power steering fluid over heating

installed a new power steering pump , valve, cylinder and hoses. As soon as the engine is started the power steering fluid starts getting extremaly hot. Too hot to touch. Any idea. I have primed the system more than once, Have changed the pump and valve with good parts. What have i done wrong. I let the engine run for about a minute and used my infared heat gun and the temp was around 400 and rising. Only thing I have not changed are the lines. 

Hi Steve,

I'm sorry I don't have an answer for you.  I'm a little surprised that some of the more tech savvy folks haven't jumped in here and tried to offer up some of their knowledge.  Hopefully someone will chime in soon.

Power steering pumps create a LOT of pressure. Anytime you compress a fluid, that fluid will get hot....it's simple physics. How hot is too hot? Can't say I've ever known the answer to that one. I CAN tell you that transmission fluid will start to break down at temps over 260F. That fluid will also expand the hotter it gets, and eventually will start puking from any available escape route. If your fluid is actually running at 400deg, I would expect it to be spitting everywhere. I wouldn't recommend attempting to touch power steering fluid with the pump running to see how hot it is anyway.....just take it on faith that it will be HOT! 

Does the steering system work ok, with no leakage? If so, then I would suggest let it be, or, if you want, you could add a cooler to cool the fluid a little more. Most later model vehicles have p/s steering coolers from the factory.

I’m having the exact same issue with my 77c3 please let me know if you figure it out!? & I’ll be sure to do the same!

thanks, Dave

This says to route the pressure hose back to the return on the pump and see if it gets hot.

https://www.yourmechanic.com/question/the-fluid-in-the-power-steering-pump-is-overheating-by-wilhelm