i guess you scrub it clean , start it and watch!

 

Crankcase Ventilation System Courtesy of GENERAL MOTORS CORP.

Test for vacuum at the positive crankcase ventilation (PCV) dirty air hose (2) where it connects to the vacuum orifice tube (5) in the camshaft cover. There should be manifold vacuum present at the hose (2). If there is no vacuum, inspect for a plugged hose, leaking hose or a plugged intake manifold passage.

If oil has accumulated in the air cleaner resonator (1), inspect for the following conditions:
2007 Hummer H3 2007 ENGINE Engine Mechanical - 3.7L - H3
 Plugged vacuum orifice tube (5) in the camshaft cover (top rear of head)
 Plugged, restricted or leaking PCV dirty air hose (2) (short rubber 90 elbow from top of head to intake manifold)
 Plugged or restricted intake manifold passage (3)
 Excessive crankcase pressure or blow-by, refer to Engine Compression Test

Additional items to inspect:
 Plugged or restricted vacuum tube (4) in the camshaft cover
 Plugged or restricted PCV fresh air hose (6)
 Plugged or restricted passage in the air cleaner resonator (1)
 Inspect the cam cover, the oil pan, engine front cover and other sealing areas for leaks
Results of Incorrect Operation
A plugged crankcase ventilation system may contribute to the following conditions:

A rough idle

Stalling or a slow idle speed

Oil leaks

Oil accumulation in the air cleaner resonator (1)

Sludge in the engine
A leaking hose may contribute to the following conditions:

A rough idle

Stalling

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

 

Thanks Doc, glad you posted this. I was reading horror stories of cracked cylinder heads on the i service bulletins this morning. I will troubleshoot per the GM steps this weekend.