2840 Hydraulic problem

tjhunter61

New member
I just picked up a 2840 John Deere. Runs great but the three point lift jerks and jumps when raising. I am new to this type of tractor and have no manuals for troubleshooting help. My questions are: Where is the hydraulic filter located? Does anyone have any troubleshooting ideas? The three point hitch seems a little weak to me as well and 'bleeds' down when the tractor is not running. I appreciate any help anyone can provide!!
 

Doc

Admin
Staff member
Gold Site Supporter
Hi TJ, and welcome to Net Tractor Talk.

Congrats on the new tractor. Can't help with the filter, but would recommend you find a place that has a manual you can buy.

As for the 3PH jerks and jumps, have you checked the fluid levels? You probably want to change out the hydraulic fluids. I recommend the synthetic types as I've had great results with it. Stuff leaking down when engine is off is not unusual. It is good practice to always lower all implements so as to take all pressure off the hydraulic lines when you shut down the tractor. Pressure over time will cause leaks in the lines. if it is a fast leak down you have a leak somewhere that you will have to find and fix.
 

tjhunter61

New member
Thanks Doc...seems like a bunch of good people here and I appreciate your reply! It only has a small leak where the hitch arm connects to tractor (seals) Not bad though. I've found a couple of manuals and will order one asap. I wanted to change the Hydraulic oil first thing but am not sure where the filter is located so I'll have to wait for some help...or a good manual! Thanks again!

TJ
 

jd110

Member
The transmission/hydraulic filter is under the right hand side of the transmission. It is a cannister style filter that you need a 3/4" wrench to remove. The cover is #2 in the diagram and the filter element is #7. There may or may not have a hydraulic line connected where plug #1 is in the diagram depending on how your tractor is equipped. There is also a sump screen just behind the filter in the side of the transmission. It has a plug about 2 inches across that you screw out with a 1/2" drive ratchet or breaker bar. You do need to drain all the oil before removing the sump screen.
 

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tjhunter61

New member
Big thanks back to you jd...I really appreciate it. I thought that might be where it was but having never serviced one of these I figured it would be my luck I'd open it up and spring/balls/miscellaneous pieces would come flying out and I'd never get back together! While I got ya though...is there a convenient place to drain the oil? And is there any possibility that bad oil...dirty filter...plugged screen is causing the jerking motion in the lift...or am I in for major repair work? Again, I really appreciate the support!
 

jd110

Member
The drain plug is at the bottom of the housing on the right side. It is near where the right side draft arm for the three point is attached to the transmission housing. You will need a 1 1/8" wrench. The filters and oil is definitely where you want to start. It can absoultely be your problem, but there are other things that can be wrong also. Since your three point leaks down(how quickly?), it is likely it needs new orings and seals installed in the valve and cylinder. The steering valve could also have blown orings that leak internally and rob the system of oil flow. Also transmission hi-lo(rabbit and turtle lever on left side of steering wheel) or pto clutch can have internal leaks, hydraulic filter relief valve can be bad, transmission pump or main hydraulic pump may be worn. Try starting the tractor and leave it sit for maybe 15 minutes. Then try feeling all the hydraulic components to see if anything is hot. Heat build up indicates an internal leak.
 

tjhunter61

New member
Wow...great reply...I really appreciate the help! I will start the tractor and check for heat like you said...I am going to service the tractor next week so that will tell me if its a filter/strainer issue. I would guess its more likely some valve leakby issue and I'll have to fix one at a time until it straightens out...or I run out of money! Thanks again for the advice!
 

tjhunter61

New member
working on this right now...found filter completely collapsed (not a good sign huh). Oil looks like it has water in it (milky/coffee color) and I haven't pulled the screen out yet. Any trick to pulling that screen out? thanks for all the help guys!
 

tjhunter61

New member
Ok...hydraulic oil has been changed...tranny/hydraulic filter changed...screen cleaned...still jerking and jumping :-( With the engine revved up to about 3/4 throttle it will operate smoothly but anything below that and it jumps like crazy. Anyone have any suggestions on how to check anything else that might be the problem?
 

Doc

Admin
Staff member
Gold Site Supporter
Man, that's a tough one.
Are you saying the engine runs smoothly but when you try to move the tractor jumps, or does the engine jump/ miss also? Do all your other hydro parts work okay such as FIL, rear implements up and down, or do they jump also when below 3/4 throttle.
What RPM is 3/4 throttle?
If possible a video w/ sound might help diagnose this issue.
 

tjhunter61

New member
Doc, it's just the 3pt lift that is rattling and jerking as its raised. I don't have a FEL and I can sometimes feel a little 'jerkiness' in the steering but not always. It only does it at half throttle or lower...if the engine is 'revved up' to 3/4 throttle the lift works smoothly. I just don't know how to determine if its the pump or another component that needs repair. I will look into posting a video...unfortunately I am almost as challenged with computer technology as I am with repairing tractors!! Thanks for any advice...I appreciate the time and effort!
 

Doc

Admin
Staff member
Gold Site Supporter
Sorry for my confused. Post, I thought I was in another thread.

More details like you gave will help someone come up with an idea or two. I am not a mechanic either, but from the sounds of things it seems the unit is started which would mean something plugging the line or weak pump.

good luck getting to the bottom of this.
 
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