CYLINDER COMPRESSION CHECK -- CONTINUED
Test -- Continued
High cylinder pressures are caused by combustion of lu-
bricating oil in the engine 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.
5. After all 12 cylinders are checked, determine the pressure difference between high and low cylinder readings.
This variation should not exceed 70 psi. (482.6 kpa) If compression readings are below the low limit of 330 psi
(2,275.3 kpa), the engine motoring RPM should be checked to be sure that it is 140 to 180 RPM. Compression
should be checked again to confirm the previous readings before submitting an engine for overhaul.
6. Remove compression tester (3) from compression adapter (2).