Cylinder Leakage Test

Cylinder Leakage Test

Testing Procedure

^ Tools Required
- J 35667-A Cylinder Head Leakdown Tester

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

Caution: Refer to Battery Disconnect Caution in Service Precautions.

1. Disconnect the negative battery 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: Hold the crankshaft balancer bolt in order 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 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 4 primary areas in order 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 and inspect the suspect cylinder head.
9. If air is heard from the crankcase system at the crankcase oil filler tube, perform the following procedure:
= 1. Remove the piston from the suspect cylinder.
= 2. Inspect the piston and connecting rod assembly.
= 3. Inspect the engine block.
10. If bubbles are found in the radiator, perform the following procedure:
^ Remove and inspect both cylinder heads.
^ Inspect the engine block.
11. Remove the J 35667-A.
12. Install the spark plugs.
13. Connect the negative battery cable. Refer to Battery Disconnect Caution in Service Precautions.