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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 62 (Engine Mechanical) >> Diagnostic Information and Procedures >> Cylinder Leakage Test >> Tools Required

Tools Required

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J 35667-A  Cylinder Head Leakdown Tester, or equivalent. See Special Tools .

IMPORTANT: 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 conditions:
  • Worn or burnt valves
  • Broken valve springs
  • Stuck valve lifters
  • Incorrect valve lash
  • Damaged piston
  • Worn piston rings
  • Worn or scored cylinder bore
  • Damaged cylinder head gasket
  • Cracked or damaged cylinder head
  • Cracked or damaged engine block
    CAUTION: Refer to Battery Disconnect Caution in Cautions and Notices.
  1. Disconnect the battery ground negative cable.
  2. Remove the spark plugs. Refer to Spark Plug Replacement in Engine Controls - 6.0L.
  3. Rotate the crankshaft to place the piston in the cylinder being tested at top dead center (TDC) of the compression stroke.
  4. Install the J 35667-A  , or equivalent. See Special Tools .
    5. IMPORTANT: It may be necessary to hold the crankshaft balancer bolt to prevent the crankshaft from rotating.
  5. Apply shop air pressure to the J 35667-A  and adjust according to the manufacturers instructions. See Special Tools .
  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:
    • Air leakage noise at the throttle body or air inlet hose that may indicate a worn or burnt intake valve or a broken valve spring.
    • Air leakage noise at the exhaust system tailpipe that may indicate a worn or burnt exhaust valve or a broken valve spring.
    • Air leakage noise 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.
  7. Perform the leakage test on the remaining cylinders and record the values.
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