GM Service Manual Online
For 1990-2009 cars only

Special Tools

EN-498-B Oil Pressure Gage

For equivalent regional tools, refer to Special Tools .

  1. With the vehicle on a level surface, run the vehicle for a few minutes, allow adequate drain down time, 2-3 minutes, and measure the oil level.
  2. If required, add the recommended grade engine oil and fill the crankcase until the oil level measures full on the oil level indicator.
  3. Run the engine briefly, 10-15 seconds, and verify low or no oil pressure on the vehicle gage or light.
  4. Listen for a noisy valve train or a knocking noise.
  5. Inspect for the following conditions:
  6. • Oil diluted by water or glycol antifreeze
    • Foamy oil

    Object Number: 2028064  Size: SH
  7. Remove the engine oil pressure sensor (1).

  8. Object Number: 1847973  Size: SH

    Caution: Special new tool EN 47971 must be used. Due to the special size and thread pitch of the oil filter adapter fitting ensure the proper tool is used or component damage will result.

  9. Install the EN-498-B gage to the engine oil pressure sensor thread hole and tighten to  30 N·m (23 lb ft) .
  10. Run the engine and measure the engine oil pressure.
  11. Compare the readings to Engine Mechanical Specifications .
  12. If the engine oil pressure is below specifications, inspect the engine for 1 or more of the following conditions:
  13. • Oil pump worn or dirty. Refer to Oil Pump Replacement , Oil Pump Disassemble and Oil Pump Cleaning and Inspection .
    • Oil pump-to-oil pump housing bolts loose. Refer to Oil Pump Replacement .
    • Oil pump suction pipe loose, plugged, or damaged. Refer to Oil Pump Suction Pipe and Screen Assembly Installation and clean the suction pipe.
    • Oil pump screen O-ring seal missing or damaged. Refer to Oil Pump Replacement , Oil Pump Disassemble and Oil Pump Assemble .
    • Oil pump pressure relief valve malfunction. Refer to Oil Pump Replacement , Oil Pump Disassemble and Oil Pump Assemble .
    • Engine bearing clearance out of specifications. Refer to Crankshaft and Bearing Cleaning and Inspection , Crankshaft and Bearing Installation and Piston, Connecting Rod, and Bearing Installation .
    • Cracked, porous, or restricted oil galleries.

    Caution: This engine uses a special high performance oil filter. Use of any other filter may lead to filter failure and/or severe engine damage.

  14. If the oil pressure reading on the EN-498-B gage , or equivalent, is within specifications, inspect for the following conditions:
  15. • Plugged or incorrect oil filter and/or malfunctioning oil bypass valve. Repair, as necessary.
    • Malfunctioning EN-498-B gage or sensor. Repair, as necessary.