Cylinder Leakage Test

Cylinder Leakage Test

Tools Required

J 35667-A Cylinder Head Leakdown Tester

With the use of air pressure, a cylinder leakage test will aid in the diagnosis. The cylinder leakage test may be used in conjunction with the engine compression test, to isolate the cause of leaking cylinders.

Caution: Refer to Battery Disconnect Caution in Service Precautions.

1. Remove the battery ground - negative cable.
2. Remove the spark plugs.
3. Install the J 35667-A.




4. Measure each cylinder on the compression stroke, with both valves closed.

Important: It may be necessary to hold the crankshaft balancer bolt, to prevent piston movement.

5. Apply air pressure, using the J 35667-A.
6. Record the cylinder leakage readings for each cylinder.

Important:
^ Normal cylinder leakage is from 12-18 percent.

^ Make a note of any cylinder with more leakage than the other cylinders.

^ Any cylinder with 30 percent leakage or more requires service.

Inspect the four primary areas, to properly diagnose a leaking cylinder.
7. If air is heard from the intake or exhaust system, perform the following procedure:
* Remove the valve rocker arm cover of the suspect cylinder head.
- Ensure that both valves are closed.
- Inspect the cylinder head for a broken valve spring.
* Remove the suspect cylinder head and inspect.
8. If air is heard from the crankcase system at the crankcase, oil filler tube, perform the following procedure:
* Remove the piston from the suspect cylinder.
* Inspect the piston and connecting rod assembly
* Inspect the engine block.
9. If bubbles are found in the radiator, perform the following procedure:
* Remove both cylinder heads and inspect.
* Inspect the engine block.
10. Remove the J 35667-A.
11. Install the spark plugs.
12. Install the battery ground - negative cable.