Tools Required

1. Ensure that the vehicle's batteries are in good condition, and fully charged.
2. Operate the vehicle until the engine is at normal operating temperature.
3. Remove the ECM 1 fuse in the underhood fuse block.
4. Check the engine cranking speed. The minimum cranking speed specification must be met to obtain valid test results. Refer to Engine Cranking Speed Test .
5. Using the J 41515-A , remove all eight glow plugs. All eight glow plugs must be removed from the engine during each cylinder test to obtain valid test results.




Notice: Do not add oil to any cylinder during a compression test as extensive engine damage may result.

6. Install the J 26999-10 , or the J 26999-30 , as appropriate, in the glow plug hole for the cylinder that is being checked.
7. Connect the J 26999 to the J 26999-10 , or theJ 26999-30 , as appropriate.
8. Using the vehicle's starter motor, rotate, crank, the engine for ten compression strokes, puffs, for the cylinder being tested. If the engine rotates for more than ten compression strokes, re-test the cylinder.

•	Normal: The compression builds up quickly and evenly to the specified compression.

•	Leaking: The compression is low on the first compression stroke. The compression builds up on the following compression strokes but does not reach the specified compression.

9. Record the compression reading.
10. Disconnect the J 26999 from the J 26999-10 .
11. Remove the J 26999-30 .
12. Repeat steps 5 through 11 for all remaining cylinders. All eight cylinders must be tested to obtain valid test results.
13. Check the compression readings.
14. If one or more cylinders fails to meet the minimum specified compression, repair or replace damaged or malfunctioning components and retest.
15. Using the J 41515-A , install all eight glow plugs.
16. Install the ECM 1 fuse.