C 3500 HD Truck 2WD V8-8.1L VIN G (2002)
Engine Oil Pressure: Testing and Inspection
Oil Pressure Diagnosis and Testing
1. With the vehicle on a level surface, allow adequate drain down time, 2-3 minutes, and measure for a low engine oil level.
Add the recommended grade engine oil GM P/N United States 12345610, GM P/N Canada 993193, or equivalent, and fill the crankcase until the
oil level measures FULL on the oil level indicator.
2. Operate the engine and verify low or no oil pressure on the vehicle oil pressure gage or oil indicator light.
Listen for a noisy valve train or knocking noise.
3. Inspect for the following:
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Engine oil diluted by moisture or unburned fuel mixtures
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Improper engine oil viscosity for the expected temperature
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Incorrect or faulty oil pressure gage sensor
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Incorrect or faulty oil pressure gage
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Plugged oil filter
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Malfunctioning oil filter bypass valve
4. Remove the oil pressure gage sensor or another engine block oil Gallery plug.
5. Install an oil pressure gage and measure the engine oil pressure.
6. If the engine oil pressure is below specifications, inspect the engine for one or more of the following:
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Oil pump worn or dirty
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Malfunctioning oil pump pressure relief valve
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Oil pump screen loose, plugged, or damaged
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Excessive bearing clearance
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Cracked, porous or restricted oil galleries
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Engine block oil gallery plugs missing or incorrectly installed
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Broken valve lifters
