When performing cylinder leakage tests, the following tips might be helpful:
• Remove all spark plugs to allow easier rotation of the engine. (If this test is done
after a compression test, the plugs should already be out).
• Perform the leakage test on all cylinders, not just the problem cylinder. This would
indicate any other problems which can be rectified. This eliminates any repeat
repairs and wasted diagnostic time.
• Perform the leakage test in cylinder firing order starting with cylinder #1. It takes two
revolutions of the engine to complete the leakage test. Start at cylinder #1 and
rotate the engine to the next cylinder in the firing order. Divide the number of cylinders
into 720, the result is the number of degrees that each cylinder fires.
if you divide a 6 cylinder into 720, this equals 120 degrees. If you start at cylinder
1 and rotate the engine 120 degrees in the direction of rotation, you can check
the next cylinder in the firing order. This process eliminates the need to rotate the
engine an excessive amount.
The graphic depicts an engine with a firing order of: 1-5-3-6-2-4
If leakage is found monitoring area of loss will indicate failed component.
For example, excessive leakage on gauge and:
heard from exhaust would indicate a failed exhaust valve.
heard from intake manifold would indicate failed intake valve.
found in cooling system would indicate failed head gasket or cracked cylinder head.
heard in dipstick tube would indicate faulty piston rings.