John Deere 300 Industrial hydraulic problems

[true temper]

The plug under the RH floor plate is the filter relief valve, not system relief. should have nothing to do with your problem. there is no system relief valve, you have a closed center system on your 300. My next guess is the stroke control valve in the pump. It tells the pump to "turn on or off". Pm me and give me your phone # and I will help you.

 

[true temper]

Paul is full of it, most of his list is for open center hydraulic systems, you have a closed center system.

 

[mpo111]

Hi,

I'd like to know if you ever figured out the problem with your machine. I have the same exact symptoms on my 300-B, and I''m about to start troubleshooting. First guess is the pressure valve or whatever it is called - the part that has the spring inside.



-Mike

 

[JD300]

I am now just getting back to this tractor problem.

1. I cleaned the suction screen, which was about 20% clogged with black rubbery stuff. Hyd. oil was clean, no water or silver color. Did not fix problem.

2. I checked the transmission bypass valve- was clean

3. I installed pressure gauges on the main pump (which is a serial # tagged 2.4 inch pump)--I believe the right side top port is pump output and the lower port is feed pressure from the transmission. The output pressure immediately jumps up to 2200 psi,even at idle rpm, that's good, but the charge pressure was maybe 5 psi, or less. At high rpm, the output would stay nicely at 2200 psi, and the charge pressure would slowly creep up to 20 psi. When a cylinder was activated, the charge pressure drops to 0. After the cylinder action is stopped, the charge pressure will creep up to 1-5 psi. After about 10 minutes of running, the charge pressure drops to zero and the output pressure becomes erratic, ranging from 2200 to 0.

Before heating up, the machine has plenty of power for digging or loader lifting. After warm-up, it becomes slow, weak and erratic. I noticed the Hydraulic oil reservoir tank is empty after running, and had a slight suction when I opened it (tractor off). No sign of hose kinks or dents anywhere.

4. I felt all the backhoe and loader valves for temperature; all stay cool except the steering column, which gets noticeably hot within a minute or two of running. For years, the steering has always been a little quirky--occasional interactions between loader operation and steering, occasional no power steering with a heavy loader load.

Questions:
1. How does the pressure control (priority) valve work? Does it shunt transmission charge pump pressure to the steering gear, or does it send main pump pressure preferentially to the steering?

Would a bad pressure control valve cause the main pump charge pressure to be so low?

2. What about the heating of the steering column? Would internal leakage cause the low charge pressure? Does the steering work on transmission pump pressure or main 2200 psi pressure?

3. Is there a way to test the transmission oil pump independent of the steering, or to plug off the steering for testing?

I got a new stroke control valve and plan to change it, but that does not seem like it will cure the problem. Any other suggestions/

Many thanks, Richard

 

[true temper]

You must have charge pressure for the main hydraulic pump to work. Sounds like you have a problem in your charge circuit. The problem with your steering is bad O rings in steering valve, causing high pressure leak. See other thread in hydraulic section on JD steering valve.

 

[JD300]

Thanks for your reply.

So the steering works off the high (2200 psi) pressure pump, not the transmission charge pump pressure?

If the steering was bypassing it, it wouldn't cause the charge pressure to drop?

If the priority pressure control valve was broken, would it drop the charge pressure?

Thanks again,
Richard

 

[JD300]

I wanted to post to let anyone know who may be reading this thread what the final resolution to the problem was, hopefully to help out anyone else with a similar problem in the future

1. the clutch pedal cross shaft to the reverser has a roll pin that connects it to the reverser valve. It had worked itself loose and was preventing the reverser clutch valve from closing thereby starving the main pump. Additionally, the shaft was slightly bent, which kept it from rotating properly. And, if those weren't enough, when the roll pin worked itself out, maybe a 1/4 inch, it was hitting a little peastone pebble that had wedged itself in just the wrong place up under there. All of these things kept the shaft from having enough torque to the reverser clutch control valve to close off the valve, which starved the front pump of oil.

2. My steering valve was shot, actually only the orings were shot, and all the oil was bypassing back to the tranny. You can test for this. There is a tee at the acumulator. It is easy to cap off the line to the steering valve to eliminate this as a possibility.

In my case, all the other things were ok:
** filters and suction screen
** pressure control (priority) valve
** oil filter bypass
** charge pump
** stroke control valve (I replaced mine)

Hope this helps, and thanks to the kind folks who helped me!
Richard

 

[LOOMER]

I have a 1970 1530 with these same issues. Can anyone tell me where this said clutch or reverser valve might be. thank you!

 

[jb1390]

I had a similar issue on my 300 that I just bought, and this thread came up when i was searching for a solution. I also have a repair manual, which proved extremely helpful when diagnosing my particular problem. I would like to post a background of how this system works and a basic way of testing it for those that do not have a manual.

The symptoms were identical on my machine to those described here, the only caveat is that my tractor has a 3 point hitch and no backhoe.

The 300 industrial has 2 hydraulic pumps. One pump is inside the transmission, the second is mounted in front of the engine, driven by a coupler. The pump ahead of the engine is a closed center, constant pressure pump. Oil to this pump is supplied by the pump in the transmission, which also runs the reverser (in my case the power steering), power brakes, and lastly, lubricates the transmission.

To test the transmission pump:
There is a right angle rubber hose running from a reservoir above the front pump, and into a cooler connected to the radiator. That hose is a bypass for all oil that isn't used by any of the other functions that are run by the transmission pump. If you take that off, oil should come out at a rate of 1 gallon every 10 seconds. When I took that hose off mine, it was completely dry.

Then, I had to determine where the oil was going. There are 3 test ports on the power reverser. One on the back of the housing (all take 1/2" sockets, and the plugs are 5/16" fine thread bolts I think), and 2 on the top of the housing when you take off the right footrest. Test the pressure at each of these ports. It should be 150 psi or so at the back port, and the same at the other two when shifted in forward or reverse (one plug is the forward clutch test port, the other is the reverse clutch test port). Mine checked out fine. This told me that the transmission pump is fine and was building pressure.

There is also a small possibility that a filter bypass is plugged inside the reverser housing. to check, pull the housing off the back of the reverser (6 socket cap screws) The valves inside and the springs were all clean on mine.

On the original posters issue-if he had done this test, his forward and reverse clutch pressure readings would have been very low. If they are low, the pressure regulator will not allow oil to leave the reverser until pressure is where it should be, which starves everything else of oil. This is my understanding at least. Mine checked out fine, so I will continue.

The last possibility is that one of the high pressure hydraulic systems was leaking internally, using all the oil. The transmission pump is only about 6 gallons per minute, and the main pump is 20+. If the oil is being used internally and not sent back to the main pump, the pump will run out of oil (which is why I was getting no flow out of the hose connecting the reservoir to the oil cooler). To test this, cap off each hydraulic function one at a time. (I used a hose with a high pressure gage on the other end. This allowed me to cap, and watch oil pressure all at the same time). In the end, it appears that my 3 point hitch is leakign internally, either in the cylinder or the valving. The hitch functions correctly, except when the oil pressure drops-there was no indication at all that there was a problem except for this test. With the 3 point hitch inlet capped, and only the bucket in the high pressure system at this point, it functions exactly as it's supposed to.

So in the end, it was the 3 point hitch.


I hope this description is helpful to someone experiencing this issue down the road. Like I said, it is the first thing that appears in google when searching this issue, so I figure I'd add my experiences to hopefully save someone else some headache.

 

[mmurphy]

:welcome: Thanks for your input of the problems found. The 400's are very similar.