Oil Pressure Diagnosis and Testing (6.2L LS3)

Special Tools

• EN-21867  Pressure Gauge
• EN-21867-16  Oil Pressure Adapter

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 gauge or light.
4. Listen for a noisy valve train or a knocking noise.
5. Inspect for the following conditions:
   • Oil diluted by water or glycol antifreeze
   • Foamy oil
Fig 1: Oil Pressure Sensor
Courtesy of GENERAL MOTORS COMPANY
6. Remove the oil pressure sensor (1).
Fig 2: Engine Oil Pressure Gauge And Adapter
Courtesy of GENERAL MOTORS COMPANY
7. Install the EN-21867-16  adapter (2) and EN-21867  pressure gauge (1), or equivalent.
8. Run the engine and measure the engine oil pressure.
9. Compare the readings to Engine Mechanical Specifications (7.0L) , Engine Mechanical Specifications (6.2L LS9) , Engine Mechanical Specifications (6.2L LS3) .
10. If the engine oil pressure is below specifications, inspect the engine for 1 or more of the following conditions:
    • Oil pump worn or dirty. Refer to Oil Pump Cleaning and Inspection (6.2L LS3) , Oil Pump Cleaning and Inspection (6.2L LS9) , Oil Pump Cleaning and Inspection (LS3 with Z52 Option, LS7) .
    • Oil pump-to-engine block bolts loose. Refer to Oil Pump, Screen and Crankshaft Oil Deflector Installation (6.2L LS3) .
    • Oil pump screen loose, plugged, or damaged
    • Oil pump screen O-ring seal missing or damaged
    • Excessive debris in the oil pan and/or oil filter (possibly indicating internal engine damage).
    • Malfunctioning oil pump pressure relief valve
    • Excessive bearing clearance and/or bearing damage. Refer to Crankshaft and Bearing Cleaning and Inspection , and Camshaft and Bearings Cleaning and Inspection .
    • Cracked, porous, or restricted oil galleries
    • Oil gallery plugs missing or incorrectly installed. Refer to Engine Block Plug Installation .
    • Broken valve lifters. Repair, as necessary.
11. If the oil pressure reading on the J 21867  pressure gauge , or equivalent, is within specifications, inspect for the following conditions:
    • Plugged or incorrect oil filter and/or malfunctioning oil bypass valve. The bypass valve is now internal to the oil filter.
    • Malfunctioning oil pressure gauge or sensor. Repair, as necessary.