Component Tests and General Diagnostics

TOOL REQUIRED
^ J 35667-A Cylinder Leakdown Tester

NOTE: With the use of air pressure, a leak test will aid in diagnosing cylinder leakage. If necessary, the leak test may be used in conjunction with the engine compression test, in order to help isolate the cause of leaking cylinders.

1. Remove the negative battery cable.
2. Remove the spark plug.
3. Install Cylinder Leakdown Tester tool.
4. Measure the cylinder on the compression stroke, with both valves closed.

NOTE: It may be necessary to hold the crankshaft balancer bolt/screw, in order to prevent piston movement.

5. Apply air pressure, using the Cylinder Leakdown Tester.
6. Repeat the leak test for each cylinder.
7. Record the leakage readings for all of the cylinders.
^ Normal cylinder leakage is from 12 to 18 percent.
^ Make a note of any cylinder with more leakage than the other cylinders.
^ Any cylinder with 30 percent leakage or more is problematic.
8. Inspect the four primary areas, in order to properly diagnose a leaking cylinder.
9. If escaping air is heard from the intake system at the throttle body, perform the following procedure:
^ Remove the rocker cover on the suspect cylinder.
^ Ensure that both valves are closed.
^ Inspect the intake system for a broken valve spring.
^ Inspect the intake system for a burnt valve face or valve seat.
10. If escaping air can be heard from the exhaust system at the tailpipe, perform the following procedure:
^ Remove the rocker cover on the suspect cylinder.
^ Ensure that both valves are closed.
^ Inspect the exhaust system for a broken valve spring.
^ Inspect the exhaust system for a burnt valve face or valve seat.
11. If escaping air is heard from the crankcase system at the crankcase (oil filler tube), perform the following procedure:
^ Remove the piston from the suspect cylinder.
^ Inspect the crankcase system for missing or damaged piston rings.
^ Inspect the cylinder bore diameter and finish.
12. If escaping air is causing bubbles in the cooling system radiator, perform the following procedure:
^ Remove both cylinder heads and inspect for damaged cylinder head gaskets.
^ Inspect the cylinder block.
^ Inspect the cylinder heads.
13. Remove the Cylinder Leakdown Tester.
14. Install the spark plug.
15. Install the negative battery cable.