2840 John Deere Hydraulic Problem

We replaced the hydraulic pump, changed oil, cleaned out screen, the hydraulic filter was collapsed. PTO works good, checked the hydraulic pressure with PTO running, checked the pressure
with the pressure high and low both ways and pressure was high.
At idle speed the steering does not work, nor hydraulics or 3
point.
Any help and ideas what to do next would be greatly appreciated.
Thanks!
Chad

Welcome to YT
Hyd filter collapse isn't a very good sign. What was wrong with the hyd pump that was replaced? Do hyd's operate the same with hyd hi-lo in either speed? Have you tried operating hyd's with steering supply line capped off? Have you looked in hyd filler hole behind seat for moving oil when engine is running/3 pt in raised position?

You are loosing charge oil pressure, a common issue with these, you can spend WEEKS
LOOKING and working to correct it, if your not in love with it I would trade it and
go on

HI
Thank you for your input, I do appreciate it. Where is the most common place you would lose the charge pressure? The tractor has under 2500 hours. We have not capped the steering line yet.
Thanks
Chad

(quoted from post at 09:57:55 09/11/16) HI
Where is the most common place you would lose the charge pressure? Chad

Click to expand...

Supply tubes for hyd hi-lo & pto have a history of failure. As I previously stated check inside hyd filler hole for moving oil.

Thank you I will do that today. I appreciate your insight.

I had a long response written but the filters on here would not let it post. WHY??? I do not know. after fooling with it for over an hour I gave up.

So here is the simple response and it is like TimS post. IF your not too deep money wise in this tractor SELL it ASAP!!!! A JD 2840 with hydraulic issues is a "MONEY PIT"to fix!!! I do mean money pit with capitals too. LOL You could easily spend $5-10K fixing it. Even then you may still have troubles not far down the road.

It seems like once these tractors have some age on them and start to have hydraulic issues they never are 100% "FIXED".

So my recommendation is to RUN and run fast!!!

Here is my long response. LOL Maybe

Well the hydraulic filter collapsed tells me you have a load of junk/metal/brake material in the hydraulic sump. Why did you replace the hydraulic pump???? A collapsed filter is trouble in the rear end section of the tractor not the front hydraulic pump. Have you checked the sump screen??? Is the sump screen what your calling the hydraulic filter???


Now after all these questions. Since you have run the tractor with the collapsed screen/filter you have contaminated material throughout the entire hydraulic system. To fix it to where you know it will work 100% of the time is quite a costly endeavor and you need to be real familiar with the JD 2840 hydraulic system. There is a reason the resale value of a JD 2840 and JD 2940 is low it is the cost of hydraulic repairs when they have a major failure. The cost can easily be $5K and up just for parts. I did a JD 2840 ten years ago with problems like your and it cost over $10K to get everything fixed. I told the owner the tractor was not worth it but he wanted to repair it.

With that stated If you want to try to repair your going to need to do some checking before throwing parts at it.

1) Drain all the oil and remove the sump screen and check for contaminated material in the rear end hydraulic sump/housing.

2) If you do not find much on the way of contaminated material then reinstall the hydraulic oil and run the tractor with a pressure gauge in the charge pump circuit before the main pump. I do not remember the exact pressure you should have but it is around 150-165 psi. If you do not have that then there are several thing s that could be wrong and they all are in the rear of the tractor.
a) The charge/transmission pump has failed.
b) One of the internal lines has broken.
c) The seals in the PTO or Hi/Lo/ clutch packs have failed.
Any of these three will dump the charge pump oil back into the rear sump causing the front pump to starve for oil.


Post back if you try these things. I could write a book here trying to "guess" what your troubles are on a JD 2840 hydraulic system. They are a nightmare to keep working once they messed up. The only way I ever found to be sure of a hydraulic repair on them was to go thorough the complete system front to back at one time. Doing one thing and running it just move contaminated material around an you will never get it fixed.

I wish you luck. Truthfully if your not too deep in the tractor money wise I would sell it and buy something else. These can be a total money PIT!!! The only good thing about them was the 329 motor. It is a great motor. I have seen them used in repowering a JD 3020 gas and that works great.

HI
Ok I just checked the filler hole behind the seat and there is no moving oil with 3 point up.
We idled up the tractor and got hydraulic pressure and then brought tractor back down to idle. PTO on-off, 3 point up or down, hi-low either way made no difference in
hydraulic pressure but when I turn the steering wheel it lost all pressure, I throttled it back up and pressure came back, it held for awhile and lost pressure again
without moving steering wheel but if I throttle it up the pressure always comes back. Took hydraulic filter off, cranked tractor over and got plenty of oil coming out.
We also put a low viscosity oil in it because of the cold weather where we live. The PTO should be good because it runs a snow blower under load and never gives me
any problems.
Thanks for the help
Chad

Sounds as if steering valve is leaking. Cap steering supply line the operate a little while so see if hyd's operate correctly.

JD Seller, can you email me in regards to your comment on 3020 gas re-powering with the 329 diesel? I would like to know more about that. thank you