CYLINDER COMPRESSION TEST
High cylinder pressures can be caused by combustion of lubricating
oil in the cylinder combustion chamber.
If this occurs, allow
combustion gases to escape prior to taking compression readings by
cranking the engine with the starter for 30 seconds with the fuel
supply shut off.
4. After all 12 cylinders are checked, determine the pressure difference between high and low
a. This variation should not exceed 70 psi. (483 kPa).
b. If compression readings are below the low limit of 330 psi (2,275 kPa), the engine
motoring rpm should be checked to be sure that it is 140 to 180 rpm.
c. Compression should be checked again to confirm the previous readings before submitting
an engine for overhaul.
1. Remove gauge assembly (3) from compression adapter (2).
WP 0033 00-3