Cylinder Leakage Test

Cylinder Leakage Test

Tools Required
^ J35667-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.

1. Remove the battery ground - negative cable.

Caution: Refer to Battery Disconnect Caution in Service Precautions.

2. Remove the spark plugs.
3. Install the J35667-A.





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

5. Apply air pressure, using the J35667-A. Refer to the manufacturer's instructions.

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

6. Record the cylinder leakage readings for each cylinder.

7. Inspect the four primary areas, to properly diagnose a leaking 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.

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 J35667-A.
12. Install the spark plugs.
13. Install the battery ground - negative cable.