Chevrolet Sonic Repair Manual: Crankcase Ventilation System Inspection/Diagnosis

Chevrolet Sonic Repair Manual / Powertrain / Engine / Emissions / PCV / Crankcase Ventilation System Inspection/Diagnosis

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 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

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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:

Front Fog Lamp Bulb Replacement
Front Fog Lamp Bulb Replacement Callout Component Name Preliminary Procedure Remove either the left front or right front wheelhouse liner. Refer to Front Wheelhouse Liner Replacement. Disconnect the electrical connector t ...

Brake Pedal Assembly Replacement
Removal Procedure Remove the battery tray. Refer to Battery Tray Replacement. Remove the power vacuum brake booster bolts (1). Remove the brake pedal assembly upper nuts (1) Remove the brake pedal assembly lower nuts (1) Remo ...

Front Wheel Drive Intermediate Shaft Replacement
Front Wheel Drive Intermediate Shaft Replacement Callout Component Name Preliminary Procedure Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle. Remove the wheel drive shaft assembly from the vehicle ...

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