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. 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 .
1. Disconnect the negative battery cable.
2. Remove the spark plugs. Refer to Spark Plug Replacement .
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 12-18 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 Cleaning and Inspection (Overhaul) .

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. Refer to Piston, Connecting Rod, and Bearing Cleaning and Inspection (Overhaul) .
3. Inspect the engine block. Refer to Engine Block Cleaning and Inspection (Overhaul) .

10. If bubbles are found in the radiator, perform the following procedure:

* Remove and inspect both cylinder heads. Refer to Cylinder Head Cleaning and Inspection (Overhaul) .
* Inspect the engine block. Refer to Engine Block Cleaning and Inspection (Overhaul) .

11. Remove the J 35667-A .
12. Install the spark plugs. Refer to Spark Plug Replacement .
13. Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection (RPO LS4) Battery Negative Cable Disconnection and Connection (RPOs LZE/LZ4/LZ8) .