K 3500 Truck 4WD V8-393 6.5L DSL Turbo (1993)
Positive Crankcase Ventilation: Testing and Inspection
CDR Valve Operation
CDR Valve Test
The purpose of the CDR valve is to maintain 0.75-1.0 kPa (3-4 inches of water) vacuum in the crankcase. Too little vacuum will tend to force oil
leaks. Too much vacuum will pull oil into the air crossover.
The CDR valve is checked with a water manometer. The U-tube manometer indicates pressure or vacuum by the difference in the height of two
columns of fluid.
Connect one end of the manometer to the engine oil dipstick hole. The other end of the manometer is vented to atmosphere.
Install air cleaner and run engine at idle.
One inch (1") water pressure at idle to approximately 3-4 inches water vacuum at full load. Add the amount that the manometer column travels up,
