Hydraulics
Why do the hydraulics weaken when hot?
If hydraulics work cold but become weak or slow when hot, thinner oil may reveal internal leakage or wear. Diagnosis must therefore take place at operating temperature. A good cold result is not enough.
Compare cold and warm operation
Compare pressure, function speed, engine speed, pilot pressure and pump control under the same conditions, first cold and then fully warmed up.
Why heat reveals the fault
Oil viscosity falls as temperature rises, increasing leakage through worn clearances in the pump, control valve, other valves, cylinder or hydraulic motor. Good cold operation does not prove these parts are sound.
Main pump
A pump may develop pressure cold but lose flow hot, with increased case drain or noise. Measure pressure and case drain using the manufacturer’s procedure.
Valves and control valve block
Contamination, worn seats, a sticking spool, main or local relief leakage and internal valve-block leaks are possible. A contaminated valve may seal better with thick, cold oil.
Cylinder or hydraulic motor
If one function weakens, its cylinder or motor may be responsible. Leaking piston seals or a worn hydraulic motor may become more noticeable when hot.
Measure at the specified temperature
Measure and adjust at the manufacturer’s operating temperature. Adjustment on cold oil may be wrong once the system is hot.
What you can observe
How long before performance drops? All functions or one? Is force, speed or both lost? Does the oil overheat, does the pump get noisier hot, and does performance return after cooling?
Related problems
Further service support
Problem still there?
If these checks have not identified the cause or the fault returns, contact TSV Servis. The more initial information you provide, the sooner we can identify the next diagnostic direction.
What to send us
Send cold and hot pressures, oil temperature, affected functions, pump case drain where required and pump control data at operating temperature.
Include the make and model, S/N or a nameplate photo, engine model if known, operating hours, exact code or display photo and when the fault occurs.
Also tell us what you have already checked or replaced and the results. Include a photo or short video of the symptom where useful.
+420 722 307 850 · tsvcz@seznam.cz