Positive Crankcase Ventilation: Testing and Inspection

Fig. 14 Positive Crankcase Ventilation System:

Visually inspect the rubber hoses for cracks, restrictions, damage and oil saturation. To ensure correct operation of PCV system, use low pressure air (blow it through all PCV hoses) to check for clogging and restrictions.
If necessary, check the inside of the valve cover where the PCV fitting inserts. There may be some sludge build-up that would interfere with the crankcase vapor return. Should this area become clogged, high crankcase pressure would result. This can cause abnormal oil leakage from some or all engine gaskets and seals. Replace valve cover or clean the affected area and check for good vapor flow.