Positive Crankcase Ventilation (PCV)
Ensure crankcase ventilation hoses and connections are not clogged and no leaks exist. Start engine. With engine at idle, pinch and release PCV hose. Clicking noise should occur. If no clicking noise occurs, ensure manifold vacuum is present. If manifold vacuum is present, replace PCV valve and recheck. If manifold vacuum is not present, check for restricted vacuum port or PCV hose.