C 3500 Truck 2WD V8-6.6L DSL Turbo VIN 1 (2002)
Crankshaft Main Bearing Seal: All Technical Service Bulletins
Diesel Engine - Crankshaft Rear Oil Seal Leaks When Cold
Bulletin No.: 03-06-01-008
Date: February 27, 2003
TECHNICAL
Subject:
Crankshaft Rear Oil Seal Leaks During Extreme Cold Weather Operation (-29°C/-20°F) (Modify Oil Separator)
Models:
2002-2003 Chevrolet and GMC C/K Models
2003 Chevrolet and GMC C4500/5500 Models
with 6.6L Duramax(TM) Diesel Engine (VIN 1 - RPO LB7)
Built Prior To January 31 2003
Condition
Some customers may comment on crankshaft rear oil seal leaks during extreme cold weather operation. Typically -29°C (-20°F) and below.
Cause
A restricted positive crankcase ventilation (PCV) system may be caused by frozen condensation, ice, or snow that has accumulated in the vent tube at the
bottom of the generator bracket. In extreme cold weather, the vent tube may not be subjected to enough heat from the engine compartment to melt the ice
or snow. Excessive crankcase pressure may develop and cause premature oil seal failures. While the oil leak may occur anywhere on the engine, the
crankshaft rear oil seal is the most susceptible due to the larger surface area in which crankcase pressures can act upon. The excessive crankcase pressure
may not be apparent in the shop as the vehicle warms up and the blockage in the vent tube thaws.
Correction
Create a secondary atmospheric vent path for the PCV oil separator housing using the following procedure. This location is protected from the elements
and is not subject to freezing. A secondary atmospheric vent path was implemented to production in February of 2003.
1.
Remove the generator bracket. Refer to Drive Belt Tensioner and Generator Mounting Bracket Replacement.
2.
Remove the positive crankcase ventilation (PCV) oil separator cover bolts.
