Low hyd fluid Jinma 254

[rkevis]

OK I'm cheap .
I used up a 5gal bucket of Hydraulic fluid and waited till I had problems before I bought a new one.The front loader and three point were slow then the steering started to get hard .I put the Jinma 254 away and got some fluid and filled it up .Now I have no pressure.I checked the filter ,it looks OK.I cracked the intake to the pump and there seems to be fluid there.
I cracked a fitting on the distribution block, fluid is dribbling out there and every 20 seconds there is a pulse, but not enough to power anything.
There is the correct amount of oil in the crankcase (Jerry from Affordable Tractor suggested the front seal in the pump might have popped and pushed fluid there).
Its got to be air locked right?
Help

 

[Soundguy]

Is your crankcase oil real full?

If it did need to be bled.. just leave the line off and let it run..however.. it doesn't sound like the problem if you were saying there was a spurt every 20 sec.. it should have burped air by then.

Any chance you have an intake air leak onthe suction side.. If this model uses an intake filter check for colapse.

Soundguy

 

[RonMar]

The little spurt every few seconds you described sounds like a starved/dry pump. Does yours have a union on the suction line just under the front of the seat(above the strainer)? That is a good place to suck air. Hydraulic pumps are great at making pressure, but not so good at making suction, particularly when they have air in the pump housing. The pump has to build enough suction to pull the fluid up and over the "hump" where the line comes out the top of the resovoir above the strainer. Unfortunately that union is right at the top of the hump and it is far easier to suck air thru a leak than fluid up from the strainer. If you ran it low enough to draw air, you may need to prime it a little. If yours has a union, that is a good place to do it. Separate the union(and while you are at it remove the strainer in the tank and inspect/clean it) and using a funnel and small hose pour fluid down into the pipe leading to the pump. Try and get it as full as you can. This priming of the suction line gives the pump an easy source of fluid to help get the air out of the pump. When you start it up after reconnecting the union, this fluid in the inlet pipe should easilly be drawn into the pump as it is, it will hopefully pull new fluid up and out of the sump to keep the flow established(providing you have no air leaks.

Oh and where did all the fluid go? As mentioned, it can leak into the crankcase thru a bad pump seal, onto the ground thru bad gaskets and plumbing or into the gearbox thru a cracked lower plate. You said you checked the engine oil, have you checked the gearbox level, or do you know where it has leaked from the tractor onto the ground?

 

[3RRL]

I'll bet it's the filter.
You said "it seems Ok" but I'd suggest changing it out new or cleaning the heck out of it. Re-fill with new hydraulic oil then start her up and crank to high rpms. Try the loader first. The spurts could be from a clogged up filter or air in the system. Either way, the clean filter will take care of the clog and the air will purge itself out at high rpms.
That's my guess.

 

[rkevis]

I pulled the pump off and poured fluid directly into it while turning it.
Put it back toether -nothing.
I will try cleaning the filter and priming the line at the union under the seat.
thanks

 

[3RRL]

I pulled the pump off and poured fluid directly into it while turning it.
Put it back toether -nothing.
I will try cleaning the filter and priming the line at the union under the seat.
thanks

Did you test the pump when you had it off? Here's something I posted on another board to test my pump before putting it back on.

But before putting the pump back on, I thought I'd better test in case there was something wrong with it.
Here it is off the tractor.



I took it back to camp and rigged up my drill motor with a rubber hose that I forced over the spline of the pump. Then clamped a shaft in the drill motor and stuck the shaft inside the other end of the rubber hose. I was able to spin the hydraulic motor that way. Then I took a piece of poly pipe and stuck it into the suction hole and a hose on the outlet. Using a bucket full of hydraulic fluid, I was able to test the pump and see that it was working OK. You can see I am working the orange drill motor attached to the motor with one hand and holding the hoses with the other. I thought that was pretty cool.



So I changed the "O" ring and bolted everything back together and fired up the Kama. The hydraulics worked instantly and back to work I went. Life is good again.

 

[rkevis]

I ordered a rebuild kit for the hydraulic pump from Jerry at affordable tractor and in preparation for the project I took off the intake lines.
Just for the **** of it I turned over the tractor and looked in through the intake at the gears of the pump --- they were not turning!
I pulled the pump off and I see some wear on the coupling .
Is there a rubber bushing that transmits the torque?
Where can I get an exploded view?
What is going on ?
thanks
Ray

 

[RonMar]

Ray
Not turning is not good The first link is to John's Jinma site and some closeup pics of a hydraulic pump overhaul. Does the end of your pump input shaft look like the last pic at the bottom of the page? It should have a flat tab on the end that engages a slot in the pump drive gear inside the timing case. With the pump removed, can you see the gears turn when you turn the input shaft by hand? If you can see the gears move when you rotate the shaft by hand, try slipping a small screwdriver or rod into the pump fluid inlet port to keep the gears from rotating, then try and rotate the pump input shaft with a wrench or vise grips gripping the flat/keyed tab end of the shaft(gently, don't apply enough force to break off the piece you have inserted to jam the gears). You should not be able to rotate the pump input shaft with something jamming the pump gears. I am not sure how this pump is assembled, wether it's gears are press fit to the shaft, keyed to the shaft or the shaft/gear are a single machined component. If you can't rotate the pump input shaft with the pump gears jammed, you may have a problem in the forward timing case geartrain.
HydPumpDisassembled

This second link, also courtesy of John's site, shows the timing case parts diagram. The right hand cross section drawing(numbers 31 and higher) shows the pump drive assy. This would be a view from the top looking down or right hand side looking inward of the tractor timing case. The pump mount bolts and input shaft come in from the left of that drawing. You can see that the pump stub shaft engages the pump drive(#34) which is supported by 2 bearings(part# 35 and 39). With the pump removed, stick a large screwdriver into the slotted hole in the back side of the timing case where the pump shaft goes and try and rotate that pump drive. You shouldn't be able to rotate it as it should be hard coupled to the timing gear drivetrain. The most you should be able to do is rattle it back and forth a degree or two(very slightly) as you take up the gear backlash in the drivetrain. If you can rotate it any distance, you have a problem inside the timing case(and most likely gear teeth remnants in the oil pan.
http://www.johnstractor.homestead.com/files/TimingGearFig002.jpg

With what you describe, pump gear teeth not rotating with the engine running, it has to be either the drive gear in the timing case or a bad pump input shaft(sheared or pump gear rotating on the shaft I hope it is the pump...

Good Luck

 

[Ranch_Hand_Supp]

The pump drive gear may have broke ??

https://tommtdplumber.readyhosting.com/secure/ATParts/part_detail.asp?part=TY290X.02.121-1


Ronald
Ranch Hand Supply

 

[rkevis]

I put a screw driver in the intake of the pump and jamed the gears . I was unable to turn the pump with a vice grip on the drive shaft.
I was also unable to turn the drive in the tractor with a screw driver.
It seems to me that the torque is not being transmitted between the tractor and pump.