TEST OR INSPECTION
HYDRAULIC SYSTEM - CONT
SYSTEM WILL NOT MAINTAIN NORMAL OR ADEQUATE OPERATING PRESSURE
Check for general hydraulic failures.
Refer to symptom 16 for general hydraulic failures.
Check for external leaks at hydraulic fittings/joints.
After initial startup, system pressure gage (para. 2-5) reads up to 500 psi (3448 kPa) without
hydraulic controls operated.
If outside ambient temperature is below 30F (-1C), hydraulic pressure will normally be higher until
hydraulic fluid warms to normal operating temperature. A gradual decrease in pressure should occur
as hydraulic system is operated.
Check that all isolation valves are in normal operating position (para. 2-6).
Ensure valve handle operates all associated valve stems. If a valve stem is rounded off or valve is
defective, replace valve as required.
Check for partially shifted or stuck control valve handles on steering, gooseneck, and suspension
a. Operate hydraulic control valves and check for ability of valves to return to center (neutral
position). Be sure valve handles move freely and do not bind.
b. Operate suspected control valve slowly and monitor gage for pressure changes. If pressure
changes occur, valve body may be contaminated, defective, or leaking internally. Perform
general system flushing (para. 4-20) to try and move any contaminants further into system. If
symptom still exists, remove and repair or replace as required.
Identify which hydraulic control is unable to achieve normal hydraulic pressure during operation and
use Symptom Index for quick reference to continue troubleshooting.