1993 gen V set up
I have been having the power steering fluid blowing out of the cap since last year. It was on a stock steering system last year when it started. I installed external steering rams this year (still have the cables to the steering wheel). Problem still persists may add fluid every 4 times out. It defintly gets worse over 5000 rpm. I did replace the cap with a good used one from another boat. (I noticed there is not a breather hole in the top of the cap alike the older GM car caps)
Today it blew off even worse. I did switch to hydrolic fluid. not sure if that is good or not.
Is thre a better cap? should I just replace the pump? Can I use a replacement pump from NAPA keeping the housing?
Thanks

do you have a cooler on the power steering? either a stand alone or one built into the oil cooler?

Do you have an external fluid tank?
Thanks
Steve

It sounds like it has air in the system. It only takes a little bit to make one puke. I would bleed it very carefully. Hook the engine to a hose and have a friend watch the reservoir. start the engine and turn the wheel very slowly one way to lock. Add fluid as needed. Turn the wheel the other way very slowly to lock. Keep repeating until there are no bubbles present. You must not let the system run dry. You may need to circulate it several times. Be patient and it should solve the problem. The steering pump needs to be marine.

i think the pump is a standard gm pump,i have 2 boats and both use a standard gm pump.

When I installed external steering, I didn't need to bleed the system. Just had the motor at idle on the hose, and kept cycling the steering full right to full left while topping off the reservoir as it got sucked down. My system is full hydraulic, no external reservoir other than the standard marine gm ps pump. By the way, there is a difference between the marine gm ps pump and the auto gm ps pump. Inners are the same, but the outlet boss of an automotive pump is not compatible with the mercruiser gm pump.

I suspect your bypass valve has failed. This happened to me and the behavior of boiling the steering fluid was the same as yours. I replaced the valve on the pump and problem went away. What happens is the pump cannot go into bypass mode causing the pump to be deadheaded, then cavitate which superheats the fluid.

I meant the auto pump is not compatible with the standard mercruiser ps hose...