Cylinder Leakage Test

Testing Procedure

^ Tools Required
- J35667-A Cylinder 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.
1. Disconnect the negative battery cable. Refer to Battery Disconnect Caution in Service Precautions.
2. Remove the spark plugs. Refer to Spark Plug Replacement in Powertrain Management.
3. Install the J35667-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 J35667-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. Refer to Cylinder Head Clean and Inspect.

9. If air is heard from the crankcase system at the crankcase (oil filler tube), perform the following procedure:
9.1. Remove the piston from the suspect cylinder.
9.2. Inspect the piston and connecting rod assembly. Refer to Piston, Connecting Rod, and Bearings Clean and Inspect.
9.3. Inspect the engine block. Refer to Engine Block Clean and Inspect.
10. If bubbles are found in the radiator, perform the following procedure:
^ Remove and inspect both cylinder heads. Refer to Cylinder Head Clean and Inspect.
^ Inspect the engine block. Refer to Engine Block Clean and Inspect.

11. Remove the J35667-A.
12. Install the spark plugs. Refer to Ignition System Spark Plug Replacement in Powertrain Management.
13. Connect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure.