If an engine is idling rough, check for a clogged PCV valve or plugged hose. Replace as required. Use the following procedure:

1. Remove the PCV valve.
2. Run the engine at idle.
3. Place your thumb over the end of the valve to verify a vacuum. If there is no vacuum at valve, inspect for one or more of the following conditions:

•	Plugged hoses

•	Plugged manifold port

•	Plugged PCV valve

4. Replace plugged or deteriorated hoses.
5. Turn OFF the engine and remove PCV valve. Shake valve and listen for the rattle of needle inside the valve. If valve does not rattle, replace valve.

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

Proper operation of the PCV system is dependent upon a sealed engine. If oil sludging or dilution is noted, and the PCV system is functioning properly, perform the following procedures:

1. Inspect the engine for one or more of the following conditons:

•	The oil cap is missing

•	The dipstick is missing

•	History of infrequent oil changes exists

•	Evidence of an internal coolant leak exists

2. Correct the problematic conditions to ensure that the system will function properly.