Cylinder Leakage Test

Cylinder Leakage Test

Tools Required
- J 35667-A Cylinder 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.
Vehicle Damage Warnings


1. Remove the battery ground (negative) cable.
2. Remove the spark plugs.







3. Install J 35667-A.
4. Measure each cylinder on the compression stroke, with the valves closed.

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

5. Apply air pressure, using 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 to 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 camshaft cover.
- Ensure the valves are closed.
- Inspect the cylinder head for a broken valve spring.

* Remove the 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 the cylinder head and inspect.
- Inspect the engine block.

11. Remove the J 35667-A.
12. Install the spark plugs.
13. Install the battery ground (negative) cable.