Deere 4020 No Hydraulics

[310SK]

A customer of mine bought a Deere 68' 4020 Diesel PS at auction sight unseen and had it delivered to my shop to go through. Upon arrival it had no hydraulics, no steering/brakes, and wouldn't move.
It had no had oil in it due to a load shaft leak, so we fixed that, cleaned the strainer and put in new filters and oil.
Still no hydraulics, verified that front pump shaft is spinning, pump makes 0 noise though.
I removed the filter housings to see if any oil was flowing while the engine was spinning and there was no oil in either filter housing, making me believe that the rear pump has a major issue.
I want to verify that I am not overlooking anything else before we split it for a rear pump, I have limited experience with the Powershift.

 

[Dieseltech]

Some early Power Shift models have a flywheel cold start disconnect clutch. If it has one make sure the control lever is forward so the transmission charging pump will
run. Pump is at the trans front, not at the rear like Synchro trans models.

 

[Tx Jim]

Ditto what Dieseltech stated about possible disengaged damper clutch or possibly failed/slipping damper clutch.

 

[used red MN]

The lever for the trans disconnect is on the left side of
the dash support by the clutch pedal. There is a knob
to release the lever to re-engage it. If that brings the
hydraulics back but the tractor still does not move
there is also a ..tow disconnect.. down on the side of
the trans above the filters and back a bit. If still no
hydraulics I would suggest to try to destroke the hyd.
pump.

 

[wore out]

The lever on your 4020 will be similar.

''Ahead'' is normal/engaged, when you pull it rearwards it disconnects a clutch at the engine flywheel.

When pulled back, it latches, to release, pull rearward, then pull little black knob at the left side of the steering pedestal, then slowly allow the lever to move forward and engage the disconnect clutch.

The release mechanism can get rusted/sticky making it hard to pull, and it's VERY hard to pull unless you pull back on the disconnect lever at the same time, taking the pressure off of the latch mechanism.

Disconnect lever, D, and latch knob, Y.

I hope you find this is why there's no hydraulics!