Displacement on Demand (DoD) Oil Pressure Relief Valve Diagnosis and Testing

Tools Required

• J-21867-16  Displacement on Demand Oil Pressure Test Adapter. See Special Tools .
• J 21867  Pressure Gage
• J 42907  Oil Pressure Testing Tool. See Special Tools .

Fig 1: Installing J 21867 To The J 42907 To Measure The Engine Oil Pressure
Courtesy of GENERAL MOTORS CORP.
IMPORTANT: This test is performed to verify the operation of the oil pressure relief valve. Refer to Displacement on Demand (DoD) System Description  and Lubrication Description (Main Pressure Below 65 psi - DoD Off)  or Lubrication Description (Main Pressure Above 65 psi - DoD Off)  or Lubrication Description (Main Pressure Below 65 psi - DoD On)  or Lubrication Description (Main Pressure Above 65 psi - DoD On) .
1. Remove the oil filter and install the J 42907  . See Special Tools .
2. Install J 21867  or equivalent to the J 42907  . See Special Tools .
Fig 2: View Of Oil Pressure Sensor
Courtesy of GENERAL MOTORS CORP.
3. Remove the oil pressure sensor and install the J-21867-16  . See Special Tools .
4. Install J 21867  or equivalent to the J-21867-16  . See Special Tools .
5. Run the engine and measure the engine oil pressure while observing both gages.

   Operate the throttle as required to increase and decrease the engine oil pressure.

   • With the engine running and the lower pressure gage measuring below 448 kPa (65 psi), both gages should display the same pressure reading. If the readings are not the same and the lower gage has a higher reading, the oil pressure relief valve is stuck in the open position or the valve lifter oil manifold filter is plugged.
   • With the engine running and the lower pressure gage measuring above 448 kPa (65 psi), the upper gage should display no greater than 448 kPa (65 psi). If the reading on the upper gage is greater than 448 kPa (65 psi), the oil pressure relief valve is stuck in the closed position.
6. Repair as required.