TROUBLE SHOOTING WITH THE HYDRAULIC TESTER
PRELIMINARY:Check oil level in tank, pump drive, valve linkage for damaged parts, external
oil leaks etc
Problem
Possible Cause
Suggested Test,
See Paragraph:
Excessive pump noise
Pump cavitation caused by:
fluctuating pressure
a) Clogged suction filter
3.0; 4.1
b) Restricted suction line
Low flow under no load
c) Air leak in pump suction line,
fittings, shaft seals etc.
d) Pump speed too high
Decreasing performance
Internal leakage in:
as pressure increases
a) Pump
3.0; 4.1
on all circuits
b) Main Relief Valve
4.2; 4.3
On one circuit
c) Directional Control Valve
4.2; 4.3; 4.4; 5.0
d) Cylinder or Hydraulic Motor
5.1; 5.2
Fails to hold load
Directional Control Valve
4.2; 4.3; 4.4; 5.0
Cross line Relief Valve
5.02
Cylinder
5.0; 5.2
2
