Jinma 284 3 point won't stay up

Dre0256 · Nov 25, 2018

Hello all. Am new here, 1st post. I have a Jinma 284 that I just purchased a few weeks ago. I got it cheap knowing it had some issues. The main issue is the 3 point hitch slowly goes down on its own. I've already searched and read before posting. Seems like the piston may need new o-rings (rebuild kit). My main question is, if so I need a how to or step by step on how to remove the piston so I can change the o-rings. I saw that there might be two types of piston I guess. Type 1 and type 2 (less common) how do I know which one I need? Thank you for any and all help.
Dre

quicksandfarmer · Nov 25, 2018

There are at least three types of Jinma lift boxes so you need to figure out what kind you have. Does it have any identifying marks or numbers? It might help to post a picture.

I've done the seal replacement on my tractor and it wasn't a big job. The hardest part was figuring out how the piston came out, it can be either toward the front or the back, or up. The plate that held the piston in was just four bolts, although they were on super tight, I needed a big breaker bar. The piston isn't connected to anything. On mine there was a 6mm threaded hole in the piston, to remove it I screwed in a 6mm bolt with a piece of plumbing strap on it and pulled it out with pliers.

What I don't remember is whether I had to drain the hydraulic fluid, I'm thinking not.

Usually the piston seal fails when the piston travels too far and the seal goes out over the edge of the cylinder while under pressure, blowing it out. So after you replace the seal you have to adjust the piston travel.

Dre0256 · Nov 25, 2018

Dre0256 · Nov 25, 2018

Also the one picture am pointing to, it had plastic wrapped around it. Should there be a cap or breather there?

quicksandfarmer · Nov 25, 2018

The plastic wrapped opening is the hydraulic fluid fill point. It should have a cap with a dipstick.
This one: 3.55.41 ( Oil Dipstick Assembly for hydraulic reservoir ) | Jinma Tractor Parts, Farm Pro Tractor Parts | Circle G Tractor Parts

It looks like your lift box is the same as mine. I have the 300HY lift box, the name is cast into the side.

The lift cylinder comes out toward the steering wheel. You have to disconnect the pipe going to the rear single remote, and then there are four bolts that hold the front plate on. In order to get at those four bolts you have to take the top cover off of the gearbox, six bolts. (The gearshift lever is in the way). Make sure the top of the gearbox is clean before taking it off so you don't drop crud in the gearbox. The four bolts are on very tight. They cylinder and piston come out together,

To get the piston out of the cylinder there is a 6mm tapped hole in the back of the piston. I put a 6mm bolt through a piece of plumbing strap and fastened it, and then pulled it out with pliers.

You may have to heat the seals to get them flexible enough to get them on the piston. To do that, boil some water in a pan on the stove. Put some hydraulic fluid with the seals in a container and dunk it in the boiling water.

Dre0256 · Nov 25, 2018

Great information, thanks a lot. Couple more questions. Am good with most everything except the pipe to the rear single remote. Also do you know which rebuild kit I need? I saw two and want to make sure. Again thank you so much.

quicksandfarmer · Nov 25, 2018

Dre0256 said:
Great information, thanks a lot. Couple more questions. Am good with most everything except the pipe to the rear single remote.

In your third picture there is a shiny pipe that comes off of the plate you have to take off to get at the cylinder. It's held on with a single bolt through the round end. You need to take that bolt off to get the pipe off. That pipe goes to a rear hydraulic remote hookup that you can use for a dumping trailer. It may leak a couple teaspoons of oil when you take it off.

Dre0256 said:
Also do you know which rebuild kit I need? I saw two and want to make sure. Again thank you so much.

I don't know which kit you use. I would look for a model number on the lift box. There are several companies that sell Chinese tractor parts over the Internet, they are usually helpful and knowledgeable. Tommy from Affordable Tractor Sales often posts here. His website is: Home of compact Jinma, Foton, and Koyker Tractors and Parts, Wood Chippers, Backhoes - Affordable Tractor Sales Company