GM Service Manual Online
For 1990-2009 cars only

Object Number: 1226040  Size: SH

A crankcase ventilation system is used in order to provide a more complete scavenging of crankcase vapors. The air cleaner supplies fresh air (1) through a filter to the crankcase.


Object Number: 637635  Size: SH

The crankcase mixes the fresh air with blow-by gases. This mixture then passes through an orifice in the cylinder head gasket and to a pipe located in the intake manifold.

The crankcase ventilation system has no serviceable components so no maintenance of the system is required.

Symptom

Correction

External Oil Leak

Inspect for any of the following conditions:

    • Restricted or kinked PCV hose or engine vent hose
    • Damaged, incorrect, or incorrectly installed PCV hose
    • Excessive crankcase pressure

Rough Idle

Inspect for any of the following conditions:

    • Restricted or kinked PCV hose or engine vent hose
    • Leaking (damaged) PCV hose
    • Vacuum hoses worn or not properly installed

Stalling or Slow Idle Speed

Inspect for any of the following conditions:

    • Restricted or kinked engine vent hose
    • Leaking (damaged) PCV hose

High Idle Speed

Inspect for a leaking (damaged) PCV hose

Sludge In the Engine

Inspect for restricted or kinked PCV hose or engine vent hose