thanks again guys
I will hunt around and also hopefully the weather will get warmer here in New Hampshire in the next few weeks to tinker on it
If it works fine for half an hour and then begins to shudder that tells me that the pump and hydraulics are fine, but there is some problem that happens when the hydraulic fluid heats up. I'm saying that because half an hour is about how long it takes for the hydraulic fluid in my JD 310 to heat up and when the fluid finally does heat up, there is a surprising increase in the volume of fluid. That's easy to see on the 310, because 310s have a fluid level gauge right hanging out on the side of the hood where you can't miss it. That level changes several inches from cold to warm. I don't know what that is in fluid volume, but I'd guess 10% or 2.5 gallons.
Kinda surprising that the volume changes that much even though I'm using the good old recommended hydraulic fluid that most John Deere commercial owners use - John Deere 303 fluid.
I'm guess that you know the JD 300s are like lots of JDs in that they use a closed center hydraulic system - so it is very different from the hydraulics on most other Ag or Compact tractors.
Based on what you've said so far, I think your pump is fine. Keep in mind that closed hydraulic systems are sensitive to being overfilled.
So.....also based on the half hour before stuttering starts happening and your saying that oil or hydraulic fluid is overflowing the fill port, My first guess would be that you have too much of the wrong fluid in the hydraulics. Drain out a gallon or two and see if that helps. It won't hurt anything to run it that way for awhile.
BTW, if you are running motor oil instead of hydraulic oil in there, better check the ops manual. My newer 310 definitely requires hydraulic oil in the hydraulics, but it isn't impossible that some of the older 300 series could use motor oil. I know for a fact that some owners did so, and I also know that they had to pay special atttention to how much oil was in the system because motor oil expands differently than hydraulic oil. But I don't know which or what. Anyone know?
If draining out some fluid doesn't help, - and you have real hydraulic fluid in there - then you have heat-related sticking going on in either one of the relief valves or the accumulator. These are all easy fixes which don't require detailed mechanical knowledge and are not expensive. Stay out of that pump for now.
Nice tractor, enjoy
rScotty
