Crankcase Depression Regulator Valve (6.5L)

The purpose of Crankcase Depression Regulator (CDR) valve is to maintain 0-4 in. H₂ O (0-0.996 kPa) vacuum in crankcase at all engine speeds, assuming that piston/ring combustion blow-by is not excessive (less than 4 cm). Too little vacuum will tend to force oil leaks. CDR valve is checked with a water manometer. A "U" tube manometer indicates pressure or vacuum by difference in height of 2 columns of fluid. If crankcase vacuum is more than 4 in. H₂ O (0.996 kPa), dirt or dust can be pulled into crankcase cavity through front/rear crankcase seal, etc. and contaminate oil. If crankcase pressure is positive, engine oil leaks are likely to occur around engine seals and gaskets.

1. Connect one end of manometer to engine oil dipstick hole. The other end of manometer is vented to atmosphere.
2. Unplug rubber vent tube from turbo inlet elbow.
3. Run engine through a no-load speed range (gear selector in PARK) and observe manometer readings. If manometer reading is 4 in. H₂ O (0.996 kPa) or less positive pressure, reconnect CDR system and proceed to next step. If manometer reading is higher than 4 in. H₂ O (0.996 kPa) positive pressure, this indicates that there is an internal engine problem.
4. Install air cleaner.
5. Start engine and observe manometer (vacuum) reading. Manometer reading should be approximately 0-1 in. H₂ O (0.249 kPa) at idle to approximately 3-5 in. H₂ O (0.747-1.245 kPa) at 2000 RPM. Add amount that manometer column travels up, to amount that column travels down, in order to obtain total water pressure (vacuum).