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 Hinge Pillar Body Sectioning
Removal Procedure Warning: Refer to Approved Equipment for Collision Repair Warning. Warning: Refer to Collision Sectioning Warning. Warning: Refer to Glass and Sheet Metal Handling Warning. Disable the SIR system. Refer to SIR Disabling a ...

Steering Angle Sensor Centering
The steering angle sensor does not require centering often. Centering of the steering angle sensor might be required after certain service procedures are performed. Some of these procedures are as follows: Wheel alignment Steering gear replacement Steering column replacement Collision ...

Battery Negative Cable Replacement
Battery Negative Cable Replacement Callout Component Name Preliminary Procedures Disconnect the battery current sensor connector. Remove the battery tray. Refer to Battery Tray Replacement. 1 Bo ...

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