Ehydro issue

Lt340 · Sep 10, 2021

My JD 4320 is having an issue with the ehydro. I was bush hogging this week and the tractor did great. When I was done and turned off the PTO and started to load the tractor on the trailer it wouldn't pull up on my ramps. I had to throttle wide open and it barely pulled up on the trailer. When I got home I unloaded the tractor and drained the hydraulic fluid so I could check the screen in the sump. The screen was clean. The fluid and filter was changed about 6 months ago but I went ahead and changed the filter again. After I got the fluid back in and new filter I cranked the tractor and got all the air out. The hydrostatic transmission didn't work at all. No forward or reverse. I checked all electrical connections. Those were good. After about an hour I cranked the tractor again and everything worked fine. I figured it was a fluke until I bush hogged again yesterday. Same issue. The tractor did fine while I was bush hogging but once I turned off the PTO the tractor didn't have any power to pull up on the trailer. Also when I throttled down to turn off the PTO the tach on the tractor stuck at 1100 rpms. Got the tractor loaded and home. I left the tractor loaded until last night. When I cranked it to unload it everything was working fine. I'm stumped? Anyone know what's going on?

plastikosmd · Sep 10, 2021

No clue but following to see what issue is

beenthere · Sep 10, 2021

lt340
Welcome to TBN
Hope someone will have a good clue for you. Sounds like you are zeroing in on the conditions that cause the problem.
Let us know if you nail it down, or pass on continued clues of what is happening.

texasranger556 · Sep 16, 2021

I'd lean toward electrical. Can you tell if the engine loads down at all when it won't move and you're pushing the pedal all the way down?

I'd try easy stuff first like check/re-mate any connectors down low associated with the hydro...maybe got a stick jammed in the wiring while brush hogging.

Is your PTO engagement a manual lever or an electric switch?

Lt340 · Sep 19, 2021

The pto is electric pull switch. There is nothing jammed up underneath. All the connections of the wiring to the pedals are connected and good. Once the tractor sets for a while it's all good. I'm thinking either electrical or a fluid transfer from the PTO valve.

TractorGuy · Sep 20, 2021

Load match switch turned off? I don't use mine often but if I forget to turn it off the tractor is very sluggish when I start it back up with the switch on.

Lt340 · Sep 20, 2021

The switch is on but the load match switch wouldn't cause this issue. It's like the hydrostatic transmission stops working completely. Works fine while mowing but as soon as you turn off the PTO there is absolutely no power to the pedals

Lt340 · Sep 20, 2021

Besides.... it does it no matter of load match is on our not...

Deere Dude · Sep 20, 2021

Recheck oil level. If mine is 1/2" low that is over a gallon low/ But is a 3720/

super55 · Sep 20, 2021

Does the tractor make the high whine sound like when you are in C range and it goes into relief when it won't go up the ramps?

It's interesting with your symptoms it's giving. Did you try going up the ramp with PTO engaged (With the shaft disconnected obviously) and did it make a difference. If it does then I would lean towards you have a weak relief valve in the hydraulic drive circuit. It's not as noticeable when cold because the fluid has more viscosity but when warm it is apparent. This is just a guess but when the PTO is engaged the fluid flow changes and the circuit is bypassed.

Might be time to invest in a tech manual. These relief valves are kind of pricey and there are multiple ones so it would be worth the investment.

TractorGuy · Sep 20, 2021

Lt340 said:
The switch is on but the load match switch wouldn't cause this issue. It's like the hydrostatic transmission stops working completely. Works fine while mowing but as soon as you turn off the PTO there is absolutely no power to the pedals

All I can say is if I turn my 4310 eHydro off and restart it with load match turned on it won't hardly move until I turn load match off.

Lt340 · Sep 21, 2021

super55 said:
Does the tractor make the high whine sound like when you are in C range and it goes into relief when it won't go up the ramps?

It's interesting with your symptoms it's giving. Did you try going up the ramp with PTO engaged (With the shaft disconnected obviously) and did it make a difference. If it does then I would lean towards you have a weak relief valve in the hydraulic drive circuit. It's not as noticeable when cold because the fluid has more viscosity but when warm it is apparent. This is just a guess but when the PTO is engaged the fluid flow changes and the circuit is bypassed.

Might be time to invest in a tech manual. These relief valves are kind of pricey and there are multiple ones so it would be worth the investment.

I have the manual on my computer and a hard copy. I was leaning toward a relief valve too. I had to have the PTO valve cleaned and rebuilt because the previous owner obviously never used the PTO and the valve gummed up. It is highly possible it could be the relief valve because ever since my mechanic rebuilt the valve sometimes you have to turn the PTO switch on a off a couple of times to get the PTO to stop.

beenthere · Sep 21, 2021

obviously never used the PTO and the valve gummed up.

