| Subject: | Oil Leak Under Extreme Cold Temperatures (-34°C (-30°F) or Colder) (Install Vented Oil Fill Cap) |
| Models: | 2004-2005 Buick Rainier |
| 2003-2005 Cadillac Escalade Models |
| 2003-2005 Chevrolet Avalanche, Express, Kodiak, Silverado, SSR, Suburban, Tahoe, TrailBlazer, TrailBlazer EXT |
| 2003-2005 GMC Denali Models, Envoy Models, Savana Van Models, Sierra Models, Topkick, Yukon Models |
| 2003 Isuzu NPR/NQR Commercial Models |
| 2003 Work Horse Custom Chassis |
| with 4.8L, 5.3L, 5,7L or 6.0L Gas Engine ( VINs V, M, T, P, B, Z, G, S, U, N -- RPOs LR4, LH6, LM7, LM4, L33, L59, LS1, LS6, LS2, LQ4, LQ9) |
Condition
Some customers may comment on an engine oil leak under extreme cold temperatures (-34°C (-30°F) or colder). The customer may also comment that there may be some oil seepage out of the engine oil level indicator (dipstick) and/or out
of the front or rear crankshaft seals during engine operation only.
Cause
Under extreme cold temperatures (-34°C (-30°F) or colder) and extended driving conditions, the PCV system may experience a freezing condition and shut off all crankcase gases to pass through the PCV system. This may cause crankcase
pressure to rise steadily and, in some cases, this high pressure unseats (pushes out) the oil level indicator from the indicator tube and causes an oil leak during engine operation.
Important: If a visual inspection indicates that oil is still leaking from the front or rear crankshaft seals after this bulletin has been performed, then further diagnosis must be performed using the Oil Leak Diagnosis and/or Crankcase
Ventilation System Inspection/Diagnosis in SI. Refer to the following SI document number(s) in this bulletin and print a copy for further assistance in diagnosing this condition.
| • | Oil Leak Diagnosis (Truck) (SI Document ID #204344) |
| • | Oil Leak Diagnosis (Car) (SI Document ID #1406822) |
| • | Crankcase Ventilation System Inspection/Diagnosis (Truck) (SI Document ID #1246823) |
| • | Crankcase Ventilation System Inspection/Diagnosis (Car) (SI Document ID #954724) |
Correction
Follow the service procedure below for diagnosis and correction of this condition.
- Inspect for the oil fill dipstick being pushed out of the dipstick tube and that there is engine oil seeping out when the engine is under operation. This condition could be caused by the PCV valve freezing shut.
- If an icing or freezing condition is found with a PCV valve inspection, then replace the oil fill cap with a vented oil fill cap.
- Use a new vented oil fill cap, P/N 12589430. A vented oil fill cap will regulate the crankcase pressure between 15 kPa and 18 kPa. This will prevent the over pressurization of the crankcase under the freezing conditions of the
PCV system. Once the PCV system thaws out, the crankcase gases will pass through the PCV system and normal crankcase pressure will be restored.
- Inspect the engine oil level . Start and operate the engine under normal conditions and visually inspect that the engine oil leak has been repaired. If another engine oil leak has been detected, then refer to the above mentioned SI Document Numbers
for further assistance in repairing the condition.
Parts Information
Part Number
| Description
|
12589430
| Cap, Oil Fill (Vented)
|
Parts are currently available from GMSPO.
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation
| Description
| Labor Time
|
J 7508*
| Cap, Oil Fill (Vented) - Replace
| 0.3 hr
|
*This is a unique labor operation for bulletin use only.
