One of the most common, hydraulic systems issues we help our customers troubleshoot is hydraulic systems running too hot. More often than not, this is due to having a pressure-compensated pump and the fluid being dumped over the relief rather than over the compensator- creating heat.
To learn more, watch this short video of John Henry Foster's hydraulic guru, David Granade- Fluid Power Specialist, as he goes into more depth- explaining this issue, the solution, and some hydraulic fundamentals.