That happening would be a surprise to me.. but maybe possible.
Hope you fine the problem, but sounds like you are on the right track.

Lt340 · Sep 27, 2021

OK.... after weeks of checking this and doing that I have determined that my issue is lack of power due to the hydraulic oil getting hot. I have basically done everything I know to do to help the situation. I have made sure the oil cooler was clean and that it was pumping oil correctly without any internal clogs, I have thoroughly cleaned the radiator inside and out, I have installed a 16" electric fan onto the oil cooler to give it more air flowing to it, I have cleaned all hydraulic oil screens, installed yet another new filter and the hydraulic oil is new. I get no warning lights telling me the hydraulic oil is getting hot nor does my engine temperature gauge get too hot while I'm using the tractor. I bush hogged today for about 4 hours and the engine never got hot but I was loosing torque on the hydrostatic transmission. It was very sluggish trying to pull a hill even in low gear. I just don't know what I need to check next??

super55 · Sep 27, 2021

Sorry to hear about the hydro woes your having. If its running good when cold then viscosity might be an issue. If you are using hy-gard lo-vis (J20-D) you might want to go with just regular hy-gard (J20-C) but I have a feeling it wouldn't change much.

Some things to check might be when it doesn't want to move is to make sure the large suction line isn't collapsing on the left side of the tractor. I have seen posts where unlikely but it has happened that the hard rubber hose collapses on itself and then restricts flow.

Relief valve seems unlikely because it would do it cold as well. If it still runs great when PTO is engaged when warm like discussed in previous posts it might be something to look into.

The other thing that I have seen a related problem to this is a worn torsional damper (like a clutch for hydros) or you have a worn charge pump (on the side of the engine) or a worn hydro pump.

Best advice is get a pressure gauge and start pressure testing the system when it is symptomatic. Warm expanded parts and lower viscosity fluid is giving you pressure relief somewhere in the system now you just have to isolate which one it is because these parts can get real pricey really quick. Might be worth sending it to a reputable dealership to diagnose.

texasranger556 · Sep 27, 2021

When it's acting up, if you run the engine at idle and hold down the forward pedal while in gear, do you hear any noises coming from the transmission?

When I first bought my 4400, the transmission would "chatter" due to low charge pressure. I could hear what turned out to be trans pump cavitation (and could feel it in the pedal which I doubt you could "feel" through an ehydro pedal).

Lt340 · Sep 28, 2021

texasranger556 said:
When it's acting up, if you run the engine at idle and hold down the forward pedal while in gear, do you hear any noises coming from the transmission?

When I first bought my 4400, the transmission would "chatter" due to low charge pressure. I could hear what turned out to be trans pump cavitation (and could feel it in the pedal which I doubt you could "feel" through an ehydro pedal).

No there is no noise. Just hesitation to move. I have found a sharp bend in the return hydraulic oil line from the cooler that obviously the previous owner bent. When at idle you can put your hand on the line and feel a slight resistance in the fluid pressure. I spoke with my mechanic friend that worked for John deere for over 30 years. He told me that if the bend was sharp enough it could definitely build heat. I have order a new line and also I ordered a double tube oil cooler for the tractor to replace the single tube cooler. I used the tractor tilling today for about 2 hours and didn't have much issue. It's just an aggravating issue.

Lt340 · Sep 28, 2021

super55 said:
Sorry to hear about the hydro woes your having. If its running good when cold then viscosity might be an issue. If you are using hy-gard lo-vis (J20-D) you might want to go with just regular hy-gard (J20-C) but I have a feeling it wouldn't change much.

Some things to check might be when it doesn't want to move is to make sure the large suction line isn't collapsing on the left side of the tractor. I have seen posts where unlikely but it has happened that the hard rubber hose collapses on itself and then restricts flow.

Relief valve seems unlikely because it would do it cold as well. If it still runs great when PTO is engaged when warm like discussed in previous posts it might be something to look into.

The other thing that I have seen a related problem to this is a worn torsional damper (like a clutch for hydros) or you have a worn charge pump (on the side of the engine) or a worn hydro pump.

Best advice is get a pressure gauge and start pressure testing the system when it is symptomatic. Warm expanded parts and lower viscosity fluid is giving you pressure relief somewhere in the system now you just have to isolate which one it is because these parts can get real pricey really quick. Might be worth sending it to a reputable dealership to diagnose.

Thanks buddy. I haven't noticed the suction hose collapsing. I don't think it's a relief valve either because it would do it all the time. I was wondering about the pump too. Unfortunately I have found out the hard way that this tractor wasn't taking care of properly. When I purchased it the hydraulic system was severely dirty and had water in the oil. I had to change fluid and filters three times to get it cleaned. The system was so dirty that the PTO valve had to be rebuilt due to being gummed up. There is definitely something that isn't right but I'm working on it...