350 utility hydraulic issue

[Redpaint11]

Ok guys, here’s the situation.
I had recently done a double split on this to fix the t/a seal leaks. I also pulled the hydraulic cap off and the rear end top plate to clean out the rearend and the hydraulic reservoir (it was very dirty)
I had to replace the hydraulic filter screen because it was plugged, collapsed and had tears in it.
Everything went back together well. I previously noticed the fast hitch cylinder lifted very slowly and had a bleed down fairly quickly after the tractor was shutdown.
I assumed it was a bad control valve because I hooked up the fast hitch to the second control valve and it operated perfectly.
I got a good salvage valve and after cleaning it up and replacing the o rings got it installed. Unfortunately, it is the same issue. It will lift with the engine at 50% or higher power setting but it takes 2-3 minutes to lift. The strange thing is when I hold the fast hitch control to the lift position and then activate the auxiliary control the fast hitch works perfectly. I’m stuck. Any thoughts??
Much appreciated.

 

[Mrfred54]

The unloading piston is your issue. It is located in the regulator block which is mounted on the casting right behind the auxiliary valves. The piston oring is probably hard as a rock. There is also an orfice screen mounted in the block that is probably plugged. You can put the piston in a vice and the providing pin should compress in bout 1/8 of a inch and then the orffice hole bypass should be open. I would remove the block and completely go thru it. While removing the four bolts holding the cover on, beware, it is under spring pressure. Remove two bolts and install two longer bolts before removing the existing two bolts good luck

 

[Redpaint11]

I believe I see all the parts you mentioned in the parts diagram. Sounds simple enough.
I am curious why there is only one regulator block when there are two valves. Any thoughts?

 

[Redpaint11]

update:
Removed, disassembled and cleaned the regulator. Replaced the piston o ring. The ball and spring seemed in good working order. The screen orifice was dirty but not plugged.
Reassembled and installed. Unfortunately no change in operation. Leaving the aux control locked in position allows the fast hitch to raise and lower normally but only with the aux handle.

 

[Janicholson]

The regulator valve block controls all hydraulics. there are three principle operations under consideration. The first is system max pressure limiting (necessary), the second is the control of system pressure when there is no hydraulic demand. This is the valve you are being asked to look at. It dumps all hydraulic pump output back to the reservoir, except for a small pilot pressure, This unloads the system reducing temperature and engine load. The third is a priority valve system to address the power steering requirements all the time. Jim

 

[Janicholson]

The ball can smash into the orifice hard enough and over the years, reduce the orifice size from the pounding. check that issue! the ball can be thrown away. The orifice can be drilled to between .038 and .040" to help action. Wrong viscosity non hytran compliant oil will also be a problem. Jim

 

[Redpaint11]

Jim,
Thanks for the reply. To be clear, you are suggesting to remove the ball completely but leave the spring and rider in place? Also, drilling the orifice to .038-.040. Could you please elaborate on exactly which orifice you are referring to?
Thanks,
Travis

 

[Janicholson]

layout
In the above link, 7,8,9,10 are all involved. Jim

 

[Redpaint11]

Thanks for clarifying. That’s what I was assuming. Will report back later today on status.
Travis

 

[Mrfred54]

Sorry been without internet since Wednesday Redpaint11. I see Janicholson got you covered. Good luck

 

[Redpaint11]

I removed the ball and spring from the regulator but I left the screen and orifice as is.
The fast hitch is working great now. I haven’t hooked up anything to the auxiliary valve yet but it feels like I’m on the right track. Thanks!

 

[Redpaint11]

Hey guys I’m following up again on this since I haven’t had time to mess with it in a while.
To summarize what was done and where the function is currently.
1. Removed the regulator block
2. Removed the ball
3. Drilled the orifice in the piston by .040”
4. Reassembled all
Function as follows:
Fast hitch lever when activated up or down only allows the hitch to drift down under gravity. When the auxiliary valve is activated and held in position (either up or down) the fast hitch lever then activated will operate the hitch up and down as it should.
So unfortunately after all of that I’m still not where I want it. Any other thoughts you guys might have for what to look at next would be very much appreciated. Travis