Hitachi ZX 160LC-3 Power Loss Under Load

I have a 2010 Hitachi zx 160 lc-3 that will run perfect for 45 minutes or so before warning light comes on and all hydralic power is loss. Engine will run fine at high or low RPM's at this time as long as it not under a load. I shut it down and let it sit for a few minutes and back to work it goes for 10 minutes or before doing it again. After sitting over night it works fine agian for 45 minutes to 1 hour or so

Hitachi ZX 160LC-3 Power Loss Under Load