SPRING 6P6630 - Caterpillar

Measure the cylinder pressure of new engines. Record the data. Continue to measure the cylinder pressure periodically. Comparing the recorded data to the new data provides information about the condition of the engine.Cylinder pressure can be measured during inspection of the spark plugs. Use the following guidelines for checking the cylinder pressure:
Remove all of the spark plugs.
Fully open the throttle plate.
Minimize the cranking time to three or four revolutions which will enable a maximum consistent cranking speed for the check. Also, the battery power will be conserved.A loss of cylinder pressure or a change of pressure in one or more cylinders may indicate the following conditions. These conditions may indicate a problem with lubrication:
Excessive deposits
Guttering of valves
A broken valve
A piston ring that sticks
A broken piston ring
Worn piston rings
Worn cylinder linersIf the cylinder pressure has risen by one or more compression ratios, the engine needs a top end overhaul in order to remove deposits. Failure to remove the deposits will increase the chance for detonation. Severe guttering of the valves will occur.To measure the cylinder pressure, use the 193-5859 Cylinder Pressure Gauge Gp. Follow the procedure in the Special Instruction, NEHS0798 that is included with the gauge group. Record the pressure for each cylinder. Use the Operation and Maintenance Manual, "Valve Data Sheet" (Reference Materials Section).Illustration 1 is a graph of typical cylinder pressures for engines with different compression ratios.
Illustration 1 g00828960
(Y) Cylinder pressure in kPa
(X) Compression ratio
(1) Normal range for cylinder pressure