Crankcase Depression Regulator (CDR) Valve
To test CDR valve, connect one end of a water manometer to engine oil dipstick tube. Leave other end of manometer open to atmosphere. Unplug rubber vent tube from turbo inlet elbow. Install air cleaner and run engine. CDR valve specification is one in. H2 O at idle to 3-4 in. H2 O at full load. Add amount of distance water travels down one side of gauge to distance water travels up other side of gauge to obtain reading.