Hydraulic pumps getting hot

[MParr]

Find the manual for your particular pumps.
From: Parker Hannifin
“Hot oil” is a relative term. In most cases, 120° F
(49º C) at the reservoir is considered an ideal operating
temperature. Always take an oil temperature reading
at the reservoir, not at a component or any of the
piping. Some hydraulic systems are designed to
operate at 130° F (54º C) or higher. If you don’t
know the maximum operating temperature for your
equipment, check your component manual for
temperature and viscosity limitations.

 

[Skippydiesel]

Find the manual for your particular pumps.
From: Parker Hannifin
“Hot oil” is a relative term. In most cases, 120° F
(49º C) at the reservoir is considered an ideal operating
temperature. Always take an oil temperature reading
at the reservoir, not at a component or any of the
piping. Some hydraulic systems are designed to
operate at 130° F (54º C) or higher. If you don’t
know the maximum operating temperature for your
equipment, check your component manual for
temperature and viscosity limitations.

Good stuff MParr. In particular the location (reservoir) to assess the temperature.

Only thing I would add is;

This applies to the oil that came with or recommended for, the system - it's not unusual for the OM oil to have been replaced with something diffrent. Added to this is the ever changing formulations that may be used.- Check with the oil manufacturer for your oils optimum operating temperature range - be sure to mention this is for a hydraulic system, not an engine.

 

[ILENGINE]

Not unusual for hydraulic oil to be 100 degrees above ambient air temperature. And with a hydrostat system they are not continuous flow from pump to cooler to tank. Depending on efficiency of the system most of the oil gets return between the pump and wheel motor multiple times before returning to tank. for filtration and return to system.