Section E - Hydraulics
Problem Solving
Loader/Excavator Circuit
E-70 E-70
9803-9340-8
Loader/Excavator Circuit
The purpose of this section is to help you trace hydraulic
problems to a faulty unit (valve, actuator,ram, etc). Once
you have traced the faulty unit, refer to the appropriate
dismantling, inspecting and test instructions given
elsewhere in the manual.
1 Before you begin problem solving, read the Safety
Information at the beginning of this manual.
2 Make simple checks before removing and/or stripping
a major component.
3 Make sure that the hydraulic fluid is at correct working
temperature (50 ºC, 122 ºF).
4 Whatever the fault, check the condition of the
hydraulic fluid. Drain and replace if necessary.
5 Be sure to remove ALL contamination and if possible
identify its origin. It may be part of a component from
elsewhere in the circuit.
PROBLEM CAUSE
Lack of power an all loader/excavator functions 1, 2, 3, 4, 5, 6, 7, 17
All hydraulic rams slow to operate 1, 2, 3, 4, 7, 9, 10
One hydraulic service fails to operate or operates slowly 11, 12, 13, 14, 15, 16
Engine tends to stall when hydraulics are under load 3, 17
Valve spool sticking 3, 19, 20, 21, 22, 23, 24, 25, 26
Ram creep 10, 12, 15
Hydraulic oil becomes too hot 1, 3, 5, 6, 9, 18, 27
KEY TO CAUSE REMEDY PAGE REF.
1 Insufficient hydraulic oil Check for leaks and top-up as required.
K Hydraulic
System ( T 3-43)
2 Hydraulic leaks in system Check hoses, replace as required.
3 Main relief valve (MRV) setting incorrect Check and adjust as required. K Pressure
Testing ( T E-140)
4 Low service pump flow Check pump flow ensuring engine is at correct
speed. If necessary service or replace pump.
5 Hydraulic filter clogged Change hydraulic filter. K Changing the
Hydraulic
Filter ( T 3-44)
6 Filter by-pass valve leaking Check condition of hydraulic filter. Check
operation of by-pass valve.
7 High suction pressure Check for restriction in suction hose.
8 Neutral circuit or low pressure lines
leaking or damaged
Check pipe lines and replace as required.
9 Restriction in neutral circuit lines Check for kinked, trapped or cruched hoses and
pipes, correct as necessary.
10 Air in hydraulic system Bleed system.
11 Service pipe lines leaking, damaged,
trapped or kinked
Check hoses and pipes, replace as required.
12 Ram or pipe lines from ram leaking Check and rectify as required
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