DEFINITION: Low or no engine oil pressure indicates a potentially serious condition with all of the engine mechanical components. Once the cause of the low or no oil pressure condition has been identified, repair all collateral damage to the engine mechanical components as well as the initial cause of the condition.

Check engine oil level. Use only the GM service parts brand and recommended grade of engine oil specified for the vehicle.

Is the engine oil level between ADD and FULL on the oil level indicator?

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Go to Step 2

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1. Operate vehicle until engine reaches normal operating temperature. Refer to Engine Mechanical Specifications in Engine Unit Repair - 6.5 L.
2. Park vehicle on a level surface.
3. Wait, 15 minutes.
4. Check engine oil level. Use only the GM service parts brand and recommended grade of engine oil specified for the vehicle.

Is the engine oil level between ADD and FULL on the oil level indicator?

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Go to Step 3

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Operate the engine and measure the engine oil pressure with the vehicle gage or light. Refer to Engine Mechanical Specifications in Engine Unit Repair - 6.5 L.

Is engine oil pressure within specification?

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System OK

Go to Step 4

1. Remove the oil pressure sender or engine block oil gallery plug.
2. Install a mechanical oil pressure gage.
3. Operate the engine and measure the engine oil pressure with the mechanical oil pressure gage. Refer to Engine Mechanical Specifications in Engine Unit Repair - 6.5 L.

Is engine oil pressure within specification?

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System OK

Go to Step 5

Change the engine oil and filter.

Operate the engine and measure the engine oil pressure with the mechanical oil pressure gage. Refer to Engine Mechanical Specifications in Engine Unit Repair - 6.5 L.

Is engine oil pressure within specification?

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System OK

Go to Step 6

1. Inspect the engine for mechanical damage. Special interest should be shown to the following areas:

•	Twisted oil cooler lines

•	Malfunctioning oil bypass valve

•	Oil pump worn or dirty

•	Oil pump-to-engine block bolts loose

•	Oil pump screen loose, plugged, or damaged

•	Oil pump screen O-ring seal missing or damaged

•	Malfunctioning oil pump pressure regulator valve

•	Excessive bearing clearance

•	Cracked, porous or restricted oil galleries

•	Oil gallery plugs missing or incorrectly installed

•	Damaged or missing oil spray cooling nozzles

•	Broken valve lifters

2. Inspect the engine for customer modifications.

Is there mechanical damage, or customer modifications to the engine?

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Go to Step 7

Go to Step 1

Repair or replace all damaged or modified components.

Is the repair complete?

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Go to Step 1

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