4020 Auction Oops

Deezle · Feb 23, 2015

Bought a 71 JD 4020 Powershift 2 weeks ago, not sure what I got myself into. After the tractor runs 10 mins all hydraulics(trans, steering, lift) stop working. Shut engine off, wait 15 mins, and they work again for about 10 mins. Changed filter, no change. Looking for possibilities/places to start with troubleshooting situation. Thanks

BANDITFARMER · Feb 23, 2015

Put a hydrolic gauge in an outlet on the back before you start it cold and see what pressure reading it gives when you stat it. Run it and keep checking the pressure till everything quits working. This will give you a good idea whats going on with it. Bandit

Deezle · Feb 23, 2015

(quoted from post at 12:06:09 02/23/15) Put a hydrolic gauge in an outlet on the back before you start it cold and see what pressure reading it gives when you stat it. Run it and keep checking the pressure till everything quits working. This will give you a good idea whats going on with it. Bandit

I'll have to pick up a gauge in town this week then. What would I be looking for with gauge attached to outlet? Typical #s? Thanks

BANDITFARMER · Feb 23, 2015

You want to see what the system pressure is in the hydrolics at start up and when everything quits. This is your starting point to figure out what's wrong with it. The pump may be bad or something else in the system could be bad. You just need to know the start up pressure and what it does the longer it runs pressure wise. It maybe a cheap fix like O-rings or a new pump. Bandit

Billpa · Feb 23, 2015

just wondering , is that system closed circuit and is that different trouble shooting than an open circuit ??

Tx Jim · Feb 23, 2015

Deezle
Does trans continue to operate properly? Did you clean trans oil sump screen?

Traditional Farmer · Feb 23, 2015

Well at least you know why it was at the sale.

Deezle · Feb 23, 2015

Thanks Bandit. No, transmission fails as well when rest of hydraulics go out. Wasn't aware of screen on transmission sump, definitely wouldn't hurt to clean that too. Does the entire system rely on transmission sump to maintain overall system pressure? Thanks

Tx Jim · Feb 23, 2015

(quoted from post at 15:40:55 02/23/15)
Does the entire system rely on transmission sump to maintain overall system pressure? Thanks

Yes. Access To screen is between rear hyd filter and rear axle housing.

2underage · Feb 23, 2015

Be sure you get a gauge rated for over 3500 psi.

tim s · Feb 23, 2015

Your sump screen is most likely clogged with brake lining...If some one used cheap oil it will deteriorate the lining and it ends up in the sump screen, the pump will suck it tight in a moment and all will stop, shut it off and the stuff relaxes a bit to let some oil paste then it all happens again...

gfs · Feb 23, 2015

go get two or three screens and change them regularly then change the fluid a couple of times and then get ready to put brakes on and it should be good to go for several years

Owen Aaland · Feb 23, 2015

The transmission pumps fills the oil cooler which serves as the reservoir for the main hydraulic pump. If you are not getting enough oil from the transmission to make up for the amount used by the steering, brakes, and other hydraulics they will stop working.

Bob · Feb 24, 2015

Powershifts don't have the oil cooler with the reservoir-sized tanks like the synchros do, and they have a live transmission pump, much like an automotive automatic transmission pump.

It is just a simple, thin/flat radiator which probably only holds a cup or two of oil.

QUITE a different setup than the synchros, where the pump stops when the clutch is depressed, and a reserve of oil is needed up front.

4020 Auction Oops

Deezle

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Deezle

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