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Home >> Chevrolet >> 2015 >> Cruze LT, Automatic Trans >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 3 (Engine Mechanical - 2.0L (LUZ) Diesel) >> Diagnostic Information and Procedures >> Cylinder Leakage Test

Cylinder Leakage Test

WARNING: This page is about a different variant/trim than selected.
WARNING:

Unless directed otherwise, the ignition must be OFF with the key removed and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

For Vehicles equipped with OnStar® (UE1) with Back Up Battery:

The Back Up Battery is a redundant power supply to allow limited OnStar® functionality in the event of a main vehicle battery power disruption to the VCIM (OnStar® module). Do not disconnect the main vehicle battery or remove the OnStar® fuse with the ignition key in any position other than OFF. Retained accessory power should be allowed to time out or be disabled (simply opening the driver door should disable retained accessory power) before disconnecting power. Disconnecting power to the OnStar® module in any way while the ignition is On or with retained accessory power activated may cause activation of the OnStar® Back-Up Battery system and will discharge and permanently damage the back-up battery. Once the Back-Up Battery is activated it will stay on until it has completely discharged. The back-up battery is not rechargeable and once activated the back-up battery must be replaced.

NOTE:

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

  • Worn, burnt or stuck valves
  • Broken valve springs
  • Incorrect valve lash
  • Damaged valve train components
  • Damaged piston
  • Worn piston rings
  • Worn or scored cylinder bore
  • Damaged cylinder head gasket
  • Cracked or damaged cylinder head
  • Cracked or damaged engine block
  1. Disconnect the battery negative cable. Refer to Battery Negative Cable Disconnection and Connection .
  2. Remove the glow plugs.
  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 leakdown tester and the adapter.
    NOTE: It may be necessary to hold the crankshaft balancer bolt to prevent the engine from rotating.
  5. Apply shop air pressure to the tester and adjust according to the manufacturers instructions.
  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 sounds at the intake manifold tube, may indicate a worn, stuck or burnt intake valve, broken valve spring, incorrect valve lash or damaged valve train components.
    • Air leakage sounds at the exhaust system tailpipe may indicate a worn, burnt or stuck exhaust valve, broken valve spring, incorrect valve lash or damaged valve train components.
    • 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 gasket.
  7. Perform the leakage test on the remaining cylinders and record the values.
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