JD 4300 stops moving in forward and reverse after a few minutes - engine still runs

[GreenRust]

I have a John Deere 4300 HST compact tractor with a 420 front end loader. I am the second owner but have had the machine for over 10 years. I think it was built in 2000 and only has just over 300 hours on it. It has functioned normally for years. I have a problem I cannot figure out. I work full time so I mostly use the tractor on the weekends. When I first start the tractor I can drive for a few minutes then it stops moving in forward or reverse. The engine is running fine the whole time and does not surge or stall or change in any way. FEL and PTO still work. After it sits for a few minutes I can get it to move a few feet then it stops moving again. Shifting the range lever in and out of neutral sometimes helps me get an extra foot or two. When this first started happening I changed the hydraulic fluid, filter and screen hoping that would help. To my surprise there was no suction screen in the sump. The fluid was dirty and overfilled by at least a gallon. There was no noticeable change to the problem after replacing the fluid and filter and installing a new suction screen. I知 stumped and appreciate any ideas.
Thanks

 

[beenthere]

Sorry to hear about this problem. Others may know or have an idea what is happening.

If me, I would explore getting a sample of the hyd. oil tested for any deposits that may lead to a solution.

You know the history for the last 10 years. How many hours did it have before you bought it 10 years ago?

The fluid was dirty and overfilled by at least a gallon.

When did you do this, within your 10 years?


A check with your Deere dealer to learn if there are any records on file for this s/n that may offer an explanation.. in a flood? changed the instrument panel and lost the hour log previous to your purchase?

but :welcome: to TBN

Hope a solution can be figured out for you.

 

[GreenRust]

Thanks for the reply and welcome. The previous owner is family and I know he didn't do any damage to the tractor. The over fill on the hydraulic fluid was most likely me in a hurry. I don't know why the old fluid was dirty. It wasn't sludge but it was darker than I think it should have been.

 

[Tx Jim]

Welcome to TBN
I'm not familiar with that model but I'll guess there's a port where one can check pressure of hydro trans. Does FEL operate correctly?

 

[GreenRust]

Thanks for the reply and welcome. There are forward and reverse test ports. I do not have test gauges but I think I'll need to add them to my shopping list. Everything else works when I lose forward and reverse, PTO, FEL, and steering all still work. When it stops moving the pedals go all the way to the floor with absolutely nothing happening. Most of this is new to me as I am trying to learn as I go but I'm hoping that means it is something in the linkage or a sensor or something dumb I am missing. I also fully realize the tractor doesn't care what I hope it is :mur:.

 

[beenthere]

A page from the troubleshooting section of the service tech manual.. hope it is linkage.. if been in the brush, might have happened..

 

[GreenRust]

Thanks for posting that. I do use it in moderate brush, tall grass with saplings and whatnot. Nothing looks out of whack just looking but hopefully this weekend I can get someone else to stomp on the pedals (with the engine off!) and at least make sure everything that is supposed to push, pushes and everything that is supposed to pull, pulls.

 

[GreenRust]

I got my hands on the tech manual. Nothing jumps out at me as the possible culprit. As previously mentioned, my next step is to follow the control linkage to look for anything stupid. Then checking the few switches that aren't already bypassed. Assuming that doesn't solve anything it looks like my next step is to check the hydrostatic pump pressure and charge pump pressure. I have never done any real hydraulic trouble shooting before so I have a few questions. First, since the tractor does move for a few minutes after I first start it don't the pressures at that point almost have to be within spec range then drop when whatever causes it to stop moving happens? I just want to make sure testing the pressure will actually tell me anything. Also, as much as I dislike cheap one time use tools, being that is the only hydraulic equipment I own, is there a good reason not to by a cheap ~$75 test set on Amazon versus better grade or JD factory setup for several times the cost? I'm trying to figure this out as I go so please excuse what may be very basic questions. If I can't figure this out in the next couple of weeks I am going to have to bite the bullet and take it to a shop.
thanks again

 

[Zebrafive]

I would start with the linkages.
Looking at JD parts, I do not see much that can break for reverse (other than a bolt/pin falling out)
Forward does have a keyway in the lever from the pedal to the shaft it moves.

Parts also shows a coil near the pedals. I do not know what this is for. Your tech manual should say.


For testing the hydraulic pressure. You need a gauge, a hose and an adapter to connect the hose to test port, and the hose to the gauge.
You did not post pressures for the test ports. You want a gauge that reads around double, so reading will be in the middle of the gauge's range.
The hose can be small ID, it only needs to send pressure, not volume to the gauge.

Test ports plugs may be same or different size. I assume they will have metric threads. You need to check. Also if they are sealed with an O-ring have extras on hand.
Take a test port plug(s) and your hose to hydraulics shop and have them sell you the adapter(s) so you can connect the hose to the test ports. Also get an adapter (if required) to connect the gauge to the other end of the hose.


What does the tech manual say to do in the event of too low of pressures at the forward/reverse test ports? If repairs are beyond your comfort zone, you may want to take it to a JD dealer if the linkages check out OK.

 

[beenthere]

The test gauge recommended in the service tech manual goes to 10,000 psi. Pretty good outline of parts needed.. to connect.