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JD 6200 Selective Control Valves

Dick W. Pirkey, Jr. I recently inherited my fathers JD6200 and have ran in to a snag, since I am not at all familar with modern tractors, old collector tractors are my passion.
The return lines leading from the control valves, to the filler port and the return line to the collector bottle keep blowing off and spewing fluid everywhere. When I go to pull back on the control lever in the cab, they blow off!!!
What's up!!

Dale G. Basgall Dick ; is the filler port you are talking about directly above the main hydraulic pump on the 6200? I may be able to help out but I need to know a few more things. Send back on the forum if you want more assistance.
dwpirkeyjr The filler port is down on the left side and appears to go to the lower portion of the axle housing. It is a 300 series control system. The top 2 ports attach to the plastic bottle and the bottom 2 ports flow to the filler port.
Dale G. Basgall Dick ; Dick ; There are three different hydraulic pumps listed for that 25cm3 , 25/40cm3 , 25/41cm3 and all three seem to be simular axial piston hydrostatic pumps and going to the SCV(s) (selective control valve(s). The drain from the bottle appears to go directly into the top of the transmission case and in one configuration a return hose is used with a conventional looking hose clamp.

In the filler port is it lower than the plastic bottle? The way lines blow off is obviously from more oil flow into the return system than it can possibly drain into the hydraulic reservoir.

Is it one specific SCV that does it. The scv(s) are closed center valves so you should have little to no return flow from those valves when nothing from the scv is being used.

Do you have quick disconnects from the scv. Is it possible that someone could have filled the hydraulic oil with an impliment attached and that when the trans oil get's warm it could have to much fluid in the system? Anyway depending which hydraulic pump you have will determine what return system and lines were used on your 6200. All are simular in operation but the exact porting to return is different, send back on forum which pump you have I will go back to the system schematic.


dwpirkeyjr The pastic bottle has no drain, it is to be pored out when full according to the manual(OMAL77469 Issue G5)and the other return line goes to the filler port. They never had any clamps they were just hand pushed onto a nipple. I put a new hose on the one that went to the bottle. The tractor was nearly out of fluid(not touching the stick)and it blew off the hose, I put in 3 gallons and it came up to full and it still does it.

Hydraulic System
Type---Closed center with Load-Sensing control
Pump---Axial piston pump
System pressure---Min. 3000 kPa(30bar;435 psi)
Max. 20000 kPa(200bar;2900 psi)
Steering system---Hydrostatic power

Dale G. Basgall dwpirkeyjr ; that bottle must be for some type of case drain, I looked in the parts pic and with your 300 series hydraulic valves it is apparent that electric solenoid controlled valves have many piping configurations dependent upon the hydraulic pump cm#.

I am going to look into the repair manual in the morning I don't have access to that today. Something in that valve may not be functioning correctly. Even with hydraulic pump flow at it's maximum in the return circuit from the SCV valves and into the case filler seems that a transmission vent may be plugged or something simple like that.

I will check in the AM in the repair manual and get back on the forum to let you know what I can find out.

The load sensing system is closed center which is simply when the hydraulic valves are in neutral the spools block the flow of hydraulic oil from flowing through the control valves.

The main hydraulic pump is in low pressure standby, and after a control valve function is activated the hydraulic pump is stroked to maximum until backpressured hydraulic oil is routed through a flow pressure compensating valve on the main hydraulic pump.

It saves fuel over the conventional John Deere pressure compensated systems and is very simular to the Cat load sensing systems.

Just from an on spot feeling it seems a vent tube may be plugged or something rare like that.

dwpirkeyjr Picture
dwpirkeyjr I erred, it is a 200 Series, based on the pictures on the selective control valve dial. There is no(B,lock) picture so I think it is a 200 Series. That bottle has a line that comes from the top of the top 2 hydraulic ports, between the 2 ports is a crossover line hooking them together and the bottom two ports have a line that goes to the trans/hydraulic filler port.
I might mention that this JD6200 has 2,177 hours
on it has has been poorly maitained.

Dale G. Basgall dwpirkeyjr ; those lines on that tractor you described as return lines to the top of the filler area are actually overflow lines for the SCV connectors (pioneer quick disconnects) to attach and detach the impliment easily.

The top plastic container is a crossover catchment. Neither lines should have return flow in them. What is happening is that there may be dirt or a bad O-ring in the quick disconnects or a piece of debris in the scv valves themselves.

A solution would be to order the O-Rings for the scv valve giving you the system return into the overflow oil hoses.

Do you have a John Deere dealer close by to you? Do you have a parts pic so you can find the O-Rings needed? If not write back on the forum. Those valves look complicated from pics but they are really not hard to work on.

Write back if you want to try to do the work yourself and need help.

dwpirkeyjr That is correct. I called them return lines because the fluid returns down them from the SCV's, one down to a plastic bottle and one down to the filler port. I see where there was some confusion, as to that is also where, if there were any lines hooked up one would be an egress and one a digress, but I have none of those lines hooked up in the ports.
Thanks for the info. I do not have the drawings but I have replaced external O-rings before but the ones you mean are probably the internal, not the exposed external o-rings, I suspect. i am trying to decide to buy the parts/tech. manuals to go with the operator manuals. I saw some microfiche diagrams on ebay. I would like to look at the drawings to see if it is something I could do as the JD dealer is 40 miles away and a hairy haul ay that!
Pirkey

Jd6200 I am having the same problem on my 6200. No matter what the pressure is set on or what you do it blows the lines out of quick couplers as soon as you pull the lever. Did you ever diagnose the problem or did you have to take it to the dealership. I am willing to do the work myself but do not have the tech manual.


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