After overhaul, the engine should be tested before installation in the vehicle. If a suitable test stand is not available, the following procedure can be used after the engine is installed in the vehicle.

1. Fill the crankcase with the proper quantity and grade of engine oil.
2. Add engine oil supplement GM P/N 12345795 or equivalent.

Refer to Sealers, Adhesives, and Lubricants .

3. Fill the cooling system with the proper quantity and grade of coolant.
4. Disable the ignition system.
5. Crank the engine several times. Listen for any unusual noises or evidence that parts are binding.
6. Start the engine and listen for unusual noises.
7. Check the vehicle oil pressure gauge or light and confirm that the engine has acceptable oil pressure.

If necessary, install an oil pressure gauge and measure the engine oil pressure.

Refer to Oil Pressure Diagnosis and Testing and Engine Mechanical Specifications .

8. Run the engine speed at about 1000 RPM until the engine has reached normal operating temperature.
9. Listen for sticking lifters and other unusual noises.
10. Inspect for fuel, oil and/or coolant leaks while the engine is running.
11. Perform a final inspection for the proper engine oil and coolant levels.