Erratic and jerky hydraulics

[pcolyer4]

Hello everyone. I bought a used Jinma 254-2 (all I could afford) and the previous owner said it blew a hydraulic hose and he replaced it and since the hydraulics are erratic and jerky for the FEL and 3-point. I assumed he had burned up the pump so I replaced it and all the hydraulic fluid and it's doing the same exact thing as it was, you must raise the rpm's and the raise and curl functions are jerky like there's air in it. Does anyone know what may be causing this? It supposedly worked smoothly as it should before the hose blew! Thank you in advance.
Paul

 

[repete]

Which hose did the previous owner replace?

 

[pcolyer4]

I think it was to raise bucket but not 100%

 

[Mike1955]

Pro I assume this issues is resolved. I was going to point out the only time I ever had that problem was that it was due to air in the lines. Fix it by keep operating it

 

[Fred in BC]

As Mike said, it sounds like air in the lines.
If there's air in the system when you fill the reservoir, it may take a while to work out of the system.
Go to full lift on the loader, then all the way back down. Check and fill the hydraulic oil.
Run the 3 point full up and full down several times. Same with anything else hydraulic. If things run a little smoother, you know you're on the right track.

 

[RayIN]

As Mike said, it sounds like air in the lines.
If there's air in the system when you fill the reservoir, it may take a while to work out of the system.
Go to full lift on the loader, then all the way back down. Check and fill the hydraulic oil.
Run the 3 point full up and full down several times. Same with anything else hydraulic. If things run a little smoother, you know you're on the right track.

Yep, operate all cylinders, both ways to full-stop, while never allowing hyd, oil level to fall to the add mark.

 

[pcolyer4]

I'm sorry for not responding, I never received any replies until all at once days later. I have been running all the functions of fel, 3-point and steering and the problem hasn't gotten any better. Someone had said about the quick connections and they may be causing this and another suggests putting a gauge immediately after the pump to assure it's working properly even though it is new but it's doing the same thing as when I got it and I just assumed he may have inadvertently burned it up after blowing the hose but he assured me it was operating normally before the line blew...

 

[oldnslo]

Triple check all of connections on the inlet line to the pump to confirm they are tight and not leaking any air when under vacuum. If there is a rubber hose on the pump inlet check that for cracks or if soft and collapsing under vacuum.

 

[pcolyer4]

Hello and thank you for your reply. When you say inlet do you mean the suction side of the pump going from the filter/reservoir to the pump with a rubber hose and 2 hose clamps? Or the pressure side going to the distribution manifold which I believe holds the pressure relief valve?

 

[pcolyer4]

This pic is from the pressure side and has a smaller hose?

 

[oldnslo]

Suction side with hose clamps is where air can be drawn in. Check to see if the hose has hardened or cracked with age. Also check to see if soft and spongy from age. make sure clamps are tight.

 

[bowenskye]

Does it have a variable displacement pump?
If so, you may need to check, and adjust the pilot pressure.

 

[MH8675309]

I recently had the same issue and it was the pickup screen in the bottom of the hydraulic oil reservoir. All the oil had to be drained out - get at least 4 clean plastic 3 gallon pails - or more depending on how much it holds - to catch this. My screen was covered and I mean covered in what looked like wood shavings from a chain saw. Carefully scraped it off with a chisel and then sprayed it thoroughly with brake clean and then blew it out with an air hose. Put it back in filled it back up with the same fluid and working normally again. An easy fix. Start with the simple / cheap stuff first

 

[piper184]

Most likely on the 254 (same as my 284) the tank screen comes out of the top of the tank. It will be held in with 3 bolts and located under the front left corner of the seat.
Remove the suction line that leads to the pump and unbolt the cover. The screen is at the end of a pickup tube that is mounted to the cover.
Removed, clean and inspect. Also probably a good idea to put a magnet on a stick and "fish around" at the bottom of the tank in case there are any metal bits.
You may or may not need to replace the cover gasket. If you don't have ready access to one they are easy to cut out of gasket paper, or as the last resort, use RTV.

There are two relieve valves in your system. One in the loader control valve, this holds pressure to operate the loader. The other is in the 3 point valve assembly. This provides pressure to operate the 3 point and the steering. Valves can get loose or get debris in them but are usually trouble free.

The OEM quick connects that allow you to remove the loader are a known source of issues. Usually they pop loose when you don't want them to and dead head the pump. This usually blows the front seal of the pump and puts all the hydraulic fluid into the engine crankcase. However, they are also know for having low or poor flow. Replacing them with quality made connectors is easy and not too expensive.

Are you having the issue on level ground or only when you are pushing a pile and the front is significantly higher than the rear? I have this happen when I am piling material and the fluid level starts to get low. Since the pickup tube is in the front of the tank, it will sometimes uncover and suck air if I am pointing uphill. IMHO that is one of the downfalls of this tractor series is that the sump is too small for loader work. It is fine for the base tractor running power steering and the 3 point.

This is assuming that you do not have the separate power steering system. Some of the early years used two systems.

 

[pcolyer4]

Thank you for your great instructions and although the pickup screen was clean, it did lead me to looking at the suction side instead of the pressure side and I found the lud wasn't sealing when tightened down at the reservoir therefore it was sucking air! Working great now as it should! This is a great site and everyone has been very helpful! Back in business!!!

 

[pcolyer4]

Hello everyone. I bought a used Jinma 254-2 (all I could afford) and the previous owner said it blew a hydraulic hose and he replaced it and since the hydraulics are erratic and jerky for the FEL and 3-point. I assumed he had burned up the pump so I replaced it and all the hydraulic fluid and it's doing the same exact thing as it was, you must raise the rpm's and the raise and curl functions are jerky like there's air in it. Does anyone know what may be causing this? It supposedly worked smoothly as it should before the hose blew! Thank you in advance.
Paul

I wanted to thank EVERYONE for their helpful thoughts and instructions. The hydraulics are working smoothly, just as intended! I was focused on the pressure side but it was pulling air into the suction side causing all my problems! Thanks again everyone!

 

[eco88]

I was going to say, is it a kioti??
Mine has been doing that since brand new. Backhoe especially can be extremely difficult to maneuver

 

[Fred in BC]

A faulty pressure relief valve could make the system jerky.
I've never seen that, but I'm sure there's lots I've never seen.

 

[Fred in BC]

Glad you found the problem!