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Crankcase Ventilation System Inspection/Diagnosis (1.6L LLU)

Crankcase Ventilation System Inspection/Diagnosis (1.6L LLU)

Results of Incorrect Operation

A plugged positive crankcase ventilation (PCV) orifice or hose may cause the following conditions:


Rough idle

Stalling or slow idle speed

Oil leaks

Oil in the throttle body

Sludge in the engine


Functional Check

With these systems, any blow-by in excess of the system capacity, from a badly worn engine, sustained heavy load, etc., is exhausted into the throttle body and is drawn into the engine.

Proper operation of the crankcase ventilation system depends upon a sealed engine. If oil slugging or dilution is noted and the crankcase ventilation system is functioning properly, check the engine for a possible cause. Correct any problems.

If an engine is idling rough, inspect for a clogged PCV orifice, a dirty vent filter, air cleaner element, or plugged hose. Replace as necessary. Use the following procedure:


1. Remove the PCV hose from the intake manifold and from the cylinder head cover.

2. Engine idling.

3. Place your thumb over the end of the hose in order to check for a vacuum. If there is no vacuum at the hose, inspect for the following items:

Plugged hoses

The manifold port

4. Switch off the engine.

5. Inspect the PCV orifice in the intake manifold and in the cylinder head cover for debris or blockage.