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. Refer to the manufacturer's instructions.
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.

7. Inspect the four primary areas, to properly diagnose a leaking cylinder.
8. 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.
9. 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.
10. If bubbles are found in the radiator, perform the following procedure:
^ Remove both cylinder heads and inspect.
^ Inspect the engine block.
11. Remove the J 35667-A.
12. Install the spark plugs.
13. Install the battery ground - negative cable.