System Checking
If sludging of PCV valve occurs it will not operate and valve may be closed. This will cause high crankcase pressure at highway speeds. This pressure can cause engine to blow out oil through engine seals and gaskets. A plugged system will cause a rough idle. Check for rough idle due to defective PCV valve as follows: Connect tachometer to engine and start engine and adjust idle. Clamp off hose from PCV valve to carburetor base. If system is working properly, engine RPM will change 50 to 60 RPM. You should be able to hear valve click shut when clamping off hose and releasing it several times. There will be no change in engine RPM if PCV valve or hoses are sludged up or restricted.