John Deere 300 Industrial hydraulic problems

[JD300]

I have a 70's John Deere 300 Industrial tractor/loader (similar to a 1020) with a JD9250 backhoe attachment which has served me well for 15 years of occasional use. Recently, it has developed a hydraulic problem. First, after using it for hours, suddenly the loader and backhoe would not operate at all. Engine runs fine, transmission fine, tractor moves fine. No funny noises, just nothing. After about 10 minutes, hydraulic function came back, then came and went intermittently.

The next day, tractor ran fine for about 30 minutes, then the same intermittent loss of hydraulics. Next day, same thing. Oil level is fine.

I thought it might be clogged filters, so I changed both hydraulic filters (the transmission one and the loader return one. I also changed the hyd. fluid. The oil fluid and filters were clean as new. So I started it up, let it idle to self-purge for about 20 minutes, and it operated fine for about 5 minutes then, intermittently began to lose hydraulics, with occasional shuddering and air banging around in the lines. No amount to extending/retracting of the cylinders would clear them out. I have changed fluids on this tractor before and never had this problem. It feels like air is being sucked into the lines somewhere, but hoses and lines look tight.

I am not very familiar with hydraulics and would be grateful for a point in the right direction to troubleshoot this problem.

Many thanks,
Richard

 

[kennyd]

Welcome to TBN

Two things come to mind...A leak on the SUCTION side of the pump causing the pump to suck air and cavitate, or the pump is just plian shot and when it warms up will not build pressure.

 

[Wayne County Hose]

Welcome to TBN. I'll bet you wish that you could have come here in a better situation. The only thing that makes me doubt a suction problem is that it comes and goes all of the sudden intermittently. Am I correct in this assumption? I would check the pump coupler. Or, start up and run, run one of the cylinders to full extension or retraction and hold the valve for a couple seconds, making the pump really work. Any strange noises you never heard before? This also checks the pump coupler, kinda. Or, a bad pump like Kenny said.

 

[kennyd]

Good thought on the coupler Andy, I forgot the older machines use a external pump driven through a Lovejoy or similar coupler. I am used to the newer machines...

 

[JD300]

Many thanks for the quick responses!

Sometimes the machine runs normally. It has plenty of hydraulic power, plenty of bucket lift. It can easily lift the tractor with down pressure with either the front loader or backhoe. It can run this way for minutes. When it is running normally, it sounds normal. This makes me think the pump is okay.

Then, suddenly, no pressure. If a bucket happens to be up, it stays up until you put it down. Then nothing. At this point, it still sounds normal, no click-click-click like it is out of oil. If you hold a valve open, no pressure, no funny noises. It can be like this for minutes at a time. RPM doesn't help. Then, sometimes, the cylinder will start to move, slowly as it builds up pressure. Sometimes the whole tractor will shutter loudly as the cylinder ratchets up. You can hear air pinging around in the lines. Sometimes, after shuddering for a few seconds, the pump will "catch" and pressure and operation will be normal for a minuter, or so. Then, it goes off-line again.

The problem seems to more related to the loader than the backhoe. In fact, when the loader cylinders are "dead", if you open the backhoe valves and move the backhoe pistons a bit, you can restore pressure to the loader for a while. The tractor itself always has moved forward and back on its own.

It does seem like an air suction problem, but I am not sure.
Richard

 

[Wayne County Hose]

Good thought on the coupler Andy, I forgot the older machines use a external pump driven through a Lovejoy or similar coupler. I am used to the newer machines...

....And I am used to the older stuff. I can't afford newer.

This does sound like either a pump or something on the suction side, as Kenny has said. Almost sounds like cavitation. I doubt that the pump coupler is the culprit. You better fix it soon before your pump grenades.

 

[true temper]

Did you get your 300 fixed? How about the power steering, is it working? If it is working your priority valve is stuck. The valve is located on the side of transmission above the filter housing. If there is a problem with it the back hoe and steering will work but not the loader.

 

[Rara Avis]

Many thanks for the quick responses!

Sometimes the machine runs normally. It has plenty of hydraulic power, plenty of bucket lift. It can easily lift the tractor with down pressure with either the front loader or backhoe. It can run this way for minutes. When it is running normally, it sounds normal. This makes me think the pump is okay.

Then, suddenly, no pressure. If a bucket happens to be up, it stays up until you put it down. Then nothing. At this point, it still sounds normal, no click-click-click like it is out of oil. If you hold a valve open, no pressure, no funny noises. It can be like this for minutes at a time. RPM doesn't help. Then, sometimes, the cylinder will start to move, slowly as it builds up pressure. Sometimes the whole tractor will shutter loudly as the cylinder ratchets up. You can hear air pinging around in the lines. Sometimes, after shuddering for a few seconds, the pump will "catch" and pressure and operation will be normal for a minuter, or so. Then, it goes off-line again.

The problem seems to more related to the loader than the backhoe. In fact, when the loader cylinders are "dead", if you open the backhoe valves and move the backhoe pistons a bit, you can restore pressure to the loader for a while. The tractor itself always has moved forward and back on its own.

It does seem like an air suction problem, but I am not sure.
Richard

NO Hydraulic Functions
1. Check hydraulic oil level, type and viscosity.
2. Check suction line for air leaks.
3. Hydraulic pump seals leaking including pump shaft seal.
4. Check for plugged reservior screen and vent.
5. Check for damaged or missing pump coupler.
6. Hydraulic pump damaged(scored or worn)
7. System relief valve stuck open.
8. Cracked flow divider housing.

 

[JD300]

<<<<Did you get your 300 fixed? How about the power steering, is it working? If it is working your priority valve is stuck. The valve is located on the side of transmission above the filter housing. If there is a problem with it the back hoe and steering will work but not the loader.>>>

Not yet! The tractor is about 100 miles from my house. I'll have another crack at it this weekend. When the hydraulics go offline, I am pretty sure the power steering is dead too. Also, when the loader dies, the backhoe cylinders are dead too. Where is the priority valve? My parts book does not show it.

Two possibilities, both on the right side of the transmission case above the loader return oil filter:

1. a part bolted to the side of the transmission case with about 4 oil lines going to it, and with a relief valve, or

2. A plug by the floorboard, by your right heel, on the side of the transmission case. My parts book shows a spring behind this, like it is some type of pressure valve, but the parts inside are stuck in when I removed the outside plug.

I appreciate your help. I am lost without my handy little backhoe!

 

[JD300]

<<<<<NO Hydraulic Functions
1. Check hydraulic oil level, type and viscosity.
2. Check suction line for air leaks.
3. Hydraulic pump seals leaking including pump shaft seal.
4. Check for plugged reservior screen and vent.
5. Check for damaged or missing pump coupler.
6. Hydraulic pump damaged(scored or worn)
7. System relief valve stuck open.
8. Cracked flow divider housing.
__________________
Paul in VT>>>>>>

Where is the System relief valve located? There are several plugs on the transmission and oil filters which have spring-loaded valves behind them. Also, there is a plug by the floorboard, by your right heel, on the right side of the transmission case. My parts book shows a spring and some other parts behind this, like it is some type of pressure valve, but the parts inside are stuck in when I removed the outside plug. Is this the system relief valve?

Many thanks!

 

[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.