Engine Compression Test
Special Tools
| • |
EN-26999
Compression Gauge |
| • |
EN-47603
Compression Gauge Adapter |
For equivalent regional tools, refer to
Special Tools .
| 1. |
Ensure that the vehicle
batteries are in good condition, and fully charged. |
| 2. |
Operate the vehicle until the
engine is at normal operating temperature. |
| 4. |
Disconnect the crankshaft
position sensor. |
| 5. |
Disconnect the glow plug nut;
remove all 4 glow plugs. All 4 glow plugs must be removed from the
engine during each cylinder test to obtain valid test
results. |
| 6. |
Prior to taking a compression
reading, verify the cranking speed is greater than 140 RPM. If the
cranking speed is below 140 RPM, repair the slow cranking speed
condition before continuing with the compression test. Refer to
Engine Cranks Slowly . |
| 7. |
Install the EN-47603
adapter in the glow plug hole for the cylinder that is being
checked. |
|
Caution: Do
not add oil to any cylinder during a compression test as extensive
engine damage may result. |
| 8. |
Connect the EN-26999
gauge to the EN-47603 adapter . |
| 9. |
Using the vehicle starter
motor, rotate or crank the engine for 6 compression strokes, puffs,
for the cylinder being tested. |
| 10. |
Observe the EN-26999
gauge and note the reading as the compression test is being
performed. A normal cylinder reading will be indicated if
compression builds up quickly and evenly to the specified level. An
abnormal reading will be indicated if compression is low on the
first compression stroke, starts increasing on the following
compression strokes but does not reach the specified level.
|
| 11. |
Record the compression reading
for the cylinder just tested. |
| 12. |
Disconnect the
EN-26999 gauge from the EN-47603
adapter and remove the adapter from the glow plug hole.
|
| 13. |
Repeat steps 8-13 for all
remaining cylinders. All 4 cylinders must be tested to obtain valid
test results. Record the readings. |
| 14. |
The minimum compression in any
one cylinder is 2600 kPa (377 psi) . There should
not be more than 260 kPa (38 psi) difference
between a suspect cylinder and the average compression of all 4
cylinders. |
| |
• |
Normal-Compression builds up
quickly and evenly to the specified compression for each
cylinder. |
| |
• |
Piston rings
leaking-Compression is low on the first stroke. Compression builds
up with the following strokes but does not reach normal.
|
| |
• |
Valves leaking-Compression is
low on the first stroke. Compression usually does not build up on
the following strokes. |
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