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Cylinder Leakage Test

Cylinder Leakage Test



Special Tools

• EN-35667-A Cylinder Head Leakdown Tester

• EN-39313 Spark Plug Port Air Adapter


For equivalent regional tools, refer to Special Tools .

Note

A leakage test may be performed in order 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 lifters

• Incorrect valve lash/adjustment

• Damaged piston

• Worn piston rings

• Worn or scored cylinder bore

• Damaged cylinder head gasket

• Cracked or damaged cylinder head

• Cracked or damaged engine block


Refer to Battery Disconnect Warning .


1. Disconnect the battery ground negative cable.

2. Remove all spark plugs. Refer to Spark Plug Replacement .

3. Rotate the crankshaft to place the piston in the cylinder being tested at top dead center (TDC) of the compression stroke.

4. Thread the EN-39313 adapter into the spark plug hole.

5. Install the EN-35667-A tester or equivalent.

6.
Note

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


Apply shop air pressure to the EN-35667-A tester and adjust according to the manufacturers instructions.

7. 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 body or air inlet hose that may indicate a worn or burnt intake valve or a broken valve spring.

• Air leakage sounds at the exhaust system tailpipe that 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 that 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.

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