Cylinder Leakage Test

WARNING: This page is about a different car, the 2002 Oldsmobile Bravada, 2002 GMC Envoy XL, 2002 GMC Envoy, and 2002 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

J 35667-A Cylinder Leakdown Tester

With the use of air pressure, a cylinder leakage test will aid in the diagnosis. The cylinder leakage test may be used in conjunction with the engine compression test, to isolate the cause of leaking cylinders.

CAUTION: Before servicing any electrical component, the ignition key must be in the OFF or LOCK position and all electrical loads must be OFF, unless instructed otherwise in these procedures. If a tool or equipment could easily come in contact with a live exposed electrical terminal, also disconnect the negative battery cable. Failure to follow these precautions may cause personal injury and/or damage to the vehicle or its components.

Remove the battery ground (negative) cable. Refer to Battery Negative Cable Disconnect/Connect Procedure in Electrical.
Remove the spark plugs. Refer to Ignition System in Engine.
Install J 35667-A.

Fig 1: Installing J 35667-A To Engine

Courtesy of GENERAL MOTORS CORP.

Measure each cylinder on the compression stroke, with the valves closed.
IMPORTANT: It may be necessary to hold the crankshaft balancer bolt, to prevent piston movement.
Apply air pressure, using J 35667-A. Refer to the manufacturer's instructions.
Record the cylinder leakage readings for each cylinder.
IMPORTANT:
- 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 requires service.
Inspect the four primary areas, to properly diagnose a leaking cylinder.
If air is heard from the intake or exhaust system, perform the following procedure:
- Remove the camshaft cover.
  - Ensure the valves are closed.
  - Inspect the cylinder head for a broken valve spring.
- Remove the cylinder head and inspect. Refer to Cylinder Head Cleaning and Inspection .
If 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 piston and connecting rod assembly. Refer to Piston, Connecting Rod, and Bearings Cleaning and Inspection .
- Inspect the engine block. Refer to Engine Block Cleaning and Inspection .
If bubbles are found in the radiator, perform the following procedure:
- Remove the cylinder head and inspect. Refer to Cylinder Head Cleaning and Inspection .
- Inspect the engine block. Refer to Engine Block Cleaning and Inspection .
Remove the J 35667-A.
Install the spark plugs. Refer to Ignition System in Engine Electrical.
Install the battery ground (negative) cable. Refer to Battery Negative Cable Disconnect/Connect Procedure in Engine Electrical.