New Jinma 284 Owner with Hydraulic Pump Pressure Question
quicksandfarmer
Elite Member
The way most Jinma's are plumbed it's very easy to tee in a hydraulic gauge. The output from the hydraulic pump goes directly to a quick-disconnect that feeds the loader valve. You just make up a tee with a male QD on one side and a female on the other and the gauge on the third leg of the tee and stick it in that first QD. Should be less than $50 in parts from Northern Tool or Surplus Center for the whole thing. Use hydraulic fittings, plumbing fittings will explode under the pressure.
If the pressure is insufficient there are three possibilities: the flow is obstructed (dirty filter, low fluid), the pressure relief is going off too low somewhere (you would hear it) or the pump needs to be replaced. I wouldn't suspect the pump until the other possibilities were exhausted. Clogged filters in particular are very common on these tractors.
If the pressure is insufficient there are three possibilities: the flow is obstructed (dirty filter, low fluid), the pressure relief is going off too low somewhere (you would hear it) or the pump needs to be replaced. I wouldn't suspect the pump until the other possibilities were exhausted. Clogged filters in particular are very common on these tractors.
RonMar
Elite Member
I also wouldn't throw too much hydraulic tech time/money at it. A stock replacement pump is between $179-$189 depending on the engine you have($230 for a higher output upgrade pump) on Affordables website https://affordabletractorsalesco.co...ategory=Hydraulic Pumps&category=Parts Center.
When a hydraulic pump costs you $5K+, yes, a little tech time for a flow study may be justified before swapping a pump. At this level, some educated pressure analysis is usually sufficient
Like quicksand mentioned, the easiest way to squelch a pump output is to starve it's input for oil. So if you are sure you are not sucking air and the suction strainer in the sump(or in the suction line in later models) is not clogged. Another way to fairly easilly test the suction line is to disconnect it at the pump, put a bucket under it and apply a little air pressure to the vent port on the reservoir fill plug. The suction port on the pump an a 284 is lower than the fluid level in the reservoir, so the fluid should start to flow as soon as you crack the pump suction fitting, and if left to set and drain should easilly drain most of the reservoir. Adding a little air to the vent port and the fluid should flow rather quickly...
I believe your troubleshooting is sound(same lower than relief pressure from 2 different loads). From the info you provided, i think it is your pump.
You said it had a suction side leak when you got it? It could have been that it was sucking air a long time. Air going thru a hydraulic pump causes cavitation and added noise. The cavitation will cause premature wear and ultimate leakback on a hydraulic pump. It also causes them to make a significant ammount of added noise under load compared to a pump that isn't pumping air along with the fluid, which is a giveaway when you know what to listen for. It helps to have another pump around to compare to... "Hey how come that one is so much noisier" Your difficulty reaching rated output pressure with no flow/noise thru the relief valves is symptomatic of a warn out pump...
When a hydraulic pump costs you $5K+, yes, a little tech time for a flow study may be justified before swapping a pump. At this level, some educated pressure analysis is usually sufficient
Like quicksand mentioned, the easiest way to squelch a pump output is to starve it's input for oil. So if you are sure you are not sucking air and the suction strainer in the sump(or in the suction line in later models) is not clogged. Another way to fairly easilly test the suction line is to disconnect it at the pump, put a bucket under it and apply a little air pressure to the vent port on the reservoir fill plug. The suction port on the pump an a 284 is lower than the fluid level in the reservoir, so the fluid should start to flow as soon as you crack the pump suction fitting, and if left to set and drain should easilly drain most of the reservoir. Adding a little air to the vent port and the fluid should flow rather quickly...
I believe your troubleshooting is sound(same lower than relief pressure from 2 different loads). From the info you provided, i think it is your pump.
You said it had a suction side leak when you got it? It could have been that it was sucking air a long time. Air going thru a hydraulic pump causes cavitation and added noise. The cavitation will cause premature wear and ultimate leakback on a hydraulic pump. It also causes them to make a significant ammount of added noise under load compared to a pump that isn't pumping air along with the fluid, which is a giveaway when you know what to listen for. It helps to have another pump around to compare to... "Hey how come that one is so much noisier" Your difficulty reaching rated output pressure with no flow/noise thru the relief valves is symptomatic of a warn out pump...
