JD4020 Hydraulic issues

[sycamoreview]

Its a Syncro, and I have the same behavior with and without the clutch pedal depressed.

 

[sycamoreview]

Problem is, sometimes its fine, then 10 seconds later, eh its slow, then its back 15 seconds later. Very odd... I will say, when moving it actually operates better, sitting no. I've also tested increasing RPMs when parked, it helps, but depends....

Also I did notice, sometimes the transmission wont shift from park, but after sitting for a little then you can get it to go.

 

[Tx Jim]

Problem is, sometimes its fine, then 10 seconds later, eh its slow, then its back 15 seconds later. Very odd... I will say, when moving it actually operates better, sitting no. I've also tested increasing RPMs when parked, it helps, but depends....

Also I did notice, sometimes the transmission wont shift from park, but after sitting for a little then you can get it to go.

Sounds typical for a high pressure internal leak. With hyd oil at operating temp remove round plug in rear of trans case, 3 pt raised, engine operating at idle speed look in open hole for moving oil. If moving is visible there's a leak in rockshaft hyd circuit. Next using a laser thermometer check temperature of each hyd control valve. HYD control valve with highest temp is likely the hyd problem. Does this tractor have frt end loader installed? Trans not shifting sounds more mechanical problem than hyd problem. Is hyd oil level at full mark on the dipstick?

 

[sycamoreview]

No loader on it, all new fluids and filter, and clean screen. The non shifting wont go from part to anything, like you cant pull on it, happens when all the hydraulics are being used, like lift arms up and a implement in the air (trailer plow).

I am going to get a gauge kit and ill borrow a laser thermometer to check temps.

 

[Tx Jim]

Syncro-range transmission doesn't have any correlation with how hyd operates or how SR trans shifts. If tractor is parked on a slight incline then trans can be more difficult to get out of park. I suggest to check for wear in bushings in shifter drums located in dash & slack between drums Slack can be eliminated with shim washers

 

[sycamoreview]

Will be sure to check that too,

 

[620 John]

If a laser thermometer gets you in the right direction for a suspect valve, you could maybe cap off the supply line going to whichever valve is suspect. Then if everything else works fine with the valve capped, that would for sure tell you if there's an issue with that valve. I believe most of those fittings on that tractor are JIC which you can find caps for on eBay or wherever.