If the results of a compression test or crankcase pressure check indicate that carbon accumulation may cause the piston rings to stick in their grooves, the following procedure may be performed:
1. Bring the engine to operating temperature.
2. Disconnect the batteries to prevent the engine from cranking.
3. Remove the glow plugs from all cylinders.
4. Obtain one can of top engine cleaner (GM P/N 1050002) and squirt equal amounts of it into the eight cylinders through the glow plug holes.
5. Allow the top engine cleaner to work for at least 24 hours.
6. Move the vehicle to a well-ventilated area.
7. Connect the batteries.
8. Cover the glow plug holes with shop towels.
9. Crank the engine to expel the top engine cleaner through the glow plug holes.
10. Clean any spillage of top engine cleaner on engine and vehicle parts to prevent finish damage.
11. Install the glow plugs.
12. Start the engine and bring it to operating temperature.
13. Repeat the compression test or crankcase pressure check to verify that the piston rings are unstuck.
