4020 hydraulics wont hold

been baling with my nh 847 and cant seem to keep the tailgate latched when the balr gets nearly full itvforces the gate open ,,.the latches are always lokt when I start making a bale and the twin hydraulic rams pulls the latches to home position on the baler correctly ,,. the tail gate lifts easily and stays in all up position or mid ways ,.. so I doubit if the twin rams are leaking internally .. is ther e a valve anywhere on my 4020 that is releasing on its own ?

The scv on the tractor is leaking internally. They can be rebuilt.

Latch the gate closed and flip the levers under the SCY couplers to close the circuit. Bale a bale. If the gate stays close then the baler is OK. It is more than likely the tractors SCV valve leaking off under load. You do not say if your 4020 is a side console or dash control SCV tractor. It makes a difference where the SCV value is located.

I'll add to the other replies that you could also swap hoses from one side of breakaway coupler to other side. This will reverse control lever operation but might keep tailgate closed.

Thanx Tex JIm, yes ,already tried that , gonna try,jd Sellers suggestion next ,, still got a waterway that ought to yield at least 2 bales .. how tuf is the svc to rebuild and repair ,.. ?

(quoted from post at 06:36:32 07/20/15) Thanx Tex JIm, yes ,already tried that , gonna try,jd Sellers suggestion next ,, still got a waterway that ought to yield at least 2 bales .. how tuf is the svc to rebuild and repair ,.. ?

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There are 2 pressure & 2 return poppet valves that must have their clearances set in the thousands of an inch. What is your tractors age or serial number? Valve bodies are different from early to late models.

What year is it??

just got off the phone with my local trusty Deere service rep ,,. he told me same sorta thing and more .. I was thinkin of fixing it myself , mine is a nice 1966 , that always seems to know when I have a couple thousand bux I could spend. ... seems far too complicated for a guy that field fixes Case tractors ,,. not a simple component repair done at the shop and then bolt on , and it always worx ,.,, no way of testing off the tractor, to get optimum performance of the hydraulics ,durn the luck ,. I just resurrected this power shift 4020 after being down 4 yrs .. was down with a bad injector pump and starter troubles ... doubtful if changing 4 yr old fluid would make the problem go away,,i have been changing hydro fluid and filters at least once a yr, but have not changed it out yet ,, still has good pressure on the pshift guage .. I suspect it has a pc of the brakes in there somewhere .. the brakes were replaced after they polluted the system some 6 yrs ago,,. Deere folx did all they could to clean up the tranny including leaving a magnet in the tranny to collect the fragments ... tempted to take it apart and clean ,, but am told it may leak too bad after, IF ?? a failed attempt by me to shop repair .. Then I wont be able to drive it up on trailer to take to Deere...anyway gonna try baling with out the hoses hookt up before it rains here in ...a couple hours... mite be cheaper if it were the New Holland balers fault.. but their parts are getting pricey Now TOO .I like this tractor . but am having horrible expensive luck,, if you knew the entire list of all I have been thru with this ol gal over the last 25 yrs , one mite understand why I am partial to the crude and primitive , yet simple Case ..

The early ones with the dash hydraulics are tough to repair, I can re-build and bench test the newer 4020 SCV's that are on the console models, but not the early ones,, your cheapest way to deal with this is to get a used one from a salvage yard,,you may get it to work out if you just reverse the hoses at the coupler, leakage may be just in one direction..

well ... the Deere mite be alrite , afterall ,, that's a relief because they said they are a week out with them lined up, and it was not gonna be cheap ..// I unplugged the hydraulics and the baler and built another bale,,, durn thang!. still unlatched itself when the bale got to 90 percent or so ,,. now, I am thinkin there is air in the lines and gonna try purging the air from the twin cylinders on the nh 847 ... but 1st gonna eat sumthin.. LOL

(quoted from post at 13:01:12 07/20/15) still unlatched itself when the bale got to 90 percent or so ,,. now, I am thinkin there is air in the lines and gonna try purging the air from the twin cylinders on the nh 847 ... but 1st gonna eat sumthin.. LOL

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How do you think air can get into a sealed cylinder? I think one or both of your balers hyd cylinders have piston packing failure.

no ,, got to thinkin,.. I think I caused this on myself /// when I had the baler on the 730 case and I bled the lines out for single power up only ,,. because the 730 don't like to power down and lock ,, ( another thang I need to fix ) I suppose there was still air somewhere.. I cycled the lid serveral times at full throttle ,,, made one bale ,no trouble ,. we are on a roll!!! had nearly another bale and of all things ,,,.busted a u joint ,, gonna fix it and try again ,,, up side is the rain held off and i was able to rake up more... I thought it was lost due to all the damp in the bottoms ,, it got sunlite and raked up farely nice ,today,,and I thought I was gonna have to let it go ..