INSER 0.26 mm(.010 in.) oversize 4S8897 - Caterpillar

Disconnect the ignition coil wire harness connector at the front of the engine on the left cylinder back and the rear right cylinder bank.
Disconnect the fuel injector electrical harness connector at the rear of the intake manifold.
Remove all the spark plugs.
Block the throttle plate wide open.
Charge the battery if the battery is not fully charged.
Start with the compression gauge at zero. Crank the engine through the four compression strokes.
Make the compression check the same for each cylinder and record the readings.Note: The minimum compression is any one cylinder should not be less than 70 percent of the cylinder. No cylinder should read less than 690 kPa (100 psi).
If one of the cylinders has low compression, inject approximately 15 mL (0.50 oz) of engine oil into the combustion chamber through the spark plug hole.
Normal - Compression builds up quickly and evenly to the specified compression for each cylinder.
Piston Rings Leaking - Compression is low on the first stroke. Then compression builds up with the following strokes, but does not reach normal levels. Compression improves considerably after adding oil.
Valves Leaking - Compression is low on the first stroke. Compression usually does not build up on the following strokes. Compression does not improve much when adding oil.Note: If two adjacent cylinders have lower than normal compression, and injecting oil into the cylinders does not increase the compression, the cause may be a head gasket leaking between the two cylinders.