HELP weak pump or worn lift cylinder?

[itsmesrd]

I've finally got the water out of the system and discovered that that didn't solve my problem. I have to rev the engine very high to get the 3-point to pick up the bush hog or anything that I hook to it. Even at higher revs the thing still leaks down and will not pick it up until I work the lift lever down and back up. Is the pump weak or the lift cylinder worn out?
This is my first tractor and I'm not up to speed of the where and why of things hydraulic.

 

[Dave M7040]

I've finally got the water out of the system and discovered that that didn't solve my problem. I have to rev the engine very high to get the 3-point to pick up the bush hog or anything that I hook to it. Even at higher revs the thing still leaks down and will not pick it up until I work the lift lever down and back up. Is the pump weak or the lift cylinder worn out?
This is my first tractor and I'm not up to speed of the where and why of things hydraulic.

If you are going to trouble shoot a hydraulic system at the very minimum you need to get a pressure gauge and quick connect fitting so you can see what pressure the pump is delivering or the relief valve set at.

Most local hydraulics shops, the people who make up hoses, have what you need and the cost will be about $30.

To test the pump and relief valve, plug the new gauge into a rear remote or even a front end loader quick connect fitting, rev the engine to full speed, send fluid power to the port where the gauge is installed and note the reading. If you are not going to be able to see the gauge from the driver's seat, have the hydraulics shop put a length of hose on it so you can plug in in and hold the gauge

Often having another hydraulic lever out of position, such as one for a rear remote can be draining the system flow and pressure.

Plse post some photos of your tractor so we can see what equipment it has or features.

Dave M7040

 

[LD1]

Usually a 3PH valve is what is considered position control. And has a feedback linkage connected to the rockershaft arm.

Meaning that even if a valve or cylinder is leaking causing the implement to slowly drift to the ground, it should auto-correct itself and keep it at whatever position you have it set at.

A long shot......dont know if that tractor has one.....but most modern tractors have a knob to adjust drop speed for the 3PH. It is usually located in front of and right under the seat. If the tractor has one.....raise the implement all the way up and turn that valve ALL THE WAY off. That should isolate the valve from the cylinder and make it so lowering the valve WONT lower the hitch.

Now if it still leaks down, the cylinder is the issue. But if shutting that speed control valve off and it no longer drifts down, that points to a faulty valve.

 

[itsmesrd]

This little tractor is hard piped from the pump to the top of the transmission case that houses the 3ph lift cylinder. So no remote place to plug in a gauge. I would have to cut into the high pressure line or make some sort of adapter to bolt onto the end. There is "flow control knob" on the right side of the lift housing, but it seems to be frozen in place. I've tried tapping it lightly and squirted WD40 at the threaded portion that is showing. I'll try and move it again this morning.
Right now it's a real pain in the butt to have to keep working the lift lever to get the 3ph to go up and stay. If it drifts down while moving the tractor I have to stop and lower it completely before it will raise for me. Could the wrong oil cause this? The fellow that I got the tractor from said that it uses 303 spec hydraulic oil. The entire transmission seems to be bathed in this oil can anyone tell me if this is correct or should I use something else. Hydraulic oil seems very thin for transmission service.

 

[LD1]

Most tractors us a form of hydraulic oil for transmission. Yes its thin. Shouldnt cause your problem though, but thinner oil make symptoms of a leak more pronounced.

 

[itsmesrd]

Thanks LD1, I was a little worried that I may be using the wrong oil. I wish that there was an easier way to check pressure. Guess O'll just have to bite the bullet and try and make an adapter to bolt to the cylinder end of the piping. Or could I place it at the pump end? Not too worried about the high pressure pipe being clogged.

 

[LD1]

Get that flow control knob working first and foremost

 

[itsmesrd]

It stubbornly refuses to budge. Maybe a little heat and more tapping. THEN the ole pipe wrench treatment.

 

[LD1]

Careful with the heat. Don't want to melt any seals

 

[itsmesrd]

The book shows a steel ball at the end of the knob and an o-ring, so I'm not too worried about getting it too hot but at the same time I don't want to burn the paint off either. The knob if it can be called that is more of a thumb screw looking thing. Not much to grab hold of.