Air Injection Check Valve: Testing and Inspection

Air Injection System:

1. The check valve (non-return valve) should be inspected whenever the hose is disconnected or whenever failure is suspected. A pump that had become inoperative and shown evidence of exhaust gas entry would indicate check valve failure.
2. Remove check valve. Air should pass freely when the valve is blown through from air pump side. No air should pass when the valve is blown through from the exhaust manifold side.
3. Replace a valve which does not operate properly.