Tools Required
J 35667-A Cylinder
Head Leakdown Tester
With the use of air pressure, a cylinder leakage test will aid in the
diagnosis. Use the cylinder leakage test in conjunction with the engine
compression test in order to isolate the cause of leaking cylinders.
Caution: Refer to Battery Disconnect Caution in the Preface section.
- Disconnect the battery ground negative cable.
- Remove the spark plugs. Refer to
Spark Plug Replacement
in Engine Controls - 4.3L.
- Rotate the crankshaft to place the piston in the cylinder being
tested at top dead center (TDC) of the compression stroke, with both valves
closed.
- Install the J 35667-A
.
Important: It may be necessary to hold the crankshaft balancer bolt to prevent
piston movement.
- Apply shop air pressure to the J 35667-A
and adjust according to the manufacturer instructions.
Important: Perform the leakage test on all cylinders and record the values before
doing any repairs.
- 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:
6.1. | Air leakage from the intake or exhaust system may indicate a worn
or burnt valve or a broken valve spring. |
6.1.2. | Ensure that both valves are closed. |
6.1.3. | Inspect the cylinder head for a broken valve spring. |
6.2. | Air leakage from the crankcase, oil level indicator, 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. |
6.3. | Air bubbles in the cooling system may indicate a damaged cylinder
head or a damaged cylinder head gasket. |
- Remove the J 35667-A
.
- Install the spark plugs. Refer to
Spark Plug Replacement
.
- Connect the battery ground negative cable.