2020 john deere

[alanmeg]

After an hour(maybe 2) or so of use, all hydraulic functions slow, start to chatter and barely function....and now the clutch just started slipping, but only when it acts up. Both filters and fluid have been replaced twice and the fluid appears clean and the level constant(before and during extended use).
The pressure at remote hookup remains constant at 1650psi, even while it acts rough. Even though the service manual specs 2250psi. Clutch and pto eventually grab, with just less than full throttle. I have been hesitant to adjust the stroke control valve until I feel there isn"t another problem(i.e. clog or faulty pump.)
All suggestions are welcome.

Here is the part that really confuses me......If I shut it down and let it sit for a while it is fine for another hour or so...depending on load conditions. Which makes me think clog, but where and how would it clear itself by sitting. I also worry about using a cheaper quality fluid...just because the first filter and fluid change is about when this all started.

 

[alanmeg]

FYI, Just re-checked the intake screen filter. Same as months ago, super clean along with the fluid and belly filter which were replaced a couple years ago.

 

[buickanddeere]

Sounds like a possible leak back to sump on the high pressure side. Any hydraulic equipment connected to the tractor?

 

[roger landers]

Hi , could it be a air leak on the suction isde causing cavatation . may be worse when warm .Clatter sounds like cavatation to me . check all suction side seals ,clamps etc.

 

[Tx Jim]

alanmeg
Picture with fitting on ported filter cover makes me think tractor has a loader installed. If so maybe hyd valve is convertible type which is open/closed center type and reverted back to open center with a blow sealing ring. Also could be rockshaft valves causing problem from leaking.

 

[alanmeg]

Yes,I have a loader on it

 

[buickanddeere]

Try isolating the loader supply & return to verify the loader control valve hasn't failed into "open center" mode.
Rockshaft piston/valve, power steering and scv valves can leak as well.
The suction side leak is certainly possible too.

 

[alan jacquin]

Thanks for all the tips.
Tonight I was focused on the clutch...didn't pull it apart(yet).
For the hydraulics, I will first check the belly paper filter bypass valve to make sure it wasn't stuck open while the fluid is still out, then refill, disconnect the JD48 loader control valves and go from there ....I might also try to boost the pressure with the stroke control valve since it has been constantly below the 1700-1800psi range. From what I understand, it should be higher than 1800psi, otherwise the pressure bypass diverts fluid to the steering and cuts off the other functions(the steering hasn't had any issues either). Standby pressure is supposed to be 2250psi per the manual.
I will make note of all the suggestions and address them one by one. Thanks again, I will post the results.

 

[alan jacquin]

Well, no luck so far, I checked the intake screen filter, the pressure control valve, and the stroke control valve along with its filter. All these components are really clean and don"t show any visual signs of wear. Although the stroke control valve was shiny where it contacts the seat.
Also, I attempted to remove one main pump outlet valve. Unfortunately with the loader in the way my socket plus universal joint couldn"t grab securely. I had to leave without sufficient time to spend breaking it loose.
Next, I added new fluid and ran through all the cycles for a half hour or so, it was all jumpy or barely functional at first with 2100psi standby. With slow improvements and occasional times when it worked perfectly smooth and normal, I thought I was getting somewhere. Then things started getting worse. I shut it down and re-checked the fluid, below the add mark...so I added more. Now suddenly there is really fluctuating standby pressure, anywhere from 300-2100psi. I tried to disconnect the loader and that didn"t seem to affect it at all. I am worried the valves in the pump are sticking, but not excited about taking the pump off to check all of them just yet, unless someone more wise suggests that I remove the main pump. Another thing that troubles me is that each time I replace the fluid it seems to get worse.
Any suggestions?

 

[Tx Jim]

Alan Jacquin
Before removing main pump or dis-assembly I'd install a flow-rater and determine how many gallons trans pump was pumping and under what psi. IMHO diagnosing problems is cheaper than swapping parts.