Cylinder Leakage Test

Special Tools

• EN-35667 - A  Cylinder Head Leakdown Tester
• EN-51749  Compression Gauge Tester Kit

Equivalent regional tools: Special Tools

Procedure 

A leakage test is 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

WARNING:

Refer to Battery Disconnect Warning .

1. Disconnect the battery ground negative cable.
2. Remove the spark plugs. Gas Engine Ignition Spark Plug Replacement
CAUTION:

Only turn the engine in a CLOCKWISE direction as viewed from the crankshaft balancer. Counterclockwise rotation may result in the timing chain jumping a tooth, causing poor running, DTCs, or severe engine damage.

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-51749  adapter into the spark plug hole.
5. Install the EN-35667 - A  tester or equivalent.
NOTE:

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

6. 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.