4430 Deere is a Closed center demand system. If oil isn't being 'demanded', oil isn't flowing.

I run a 90' boom at 10 mph with an Ace on a 4030. Gets warm, but not hot.

What I do though, and may pertain to you is only run enough flow at the outlet to provide the solution flow/pressure I need. Keep turning the rabbit / turtle lever on the back towards the turtle until you lose pump performance. It will reduce unnecessary hydraulic flow, and therefore heat... If its spinning flat out and you cant supply a 60' boom, you have impeller/volute problems.

Hope I'm not off base here. 

Ken