Positive Crankcase Ventilation: Service and Repair

To check vent valve, remove it from engine and alternately apply air to both sides of valve. Air should flow freely when applied from the crankcase end of valve. Air should not flow when applied from the intake manifold side.
Check all hoses for deterioration, obstructions, wear or damage. Replace hoses as necessary. Ensure that hoses fit tight.
On 5M-GE and 7M-GE and 7M-GTE engines, disconnect the hoses and remove the orifices. Clean with solvent and blow clear with compressed air.