Positive Crankcase Ventilation: Service and Repair

Crankcase Ventilation System Inspection


NOTE: Operating an engine without an effective crankcase ventilation system may damage the engine. Replace the Positive Crankcase Ventilation (PCV) valve at regular intervals. Use the correct PCV valve for the engine and equipment type. Wrong or substandard parts may damage the engine components.

Use the following procedure in order to check the function of the PCV system:
1. Start the engine.
2. Run the engine at idle.
3. Place your thumb over the end of the PCV valve (1) to check for vacuum. If there is no vacuum at the PCV valve, check for a plugged intake manifold port, PCV valve or vacuum hose. Replace or repair as necessary.
4. Turn OFF the ignition.
5. Remove the PCV valve.




6. Shake the PCV valve while listening for the rattle of the needle inside. Replace the PCV valve if the valve does not rattle.
^ Proper operation of the PCV system is dependent upon a sealed engine with a freely flowing breather tube. Build up of oil sludge or oil dilution is an indication of a leak in the PCV system or crankcase.
- Inspect that the PCV breather tube and pipe are not blocked.
- Inspect all the hoses and clamps in the PCV system for signs of damage or deterioration.
- Inspect the engine for external oil leaks.
^ Repair as necessary.
7. Install the PCV valve to the PCV hose.
8. Install the PCV valve and hose into the valve cover.