Chevrolet Sonic Repair Manual: Crankcase Ventilation System Inspection/Diagnosis
- Results of Incorrect Operation
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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
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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 required. Use the following procedure:
- Remove the PCV hose from the cylinder head cover.
- Operate the engine at idle.
- 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
- Turn OFF the engine.
- Inspect the PCV orifice in the cylinder head cover for debris or blockage.
PCV
...
Positive Crankcase Ventilation Hose/Pipe/Tube Replacement
Removal Procedure
Remove the air cleaner outlet duct. Refer to Air Cleaner Outlet Duct
Replacement.
Open the 2 positive crankcase ventilation pipe retainer clips ...
Other materials:
Driving on Wet Roads
Rain and wet roads can reduce vehicle traction and affect your ability to stop
and accelerate. Always drive slower in these types of driving conditions and avoid
driving through large puddles and deep‐standing or flowing water.
Warning
Wet brakes can cause crashes. They might not work as ...
Outside Rearview Mirror Remote Control Switch Replacement
Outside Rearview Mirror Remote Control Switch Replacement
Callout
Component Name
Preliminary Procedure
Remove the front side door widow switch bezel. Refer to Front Side Door
Window Switch Bezel Replacement.
...
Transmission Fluid Cooler Flushing and Flow Test
GM studies indicate that plugged or restricted transmission oil coolers and pipes
cause insufficient transmission lubrication and elevated operating temperatures
which can lead to premature transmission failure. Many repeat repair cases could
have been prevented by following published procedur ...
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