeable in area of 1st crankshaft main bearing.
^ Noise can no longer be heard when the poly-V belt is removed.
^ It is essential that the problem noise be compared with the example noise listed.
^ Noise is not regular. Pulsed crackling noises occur at irregular intervals; compare reference noise in attachment.
^ 20 pulses (ticks) that could potentially be the cause of complaints can be heard in the attached reference noise.
Attachments
Cause:
Run-in effect of 1st crankshaft main bearing.
Scope of testing:
Remove/install poly-V belt.
- Compare reference noise. (When doing so, run engine without poly-V belt)
Note:
If the ticking noise is still present after the poly-V belt has been removed, the bearing shells of the 1st crankshaft main bearing are not defective. Proceed
further to determine the cause.
If the ticking noise is no longer present after the poly-V belt has been removed, the bearing shells of the 1st crankshaft main bearing are defective. The
bearing shells of the 1st crankshaft main bearing must be replaced.
Remedy: