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.

1. Disconnect the battery ground negative cable.

Caution:
Refer to Battery Disconnect Caution in Service Precautions.

2. Remove the spark plugs.
3. Rotate the crankshaft to place the piston in the cylinder being tested at top dead center (TDC) of the compression stroke, with both valves closed.
4. Install the J 35667-A.

5. Apply shop air pressure to the J 35667-A and adjust according to the manufacturer instructions.

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

6. Record the cylinder leakage value. Cylinder leakage that exceeds 25 percent is considered excessive and may require component service. In excessive leakage situations, inspect for the following conditions:

Important:
Perform the leakage test on all cylinders and record the values before doing any repairs.

1. Air leakage from the intake or exhaust system may indicate a worn or burnt valve or a broken valve spring.
1. Remove the valve rocker arm cover of the suspect cylinder head.
2. Ensure that both valves are closed.
3. Inspect the cylinder head for a broken valve spring.
4. Remove and inspect the suspect cylinder head.
2. Air leakage from the crankcase, oil level indicator, or oil fill tube may indicate worn piston rings, a damaged piston, a worn or scored cylinder bore, a damaged engine block or a damaged cylinder head.
1. Remove the piston from the suspect cylinder.
2. Inspect the piston and connecting rod assembly.
3. Inspect the engine block.
4. Inspect the cylinder head.
3. Air bubbles in the cooling system may indicate a damaged cylinder head or a damaged cylinder head gasket.
1. Remove both cylinder heads.
2. Inspect both cylinder heads.
3. Inspect the engine block.
7. Remove the J 35667-A.
8. Install the spark plugs.