4440 Hydraulics

stew70 · Apr 8, 2019

Installed new hydraulic pump on a 4440 with Quad, everything worked fine for probably 30 minutes then hydraulics quit. Came back to tractor a few days later and hydraulics worked for maybe 15 minutes and quit again. I was told by one guy that the transmission supply pump was bad. Since I had just put a $1250 hyd pump on, wanted to see if there is a way to verify that is the problem. The clutch and trans seems to be working fine, 3 point will not raise, scv's do not work, steering doesn't work and loader with joy stick doesn't work. Any help would be appreciated.
4440

Kory1998 · Apr 8, 2019

What started the problem or what was the reason as to why you changed out the front hydraulic pump.
I had one that I worked on had similar issue come to find out it was that the guy put some off breed hydraulic fluid in it and it started to wipe the paint off the inside of the case and it got down into suction screen inlet tubes and Was not supplying enough hydraulic fluid, customer complained that he lost all hydraulic functions and he told me front pump was bad and he swore up and down and he bought a pump but come to find out it was just as simply as that. Could also be air in system but I think by then you would have all air bled out of tractor since you used it twice. My guess would be like with what your saying you have a leak or are losing sump prime to front pump.
Not saying that I am 100 percent correct, and I’m also sure some one will come on hear and blast me for saying this but it’s just like the old saying goes opinions are like butt holes everyone got one and their either dirty or clean!

stew70 · Apr 8, 2019

the pump was leaking bad and I had fuel issue so I had the tank off and the cooler off to wash out. I decided no better time to change the pump. I have changed the filter or cleaned the screen yet, because I had just changed the filter and cleaned the screen less than 15 hours ago. But I'm going to do it again tomorrow just to be sure. I did use mystic oil instead of John Deere.

Bob · Apr 8, 2019

Drain rear end and check suction screen for debris. Clean, as needed.

Then, no need to guess.

You need a factory manual for the exact details on how to check the transmission pump pressure and flow in the clutch valve area.

Oil in excess of the requirements of the clutch, PTO clutch, PTO brake, and quad range planetary is piped forward to the main hydraulic pump, along with "function return" oil.

The front pump cannot draw it's own oil, it needs to be fed oil that's been PUMPED up front the main pump by the transmission pump.

Oil in excess of main pump needs fills the reservoir ahead of the radiator, and above the main pump, flows through the cooler, and back to the transmission lube circuit and sump.

Tx Jim · Apr 9, 2019

stew70
Welcome to YT
I'll add to what others stated to check hyd stand-by pressure if you haven't already done so. Pressure should be 2250 psi but can be set as high as 2350 psi. If tractor has quad-range trans hex shaft that powers trans pump could be rounded off allowing trans pump to stop pumping when engine is running.

stew70 · Apr 9, 2019

Thanks Bob I will clean today.

stew70 · Apr 9, 2019

where is the best place to check the pressure and how do I check the hex shaft?

Tx Jim · Apr 9, 2019

If your 4440 has QR trans unbolt 3 pt center link bracket,remove hex plug that was located under bracket then pull shaft out to inspect for wear. Stand-by pressure can be checked at rear breakaway coupler when remote cylinder hoses attach.

buickanddeere · Apr 9, 2019

Need a service manual . The pages of images, diagrams , descriptions and instructions can not be replaced by a few sentences on a chat site .
The free parts book on the JD web site will be of some benefit .

Bob · Apr 9, 2019

For now, check hydraulic pressure at one of the implement quick couplers.

You can check transmission pump pressure at the port on the clutch valve below your left heel marked "CL".

IIRC, should be around 165 PSI.

That indicates the transmission pump is operating, and the hex shaft pump drive hasn't sheared.

As a "FYI", the "hex shaft" we are talking about extends from the rear of the tractor ("3" in the illustration) all the way forward into a hex drive adapter in the engine crankshaft, passing through (and driving) the transmission pump on it's way.

Eagle Beagle · Apr 9, 2019

And if you can't easily pull that shaft out, it's a dead giveaway that the pump, shaft or both are shot.

Beagle

Eagle Beagle · Apr 9, 2019

In my experience the small amount of metal removed from a rounded shaft will hardly be noticeable in the screen,filters or whatever.

If you can't pull the shaft out, that tells you the hex shaft is worn. Tractor split is the next move.

Beagle

Bob · Apr 9, 2019

(quoted from post at 08:42:53 04/09/19) In my experience the small amount of metal removed from a rounded shaft will hardly be noticeable in the screen,filters or whatever.

If you can't pull the shaft out, that tells you the hex shaft is worn. Tractor split is the next move.

Beagle

The O.P. stated "The clutch and trans seems to be working fine"
which, if true would rule out a sheared transmission pump drive.

4440 Hydraulics

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