Tools Required

1. Ensure that the vehicle's batteries are in good condition, and fully charged. Refer to Battery Inspection/Test in Engine Electrical.
2. Operate the vehicle until the engine is at normal operating temperature.
3. Check the engine cranking speed. The minimum cranking speed specification must be met to obtain valid test results. Refer to Engine Cranking Speed Test .
4. Remove the fuel solenoid driver fuse.
5. Using the J 41515-A Glow Plug Socket, 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 Compression Gauge Adapter, or the J 26999-30 Compression Gauge Adapter, as appropriate, in the glow plug hole for the cylinder that is being checked.
7. Connect the J 26999 Compression Gauge to the Compression Gauge Adapter.
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 minimum 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 minimum specified compression.

9. Record the compression reading.
10. Disconnect the Compression Gauge from the Compression Gauge Adapter.
11. Remove the Compression Gauge Adapter.
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. Refer to Engine Mechanical Specifications .
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 Glow Plug Socket, install all eight glow plugs.
16. Install the fuel solenoid driver fuse.