LaCrosse V6-3.8L VIN 2 (2005)
Compression Check: Testing and Inspection
Engine Compression Test
Tools Required
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J38722 Compression Tester
A compression pressure test of the engine cylinders determines the condition of the rings, the valves, and the head gasket.
1. Run the engine until it reaches normal operating temperature. The battery must be at or near full charge.
2. Turn the engine OFF.
3. Disable the ignition.
Important: Remove the Powertrain Control Module (PCM) and the ignition fuses from the I/P fuse block.
4. Disable the fuel systems.
5. Remove the spark plugs from all the cylinders.
6. Remove the air duct from the throttle body.
7. Block the throttle plate in the open position.
8. Measure the engine compression, using the following procedure:
1. Firmly install J38722 to the spark plug hole.
2. Have an assistant crank the engine through at least four compression strokes in the testing cylinder.
3. Check and record the readings on J38722 at each stroke.
4. Disconnect J38722.
5. Repeat the compression test for each cylinder.
9. Record the compression readings from all of the cylinders.
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The lowest reading should not be less than 70 percent of the highest reading.
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No cylinder reading should be less than 689 kPa (100 psi).
10. The following are examples of the possible measurements:
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When the compression measurement is normal, the compression builds up quickly and evenly to the specified compression on each cylinder.
