Weak power steering on MF40

Jaypat88

Member
Bought a MF40 Industrial that had weak power steering. I
replaced steering pump and still have weak power steering in
that the wheels will turn when front end is lifted but not strong
enough to overcome resistance when wheel is braced by
hand. I spent 30 min of trying to get all air out of lines per
manual instructions. I am thinking I need to test the pump
pressure. Manual identifies the line I connect to for testing.
Do I splice into the line with a tee or one side of the line? Will
this test the system pressure or the pump pressure? How do I
make sure my new pump is opperating correctly? There is
also a small slow drip in one steel hydraulic line, but would not
think it would weaken my steering that much but maybe it is?.
Manual also says I can adjust the relief valve to add or
decrease pump pressure. Where is the valve located? I
attempted to check pump pressure on bottom inlet of pump
but fluid came out of the hose that I disconnected. Manual
said bottom inlet was the pressure line.

Could my problem also be in my steering assembly? There is
a good amount of whining during turning the steering wheel
that comes from the steering assembly.

What is the process to troubleshoot this problem?

Thank you for all your help!
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There is
also a small slow drip in one steel hydraulic line, but would not
think it would weaken my steering that much but maybe it is?.
When there is a hole that oil can come out, then air can go in and make oil foamy and nothing works.
 
According to Big Dean's cd, you can just put a pressure gauge on the outlet in place of the line and run it just long enough to get the setting. Sorry, don't remember setting. Will be listed in manual as well as the location of valve. It's on the side of the pump, inside the canister. Think it's a large slotted screw, about 5/8" dia with a jam nut on it. Turn in for more pressure or out for less. Could be set wrong from the supplier. Could also be the steering cylinders are bypassing internally.
 
Ok, that's what I was originally wanting to do. I took off the bottom line from the pump and directly screwed the pressure guage in that inlet. However, when starting the engine fluid sprayed out the line I just removed. Manual shows the bottom line being the pressure line. Could I have the lines reversed?

Thank you
 
I would think the pressure line will go to the control valve (steering wheel) first and from there back to steering cylinders. No manual close by here.
 
It's possible i guess. If the fittings are the same size you could have them backwards. Bad whining in a pump is normally one of two things.
1) Lots of air in the system for whatever reason and causing it to cavitate.
2) Serious pressure feedback. If you have ever gotten a car stuck in the snow and you try to turn the wheels and it screams at you... that is the pressure feedback from the stuck tires. Likewise if you are at steering lock and try to push it further the pump screams at you for the same reason.
 
OK, I replaced the cracked power steering line. Refilled Power Steering Pump and felt like I had more pressure in lines during the steering. Still not enough pressure to turn the wheels without the front end lifted. I did notice some oil on the hydraulic cylinder cap assembly and the wheels would turn about an inch and move back an inch as if it lost pressure. If I continued to spin the wheel pressure would fluctuate in effort to turn the wheel with some reflex. Thinking it may be the seals on the cylinders. Hydraulic shop said I could take both lines off cylinder and put a air pressure hose to one inlet and if I feel air come out of the other hose then the seals are bad. Anyone ever try this method?
 

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