BobCat 753 – HYDRAULIC PUMP (CAST IRON) – Check The Output Of The Hydraulic Pump With Power Bob-Tach

The tools listed will be needed to do the following procedure:

MEL1563 – Remote Start Tool
MEL10103 – Hydraulic Tester
MEL10106 – Hydraulic Test Kit

Lift and block the loader. (See LIFTING AND BLOCKING THE LOADER on Page 10-10-1.)

Raise the lift arms and install an approved lift arm support device. (See Installing Lift Arm Support Device
on Page 10-20-1.)

Raise the operator cab. (See Raising The Operator Cab on Page 10-30-1.)

Open the rear door of the loader.

Connect the remote start tool. (See REMOTE START on Page 10-60-1.)

Disconnect the OUTLET hose (Item 1) from the fitting (Item 2) [Figure 20-61-6].

Place the hydraulic tester as shown in [Figure 20-61-7].

Route the inlet hose (Item 1) [Figure 20-61-7] from the tester, between the hydraulic reservoir and the blower
housing to the gear pump.

Connect the INLET hose (Item 1) [Figure 20-61-7] & [Figure 20-61-8] from the tester to the OUTLET fitting
(Item 2) [Figure 20-61-8] on the Power Bob-tach block.

Connect the OUTLET hose (Item 2) [Figure 20-61-7] & [Figure 20-61-9] from the tester to the hose (Item 1)
[Figure 20-61-9] which was disconnected from the Power Bob-tach block.

Sample tester connection shown [Figure 20-61-10].

Start the engine and run at low idle RPM. Make sure the tester is connected correctly. If no flow is indicated on the
tester, the hoses are connected wrong. With the hoses connected correctly, increase the engine speed to full RPM*.

Warm the fluid to 140°F. (60°C.) by turning the restrictor control (Item 1) [Figure 20-61-10] on the tester to about
1000 PSI (6895 kPa). DO NOT exceed system relief pressure. Open the restrictor control and record the free flow (GPM) at full RPM.

Turn the restrictor control (Item 1) [Figure 20-61-10] on the tester to the system relief pressure.

NOTE: Do not exceed system relief pressure, damage to the hydraulic system may occur if pressure is exceeded.

Record the flow (GPM) at system relief pressure. The high pressure flow must be at least 80% of free flow.

A low percentage may indicate a failed pump.

*Refer to SPECIFICATIONS Section SPEC-01 for system relief pressure and full RPM.


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