Affordable
Advertiser, Platinum Member
When you do take your pump off also inspect the pump driver, it could be worn and also causing you problems. If you will send us a pic of the end of your pump ( shaft) and the pump driver we should be able to tell you if it needs replacing
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
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
Thanks for the info I am sure it is the pump also and it is a reasonable price vs other cost to test more. Do not know how long suction leak was going on (was there when I purchased it) but I think it was for a while from the way the seller was talking ( gave me 5 gallons of the wrong fluid with the tractor lol). Seller was using Tran/ hydraulic fluid in unit ( now AW32). Had suction line all apart and it is clear along with new filter so I feel confident that pump is getting what it needs. Anyway think I will use it at this low power for this season and plan on replacing next winter when I do full maintenance. One question about pipe fittings the QD have been replaced with 1/2 pipe couplings is this something I need to take care of?
Bob Rooks
Elite Member
Make sure they are schedule 80 pipe couplers or high pressure steel fittings.
RonMar
Elite Member
Like Bob says, as long as they are high pressure rated piping, they should be fine. The only reason to have QC's at the loader is if you plan on regularly removing your loader. IF not, straight thru high pressure pipe fittings are probably better as an inadvertyently/accidently disconnected QC connection CAN kill a hydraulic pump. The hydraulic systems on these tractors are known as "open center" That means that the fluid ALWAYS flows, either thru the system unloaded, diverted to a loaded cylinder and moving that and returning from the other side of the moving cylinders, or thru the safety relief when the cylinders reach max load or their physical limits. THE FLUID MUST ALWAYS FLOW... When you pop a QC, the fluid stops. That is when pump bodies, hoses, seals and pipes blow, drive shafts twist, drive gears crack ect
RonMar
Elite Member
When you say new filter, did yours have a spin-on cartridge on the suction line? IF so, that was a strainer cartridge(#100 mesh/150 micron). If you replaced it, you need to make sure it was with a cartridge designed for a suction side application. If not specifically designed for a suction side application, it can cause flow issues as it is too restrictive to allow fluid to be easilly sucked thru it, starving the pump for oil...
There is a whole school of thought on the merrits(or lack of) of using a filter/strainer on the suction side of a hydraulic system. If the reservoir is clean, the vent has a screen filter with restrictor and dessicant to cut down on "breathing" and condensation and you only add clean fluid thru a strainer, the fluid feeding the system should be clean. It is probably of greater value to have a small bore filter(10 micron) on the return to the tank... The fine metal and debris that can be returned to the tank are too fine to be caught by the less restrictive suction strainer and can if stirred up be drawn back thru the pump despite the strainer's presence...
Yes have the 150micron in line to the pump. Clearly had good flow in that on restart had line open right after the pump into 5 gal bucket and to was pumping well. If I want the 10micron filter I assume I would put into the return line after diverter valve which over time would get most of the oil but not the oil going to the 3pt? Also any worries about pressure for that unit or is it just a standard filter with a bypass?
SPIKER
Elite Member
One more thing to check since you said they have removed the QDs from the FEL then perhaps they may have also installed a Pump HP Bypas (relief valve) between the two pump (suction and pressure) lines>?
It is a Mod done by more than a few people to prevent inadvertent pump damage should a QD come apart the fluid would circulate from pressure side thru the new valve and back to the suction side.
Damage to suction strainer can lead to the pump shaft end seal leaking air (sucking bubbles into pump) as it can't get enough fluid into it.
Mark
It is a Mod done by more than a few people to prevent inadvertent pump damage should a QD come apart the fluid would circulate from pressure side thru the new valve and back to the suction side.
Damage to suction strainer can lead to the pump shaft end seal leaking air (sucking bubbles into pump) as it can't get enough fluid into it.
Mark
