4020 John Deere Hydraulic Problems.

[Kengram]

I have a 1968 4020 John Deere I need help with! Last year I had this tractor in a shed and someone parked so I couldn’t get it out very quickly, so with Riding the Clutch and back and forth finally made it out, the hydraulic whining I lost steering and loader functions and it never recovered. I took the rockshaft off and replaced the pump inside with a New JD $1,180.00 pump and it still did not fix the problem, I loosened the filter housing while it was running and not much came out. I’m at a lose can someone help?

 

[wore out]

I have a 1968 4020 John Deere I need help with! Last year I had this tractor in a shed and someone parked so I couldn’t get it out very quickly, so with Riding the Clutch and back and forth finally made it out, the hydraulic whining I lost steering and loader functions and it never recovered. I took the rockshaft off and replaced the pump inside with a New JD $1,180.00 pump and it still did not fix the problem, I loosened the filter housing while it was running and not much came out. I’m at a lose can someone help?

You must have cleaned the transmission pump suction screen, right?

 

[JD Dave]

More likely a dirt problem rather than a mechanical problem. Suggest you clean the suction screen, replace the filter and change the hydraulic oil. Idle the tractor for a few minutes and check the hydraulic operations. If the problem persists, then check oil flow and pressures. The original tech manual is the bible for mechanics.

 

[Tx Jim]

Changing parts such as pumps without performing proper hyd diagnostics is very similar to playing Russian Roulette!! Has hyd filer been changed lately & hyd oil suction screen been checked/cleaned. Another possibility is hyd filter relief valve is stuck open. What type hyd valve controls loader(scv or ind)?

 

[ss55]

I have a 1968 4020 John Deere I need help with! Last year I had this tractor in a shed and someone parked so I couldn’t get it out very quickly, so with Riding the Clutch and back and forth finally made it out, the hydraulic whining I lost steering and loader functions and it never recovered. I took the rockshaft off and replaced the pump inside with a New JD $1,180.00 pump and it still did not fix the problem, I loosened the filter housing while it was running and not much came out. I’m at a lose can someone help?

Part of your experience is normal on a Syncro-Range transmission. You probably know this: On Syncro-Range transmissions the charge pump in the transmission shuts off when the clutch is depressed. Once the small hydraulic reservoir above the oil cooler is empty all hydraulics are lost until the clutch is reengaged. The never recovering is the strange part, maybe the charge pump lost prime?

 

[Kengram]

You must have cleaned the transmission pump suction screen, right?

I cleaned the screen, and replaced the hydraulic filter, it’s like it’s lost its prime or somethin!

 

[JeffinAB]

Pump drive coupler splines gave out maybe?

 

[Scott 730]

Maybe something as simple as a piece of crud in the stroke valve. Proper diagnostics before throwing parts at a problem can save alot of money, time, and un needed parts.

 

[Kengram]

Pump drive coupler splines gave out maybe?

They are new also.

 

[Kengram]

Maybe something as simple as a piece of crud in the stroke valve. Proper diagnostics before throwing parts at a problem can save alot of money, time, and un needed parts.

How do I find that out, here in podunk Arkansas it’s hard to find a good mechanic for this 4020

 

[used red MN]

They are new also.

Hello Ken welcome to YT! Just incase you don’t understand they are talking about the splines on the main pump up front. May have coincidentally failed at the same time. It may also be a good idea to manually de-stroke the pump, this sometimes clears out debris and returns normal operation. I see the red post banner so someone else may have said this. Beyond this obtaining a JD repair manual and following the troubleshooting in there is the best approach. I think it is fairly rare for the charge pump you replaced to fail.
Edit to add: Do a search on manual de-stroke for more info on that.

 

[Kengram]

Hello Ken welcome to YT! Just incase you don’t understand they are talking about the splines on the main pump up front. May have coincidentally failed at the same time. It may also be a good idea to manually de-stroke the pump, this sometimes clears out debris and returns normal operation. I see the red post banner so someone else may have said this. Beyond this obtaining a JD repair manual and following the troubleshooting in there is the best approach. I think it is fairly rare for the charge pump you replaced to fail.
Edit to add: Do a search on manual de-stroke for more info on that.

Thank you for the welcome, I will check the front pump coupler again. I thought after I replaced the pump in the rear and started the tractor, I loosen the filter housing and thought it should have drowned me in fluid, but very little came out. Sorry about all the questions but a 4020 is not what I’m use to, a two lunger is what I’ve always used. Thanks again

 

[used red MN]

Hello Ken welcome to YT! Just incase you don’t understand they are talking about the splines on the main pump up front. May have coincidentally failed at the same time. It may also be a good idea to manually de-stroke the pump, this sometimes clears out debris and returns normal operation. I see the red post banner so someone else may have said this. Beyond this obtaining a JD repair manual and following the troubleshooting in there is the best approach. I think it is fairly rare for the charge pump you replaced to fail.
Edit to add: Do a search on manual de-stroke for more info on that.

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[Fixingfarmer]

Yes main hydraulic pump from Deere is going to be more like 5,000. Check that little coupler up there attached to the crank shaft pulley it got me once. Not much will come out that filter housing. It sounds like you did the transmission pump?

 

[used red MN]

Yes main hydraulic pump from Deere is going to be more like 5,000. Check that little coupler up there attached to the crank shaft pulley it got me once. Not much will come out that filter housing. It sounds like you did the transmission pump?

And make sure you look at the actual shaft going into the pump, that has to be turning.

 

[Tx Jim]

Did you check hyd filter relief vale to be sure it's not stuck open?