Help. Tractor hydraulics weak

[Mill Lee farm]

Hello. Hopefully there are hydraulic guru’s here that can help.

My compact Kioti CK20HST suddenly lost power and speed in the loader and 3-point. Hydro drive and steering seem ok but it’s hard to say.
Engine runs normal.

I drained hydraulic fluid and changed the 2 filters (hydro drive has it’s own)
Fluid looked dark.

Hydraulics are better but far from normal.

I rigged up a pressure test gauge to the rear remote and psi definitely seems very low! 1500psi max?
Also seems to spike then slowly drops. I feel like that could suggest something?

Please give ideas? Is the pump shot? ($800!!!) Pressure relief valves stuck open? Other?



View attachment trim.A1A6FBD6-41DB-486F-8F6F-812DFCE72C85.MOV

 

[solo]

That is very odd! I can't even guess what's happening. Hopefully someone here can help.

 

[tq60]

Check simple first.

Pressure relief can do this if it gets something in it when you hit the limit of motion and the relief is used.

So, with nothing attached, operate valves to force the relief to open.

Placing a gage on a quick connection works great for measuring.

I
Open then return to normal. If your gage is at an attachment point, you need to open a valve to read it.

SOME are adjustable. They usually do not self adjust, but worth a shot just in case.

Other possibility is worn pump.

Our Bobcat 825 has this, the pump is a couple gears in a casting with a flat plate over the end.

Ours is anyway.

The plate was worn as was everything else.

Sandpaper on glass allowed me to get the plate flat.

Same for the housing, got it flat, and removed some of the height so less blow-by so better output.

Needs new pump but it works well enough for us.

Troubleshoot first, then determine cause of failed item.

Pump may be worn or bad seal.

Or, could be filter or getting air in.

Sent from my SM-G781V using Tapatalk

 

[rabler]

May give you some ideas:

 

[Nutfarmer]

If the steering is working , the charge pump is most likely ok along with the filters and pickup tube. If you still have the old filters cut them apart and look for metal. Most likely the main hydraulic pump went out. Sounds like the same symptoms my 9545 Kubota had when the pump went out. If the pump is easily accessible pull it and take a look. It is probably a simple gear type pump. Excessive wear should be obvious. The shaft bushings on the gears and the cover plate will probably show wear the first. Good luck. Any parts for a tractor have become expensive

 

[gard]

Is there a separate filter or screen on the inlet side of the pump? Any restriction or air leak on the inlet side of a pump can cause all kinds of problems as well as cavitation damage to the pump.
What is the spec for pressure in your system? 1500 psi may not be that far off depending on age of the tractor.
Your pump should also have a spec for flow.
You can put a valve after your gauge then have it flow back into transmission, start engine and adjust valve to the spec pressure then pull the return out of the transmission and measure how long it takes to partially fill a 5 gal bucket. Clean up the mess.
Some hydraulic pumps are rebuildable some are replaceable.

 

[pontiac428]

How many pumps are in the system? There may be more than one, you have the drive components working, very likely a separate pump and circuit. Pumps can be stacked in a common case with a common shaft and be hydraulically isolated, separate pumps.

Once you complete your thorough troubleshooting and decide if it is needed, I'd encourage you to rebuild your own pump. Gear pumps wear the thrust plate and sometimes the gears, vane pumps wear the side plates, vanes, and pump walls. I think that most people who frequent this site can do a rebuild without paying someone else to do it.

@Mill Lee farm, I have a really good reference book on hydraulic systems I could email to you if you are interested.

 

[aliva]

There could be many reasons why the pressure is low, from a bad relief valve bypassing pump and bypassing cylinders.
Start with the oblivious. Fluid level, external leaks, either hoses valves or cylinders.
Check what the max pressure is supposed to be.
install a pressure gauge and bottom out a cylinder either extend or retract doesn't matter. when the cylinder bottoms out the relief valve should open and dump fluid back to tank. That's your relief valve pressure. if it's below spec find the relief valve and take it a part there should be spring in inside this spring regulates the opening pressure. If the spring is broken there's your answered. Replace the spring or the entire valve. If the spring is ok time to adjust the valve. Turn the valve adjustment usually CW to increase pressure and CCW to reduce the pressure. Adjust the valve till the pressure comes up to spec. If this doesn't work, on to the pump. If the pump is bypassing internally it won't produce pressure. There are pump testing equipment available which you connect to the pump and it will show pump flow at a given pressure. Most hydraulic shops should have one. If you can't borrow or rent one take the pump apart and check for signs of excessive ware. If there's a lot of ware or scoring. Replace the pump. don't know what kind of pump you have but its probably a gear type they are the most common. If the pump is ok it could be a directional control valve issue. There are spools in the valve which controls the direction of the oil. the spools have o rings that separate each function of the spool, check their condition..
Lastly check the hydraulic cylinders. A cylinder could be bypassing internally. To check for bypassing, extend the cylinder remove the retraction hose and try to extend the cylinder again, if oil flows from the extraction port the cylinder is bypassing. time to rebuild the piston seals.
Think your problem is most likely a relief valve or pump.
Good luck.

 

[SLK001]

Fluid looked dark.

Compared to what? Is anything settling out of the fluid? It could be an o-ring or a seal disintegrating somewhere in the system.

 

[twraska]

In addition to what’s already posted, you need to check the priority valve. Most steering systems have one that feeds oil to the steering and brakes first. If that vale is acting up, you will have perfect steering but little or no hydraulics.