D 350 Pickup V8-360 5.9L VIN W (1984)
Air Injection Check Valve: Description and Operation
A check valve, located in the injection tube assemblies leading to the exhaust manifolds on 4, V6 and V8 cylinder engines and to the cylinder head and
exhaust pipe on In-Line 6 cylinder engines, incorporates a one-way diaphragm to prevent hot exhaust gases from backing up into the hose and pump. In
the event of drive belt failure, air hose ruptures, or abnormally high exhaust system pressure, the check valve will protect the system.