pump seems to "deadhead" when loader attached

namesray · Apr 23, 2012

my father in laws jinma 354 tractor hydraulic system is throwing him fits. the orginal hydraulic pump went a bit ago. he put a new one in and the first one burned up. second one still not operating correctly. he says when he feels pump it is getting hot.

when the loader is attached the hydraulic pump gets hot. the loader will move in the correct directions, but not operate correctly. also the 3ph does not operate when the loader is hooked up. take the loader off and connect the hoses up for return flow for the open center hydraulic system, the tractor runs fine and 3ph runs fine. when the loader is hooked up, 3ph only works when loader control valve is moved and while the tractor is running and loader control valve is in "neutral" that is when it deadheads and heats up. if the loader valve was worked the entire time (up, down, curl, dump), the pump does not heat up. kinda a mystery, atleast for us.

he had a hydraulic repair guy tear the loader control apart and clean the "boxes" and check all o rings and whatnot and everything looked ok. put back together and still a problem. even cleaned out the small holes in the loader control valves that direct flow to move the loader. even has the hydraulic guy stumped.

my father in law says there is a pressure set screw?? on the loader valve and he has tried it both directions and no different. like i say, it does not deadhead when loader is taken off. must be something in loader control valve restricting flow or the power beyond return??? father in law is a tool and die maker by profession and we both understand some about hydraulics, him more then i, but we are all stumped. any ideas?

olde man · Apr 23, 2012

not quite sure how you're set up, having yo switch lines and all but it sounds like your pb line isn't going where it should just a guess

J_J · Apr 23, 2012

Check and see if the PB port requires a screw inside the PB port to block off the galleries, if missing, that would mean that all the fluid from pump and cylinders would go to the tank even though the PB hose is connected.

If the PB port uses a PB sleeve, ensure both o-rings are there.

The PB sleeve will look like this.

http://www.surpluscenter.com/Wire/W9-7550.jpg

PB screw will look like this.

Surplus Center - P-BEYOND & CLOSED CENTER PLUG 8 GPM MB VALVES

When you remove the loader, you must be connecting the pump pressure hose directly to the 3pt input line, which is the way it comes from the factory.

The return port goes to tank. .

MH49 · Apr 25, 2012

What is the plumbing order? Does it go pump - 3PH - loader or pump - loader - 3PH?

Does your 3PH continue to operate when the loader function is dead headed (I.e. a cylinder fully extended) or does it stop when the loader stops?

J_J · Apr 25, 2012

His return outlet on the loader appears to be connected to the 3pt, and that is why it only works when someone moves a loader leaver. If the FEL has PB, that hose probably is going to tank.

When he removes the loader, and connects the pump hose to the 3pt, it works like it is supposed to.

MH49 · Apr 25, 2012

J J, I think we are on the same page but it seems to me like the 3PH is hooked to the tank line of the loader valve and the power beyond is blocked. That would explain why you have high pressure in neutral and the 3PH only works when the loader is functioning. If this is indeed the case then the OP is pressurizing the tank core of the loader valve which is never a good thing.

J_J · Apr 25, 2012

namesray,

Remove all hoses from FEL valve and use air to check out the valve.

Connect air to the IN port of FEL valve.

If the valve has PB installed, in neutral, air will exit the PB port.

If no PB installed, or PB port is plugged, air will come out the tank port.

If you activate the lever, air will exit one of the work ports.

If air does not exit the PB port in neutral, you may have a closed center plug installed.

If PB port is installed but some one has plugged the PB sleeve, you now have a closed center valve.

Most all tank ports should go to tank.

How long have you ran the tractor with the loader installed?

If the PB is blocked for some reason, then the pumps flow would flow across the relief on the FEL valve, and you did say it felt hot.

namesray · Apr 25, 2012

thanks everybody so far. don't want you all to think i posted and abandonded you all. i have been reading and passing the info on to my father in law. we don't see each other that much, so this process might take a little bit. he was going to start working on it sometime today if he got a chance. all info sounds good and hope we solve this soon. seems like i learn something new everytime i am here on tbn. thanks all for your help and i will keep you posted.

namesray · Apr 26, 2012

update to finish this one out.

father in law worked on it last night and says he got it fixed. i told him what you guys said about the set screws and the power beyond blocked or not right. he found some set screws/caps on the loder valve control somewhere (i think as he told me the story), anyway he backed them out and fluid just started leaking out. in one of them he noticed there was more space then what the screw would go in, so he put a wire through it and got a "needle" valve like thing out along with a spring about the size you find in a writting pen. (please excuse me if i don't get this just right.) this "needle" valve like thing had black gunk clogging the hole that the hydraulic fluid would flow back for pressure relief/power beyond. he thought this black gunk might be an old o ring that got forced in when he worked on the pumps before and turned up the pressure. any way he cleaned this all up and put it back together and now it seems to work fine. everything. 3ph works normal and pump stays cool. he is very happy to have this problem solved and off his mind. thanks to all who helped along the way.:thumbsup: