PUMP GP-GR A 4689887 - Caterpillar

Illustration 3 g01779774
Install Tooling (A) on pressure taps (R7) and (R8) .Test Procedure - Pressure Override (POR) Valve
Start the engine and run the engine at HIGH IDLE. Record the engine speed into Table 1 of the "Specifications".
The reading on pressure gauges at pressure taps (R7) and (R8) should be 3300 150 kPa (478 22 psi). If either pressure is higher, then the charge pressure relief valve is improperly adjusted or faulty or the oil temperature is too low. If the pressures are too low, then there is a problem in the charge circuit. This problem could be caused by one of the following reasons.
The charge pressure relief valve is improperly adjusted or failed.
There is a leak in the charge circuit.
The motor or the motor flushing valve has wear.
The cold start valve is worn or improperly adjusted.
The oil level is low.
The charge pump is worn.
The steering pump is worn.
Make sure that the transmission is in NEUTRAL. Disengage the parking brake and fully activate the service brake.
With the engine at HIGH IDLE, slowly move the steering control lever to the MAXIMUM STEER RIGHT position. The steering system is in a STEER STALL CONDITION.Note: Do not hold the machine in a STEER STALL CONDITION for more than 20 seconds at a time.Note: The machine must not move. If the machine moves, the brake system must be checked.
With the machine in a STEER STALL CONDITION, read the pressure at tap (R8) and the engine speed. Record this pressure and the engine speed into Table 1 of the "Specifications". This pressure should be 45300 1140 kPa (6570 165 psi).
With the engine at HIGH IDLE, slowly move the steering control lever to the MAXIMUM STEER LEFT position. The steering system is in a STEER STALL CONDITION.Note: Do not hold the machine in a STEER STALL CONDITION for more than 20 seconds at a time.Note: The machine must not move. If the machine moves, the brake system must be checked.
With the machine in a STEER STALL CONDITION, read the pressure at tap (R7) and the engine speed. Record this pressure and the engine speed into Table 1 of the "Specifications". This pressure should be 45300 1140 kPa (6570 165 psi).
If the pressure at tap (R8) and the pressure at tap (R7) are incorrect, the cause may be listed below.If the pressure at tap (R8) and the pressure at tap (R7) are higher than the specifications, the pump cutoff pressure needs lowered. Additional causes may be listed below.If the pressure at tap (R8) or the pressure at tap (R7) is lower than the specifications, the cause may be listed below.
The pressure over-ride valve is misadjusted or failed.
The motor flushing valve is stuck or the valve is not functioning properly.
The motor is worn or leaking.
The charge pressure is low.
The pump is worn or leaking.
The crossover relief and makeup valve is leaking or the crossover relief and makeup valve is set too low.
If the engine speed drops more than 30 rpm in either