Cylinder Leakage Test

Cylinder Leakage Test

Tools Required

J 35667-A Cylinder Head Leakdown Tester





Caution: Refer to Battery Disconnect Caution in Cautions and Notices.

Important: A leakage test may be performed to measure cylinder/combustion chamber leakage. High cylinder leakage may indicate one or more of the following:

- Worn or burnt valves

- Broken valve springs

- Stuck valve lash adjuster

- Damaged piston

- Worn piston rings

- Worn or scored cylinder bore

- Damaged cylinder head gasket

- Cracked or damaged cylinder head

- Cracked or damaged engine block

Disconnect the battery ground negative cable.
- Remove the spark plugs. Refer to Spark Plug Replacement in Engine Control. Service and Repair
- Rotate the crankshaft to place the piston in the cylinder being tested at Top Dead Center (TDC) of the compression stroke.
- Install J 35667-A.

Important: It may be necessary to hold the crankshaft balancer bolt to prevent the engine from rotating.

- Apply shop air pressure to J 35667-A and adjust according to the manufacturers instructions.
- 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:

- Air leakage sounds at the throttle control module or air inlet hose may indicate a worn or burnt intake valve or a broken valve spring.
- Air leakage sounds at the exhaust system tailpipe may indicate a worn or burnt exhaust valve or a broken valve spring.
- Air leakage sounds from the crankcase, oil level indicator tube, 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.
- Air bubbles in the cooling system may indicate a damaged cylinder head or a damaged cylinder head gasket.

- Perform the leakage test on the remaining cylinders and record the values.