Cylinder Leakage Test

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

The cylinder leakage test provides an accurate means for determining engine condition.

Cylinder leakage testing will detect:

Check the coolant level and fill as required. DO NOT install the radiator cap.
Start and operate the engine until it attains normal operating temperature.
Turn the engine OFF.
Remove the fuel injector. Refer to INJECTOR(S), FUEL, REMOVAL AND INSTALLATION .
Set the piston of the cylinder to be tested at Top Dead Center (TDC) on the compression stroke.
Install the (special tool #VM.10357, Adapter, Compression Test) into the fuel injector bore of cylinder to be tested. Install fuel injector clamp, nut, and securely tighten.
Calibrate the tester according to the manufacturer's instructions. The shop air source for testing should maintain a regulated air pressure at 552 kPa (80 psi).
Connect the leakage tester and perform the leakage test procedure on each cylinder according to the tester manufacturer's instructions.
As each cylinder is pressurized, listen for the air escaping through the EGR air flow control valve, tailpipe, and the oil filler cap opening. Check for bubbles in the pressurized coolant bottle.
All gauge pressure indications should be equal, with no more than 25% leakage.

If leakage is greater then 25%, Refer to CYLINDER LEAKAGE DIAGNOSIS CHART below.

CYLINDER LEAKAGE DIAGNOSIS CHART

CONDITION	POSSIBLE CAUSE	CORRECTION
AIR ESCAPES THROUGH THROTTLE BODY	Intake valve bent, burnt, or not seated properly.	Inspect the valve and valve seat. Reface or replace, as necessary. Inspect valve springs. Replace as necessary.
AIR ESCAPES THROUGH TAILPIPE	Exhaust valve bent, burnt, or not seated properly.	Inspect the valve and valve seat. Reface or replace, as necessary. Inspect valve springs. Replace as necessary.
AIR ESCAPES THROUGH RADIATOR	Head gasket leaking or cracked cylinder head or block.	Remove the cylinder head and inspect. Replace the defective part.
MORE THAN 50% LEAKAGE FROM ADJACENT CYLINDERS	Head gasket leaking or crack in cylinder head or block between adjacent cylinders.	Remove the cylinder head and inspect. Replace gasket, head, or block as necessary.
MORE THAN 25% LEAKAGE AND AIR ESCAPES THROUGH OIL FILLER CAP OPENING ONLY	Stuck or broken piston rings; cracked piston; worn rings and/or cylinder wall.	Inspect for broken rings or piston. Measure the ring gap and cylinder diameter, taper and out-of-round. Replace the defective part as necessary.