New Jinma 284 Owner with Hydraulic Pump Pressure Question

[OccDave]

Hi

Just purchased a 284 Jinma and am trying to get it running well. Currently got the 3pt lift working and fixed a suction leak. All is working but appears that the pump(?) is not producing a lot of pressure. Currently hydraulic line goes from pump to 3000psi pressure gauge T before going in to FEL valve. Line then leaves FEL valve and goes to diverter valve which feeds power steering, 3pt, and pressure relief to reservoir. If I stall out FEL pressure only goes to 1000-1200psi (also stalling out 3pt produces same results). Do I need an new pump? Is there a rebuilt kit for these pumps that will fix this problem? Or should I look at something else? It was my understanding pump should produce around 2200psi is this correct?

 

[Affordable]

The pumps will produce more than 2,200 PSI, we set the relief valves on the loaders at 2,200 PSI,With the gauge inline you should be able to get the frontend loader to go upp to at least the 2200 PSI before relieving, so you could have a weak pump.Most of the time a weak pump will not rebuild as its a alumin. body and the body has possibly worn allowing the fluid to bypass. We have the pump rebuild kits as well as new pumps.

Tommy
Affordable Tractor Sales
"Your Jinma Parts Superstore"
Home of compact Jinma, Foton, and Koyker Tractors and Parts, Wood Chippers, Backhoes - Affordable Tractor Sales Company

 

[J_J]

If you have crud in your relief valve, you might be bleeding off fluid.

It would be best if you had a flow and pressure test.

That will put a load on the hyd system using a different relief valve, and the results will tell you if the pump is putting out the advertised pressure and volume.

 

[OccDave]

Sounds like I need a new pump. Not sure how I could test if more in that I get the same pressure readings when I use the FEL and the 3pt and the FEL is before going into the diverter valve. I guess both the FEL and Diverter relief systems could be bad? Not sure how I could test these without spending more than the pump cost but maybe I am missing something?

 

[RonMar]

Yep, as long as you are sure you fixed the suction side leak, it sounds like a pump issue, as you were using 2 different relief valves there. When you load/deadhead the loader, the loader relief would be relieving downstream to the rest of the system. When you were loading up the 3PH, that should have been causing the relief back in the 3PH valve to relieve. Since they are two separate valves, I would have expected 2 slightly different pressure readings from the two different reliefs. Since you got the same 1000-1200 PSI with both tests, it looks to me like the pump is bypassing internally. Another way to confirm this is with a mechanics stethescope listening on the relief valve assembly on the loader valve. When you deadhead the loader, if the relief is opening, you will hear the woosh of fluid thru the relief valve. IF the pump is bypassing internally, you won't get the woosh at the relief.

The 3PH control valve relief is under the square headed plug on the top forward part of the valve block. It has a valve plunger, a spring and a couple of stacked washers. The number of washers used sets the relief pressure. My 284 3PH valve was delivered with that relief set in excess of 3000 PSI. I had to remove one washer and grind a little off another to get the pressure down around 2200PSI. When you get a new pump on, I would expect you to see different relief pressures between loader and 3PH. You can also deadhead the 3PH real easilly by closing the speed reg valve located down in front of the seat. It is a round water faucet looking valve control used to slow the lowering of a heavy impliment. IF you screw it all the way closed, it will stop fluid from entering the 3PH cylinder completely, which causes the 3PH valve to go into relief immediatly upon activating the control.

Since you are having pressure issues and they appear to be at the pump, keep a close eye on your engine oil level. These pumps sometimes relieve themselves thru the front seal and case which is bolted to the rear of the accesory drive case, This leaked hydraulic oil will add itself to the engine oil

 

[SPIKER]

OCCDave:

Pumps like these do not produce PRESSURE they make FLOW. Pressure is resistance to flow. They will produce LOTS of pressure right up til they blow the sides out of the pumps...

NEVER disconnect any of the FEL lines or QDs with the engine running you will blow up the pump. Some times you blow the end seals or plate seals but most often ruptures side of pump.

Most of us with QDs in the FEL lines will put Zip Ties around the coupling slider so they can't disconnect by brush or accident.


With something (FEL or 3PT) tryign to lift something too heavy you will see Pressure on the gauge that is "T" teed into the lines. It will only rise (using FEL) and too much weight in it up to the point the Relief Valve on the FEL opens. It is adjustable by a small screw driver and locking nut under the valve cap on the end plate of the Valve. Must remove the cap, then loosen lock nut and turn the screw IN for more pressure. DON'T ADJUST MORE THAN 2200PSI, FEL Damage or Blown lines broken front end parts or nosing over the tractor can happen.

Doing the same with the 3PT, it should only see about 1800~1900 PSI under normal adjustment. If it goes to same max pressure as the FEL (~2200PSI) then the FEL relieve valve is letting the pressure thru it and the 3pt valve is turned in too much or is sticking...

Mark

 

[RonMar]

Mark
On the way the Jinma 284 is typically configured, the FEL only has an inlet and an outlet line/port, so the FEL relief vents excess pressure caused by the load on the loader into the outlet line and sends it downstream to the steering and 3PH. When you load the 3PH, the FEL relief valve can have no effect on that pressure as both the inlet and outlet lines on the FEL valve see full system pressure applied by the 3PH. A relief only works if it has a low pressure path to relieve the pressure to. The FEL valve's 2 ports are in the stream and it has no place(third hose/return port) to vent the excess pressure to...

 

[J_J]

Just have a hyd tech do a pressure and flow test. About $60, and 30 min if he has all the adapters.

https://www.youtube.com/watch?v=78fByIQ5D40

Well laid out test bench at hyd training lab.

https://www.youtube.com/watch?v=FjmR0DyAoTA

I believe you should be looking at 75 % of no load to full load.

So if the pmp produces 20 GPM at no load, then your min at full load should be at least 15 GPM. More is good.

 

[OccDave]

Yes my FEL only has two ports (in and out) the outlet port then flows to the diverter valve which then runs to the power steering; the 3PT; along with relief line to the sump. As such it appears to me unless I have two bad relief values (FEL and diverter/3pt) set to the same low setting (1200psi) I must have a bad pump. I a very sure I have fixed the suction leak in that before fluid was blowing out the sump vent hole and clearly had air in it. Currently no blow by the vent and hydraulic fluid looks great even after many hours of work. I will try to find someone around hear that can do a flow and pressure test at a reasonable rate but this being wine country in Calif $60 seem very unlikely. Also finding someone that has the fittings that will tie into the Jinma may be a problem.

 

[J_J]

How close is a hyd shop that you can trailer your tractor over to the shop.

He should have all the parts to connect.