I got a cat 312 trackhoe hyd. Overheat, if you start the machine let it idle with the saftey handle down in about 2 hours the hyd. System will get hot , if you work the machine it takes about 20 minutes, engine temperature stays normal replaced hyd by pass valves,
check Hydraulic pump and Hydraulic cooling system
Put gauges on main pump pressure see if you have high stand by pressure. Did you change return filters?
Changed return filters, checked cooler 15 degrees difference in the inlet and outlet
Was the temperature difference with hot oil and decent rpm?
Post serial number what's cooler in let temp
Whats the serial number of the 312 ?
S/n 8JROO715 and after just running it for about 10 minutes inlet temperature is 156 ant outlet is about 140 and the longer you run it the hotter it gets then engine temperature stays normal
156 inlet temperature and outlet temperature is 140 at the hydraulic cooler