325C Excavator Hydraulic System Gear Pump (Pilot) - Test Caterpillar

Gear Pump (Pilot) - Test

Illustration 1g00817931

Flow meter tool layout

(1) Swing motor

(2) Connector at swing motor

(3) 6V-9840 Swivel tee

(4) Makeup line (swing motor)

(6) 6V-9509 Face seal plug

(7) 4C-9910 Portable hydraulic tester (flow meter)

(8) Pilot line (delivery line from the pilot pump)

(9) Connector at pilot pump

(10) Pilot filter

(14) Pilot pump

(30) 5K-9090 O-Ring seal

(31) 5P-0201 Hose

(32) 5P-1010 Sleeve

(33) 4C-8767 Coupling

(34) 7M-8485 O-Ring seal

(35) 4C-6481 Coupler assembly

(36) 4C-6482 Nipple assembly

(37) 4I-6141 Coupling

(38) 8C-9026 Adapter

(39) 6K-6307 O-Ring seal

(40) 6V-9854 Swivel elbow

(47) 4I-6140 Coupling

(48) 8C-8762 Elbow

(49) 6V-8398 O-Ring seal

------ WARNING! ------

To prevent personal injury or equipment damage from failure of the hydraulic test equipment or associated circuit components because of blocked pump flow, make sure that the test equipment valves are fully open before starting the engine.



Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.

Refer to Special Publication, NENG2500, "AVSpare Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids on AVSpare products.

Dispose of all fluids according to local regulations and mandates.

  1. Position the machine on level ground.

  1. Stop the engine.

  1. Release the pressure in the hydraulic system. Refer to Testing and Adjusting, "Hydraulic System Pressure - Release".

    Illustration 2g00817936

    Circuit diagram

    (1) Swing motor

    (2) Connector

    (3) Tee

    (4) Makeup line

    (5) Main control valve

    (6) Plug

    (7) Portable hydraulic tester

    (8) Pilot line

    (9) Connector at pilot pump

    (10) Pilot filter

    (12) Engine

    (13) Multitach group

    (14) Pilot pump

    (40) Elbow

  1. Install the following tools in accordance with the flow meter tool layout and the circuit diagram. Refer to Illustration 1 and Illustration 2.

    1. Install multitach group (13) on engine (12) .

    1. Remove pilot line (8) from connector (9) at pilot pump (14) .

    1. Install seal (49) and plug (6) to the end of pilot line (8) .

    1. Install seal (49) and elbow (48) to connector (9) at pilot pump (14) .

    1. Install seal (34), coupling (47), seal (34) and nipple assembly (36) to elbow (48) .

      Illustration 3g00669270

      Swing motor

      (1) Swing motor

      (2) Connector

      (3) Tee

      (4) Makeup line

      (40) Elbow

    1. Disconnect makeup line (4) from connector (2) at swing motor (1) .

    1. Assemble and install seals (30), tee (3), swivel elbow (40) and coupling (37) to connector (2) at swing motor (1) .

    1. Connect portable hydraulic tester (7) and test hoses between nipple assembly (36) at the pilot pump and coupling (37) at the swing motor.

  1. Start the engine.

  1. Place the machine controls at the following settings: engine speed dial "10" and AEC switch OFF. Refer to Testing and Adjusting, "Engine Performance - Test" for engine rpm settings.

  1. Increase the hydraulic oil temperature to 55° ± 5°C (131° ± 9°F).

    Illustration 4g00344084

    Portable hydraulic tester (flow meter)

    (7) Portable hydraulic tester (flow meter)

    (13) Multitach group

    (16) Valve (flow meter)

  1. Turn valve (16) on portable hydraulic tester (7) clockwise until the pressure gauge on the portable hydraulic tester shows a reading of 4100 ± 200 kPa (595 ± 29 psi).

  1. Record the pilot pump flow at 4100 ± 200 kPa (595 ± 29 psi) in Table 1.

Table 1
Pump Flow Test    
Oil Temperature C° (F°)        
Engine Speed (rpm)        
Flow Measured liter/min (US gpm)        
Flow Corrected liter/min (US gpm)        
Specification for Pump Flow liter/min (US gpm)     New    
36 ± 2 (9.5 ± 0.5)    
Service Limit
30 (7.9)    

Note: Specifications for pump flow are based on an engine speed of 1800 rpm. To get more accurate test results, measured flow should be corrected by the following calculation.

Table 2
Corrected flow     =     Measured flow x 1800 rpm    
Measured rpm

Flow measurements must be done in pressure rise.

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