Check Valve Test

Operate engine until it reaches normal operating temperature. Inspect all hoses and connectors for obvious leaks and correct as necessary before checking valve operation. Disconnect air supply hose at check valve and visually inspect position of valve plate inside valve body. It should be lightly positioned against valve seat away from air distribution manifold. Insert a probe into valve connection and depress valve plate. It should freely return to original position against valve seat, when released. Leave hose disconnected and start engine. Slowly increase engine speed to 1500 RPM and watch for exhaust gas leakage at check valve. There should be no leakage. The valve may flutter or vibrate at idle speeds, but this is normal due to exhaust pulsations in manifold. If check valve does not meet the above recommended conditions, replace it.