I have an old 1974 310 John Deere Backhoe that I use on my small farm with slow hydraulics. I can move one cylinder at a time just fine, but add in a second cylinder and the movements become very slow. It's much faster to make the movements one at a time, rather than try to make compound moves. I removed the return line from the backhoe control valves and started the engine (per the tech manual) and have LOTS of oil trying to return to sump. Strickly a guess, but maybe 3-5 gallons a minute. So the questions: (1) Is there another test I can do to isolate the problem to the bad valve or valves? (2) Or is it likely that all 6 valves have enough wear (6200 hours on the machine) that they all need rebuilding? (3) Will putting in an o-ring kit usually fix a problem like this or am I looking at having a more costly rebuild? (4) Will running the machine just the way it is cause any damage to the rest of the hydraulic system? It digs just fine, just can't make two moves at once.
The first thing that I would do in this situation would be to call a dealer and find the correct flow spec. You didn't mention the rpm at which you did your "test" but this has to be done at a specified rpm and pressure to determine exactly what you have. 3-5 gpm is more in the order of a power steering on small machines than main hydraulics. If you do your test at rated rpm and the open ended flow is to little I would look at possibly a partially restricted pick up screen in the reservoir, a collapsing pick up line, or just the pump getting old. Also look to see if you have a diverter/priority valve that may be allowing excess flow around the valve. Just a few things to try.
Thanks BillG, I did the test at idle and just for a few seconds. The manual led me to believe there shouldn't be any oil coming out of the main return line port right at the valve bank. This is the big hose that routes oil back through the filter and then to sump. I should have mentioned that the pump has just been rebuilt and the screen cleaned, and filters have all been changed and all new oil.
What was it like before the pump was rebuilt ?
Exactly the same. The shaft seal went out. Installed a new pump shaft and seals kit and that part seems good as new. I've only owned this for a couple of months and it's my first experience with a backhoe so not really sure if this is a problem that has come on gradually over the years or started all of a sudden. But it has been this way ever since I've had it. It works okay except for slow motion when making multiple moves. I've removed over 50 stumps and dug around 400 feet of ditch, so it's quite usable. Just can't do two things at once.
Do the functions have good lifting/digging power when you're operating one function at a time?
Willie59, Yes, the lifting/digging power seems fine when moving just one function. If I'm moving just the boom up or down, or swinging right or left, or curling the bucket, it seems fine. Try to do any of those two things together (or any other two movements) things come to a near stop.
If my mind is not failing me these use a charge pump to supply oil from the sump to the main pump. Most likely you are not getting enough oil to the main pump. I will try to search for an old thread similar to this.
It does use a charge pump to feed the main pump. But why am I leaking oil past the 6 control valves that control the backhoe? Oil is getting to the valves no problem. I think I've isolated the problem to the valve bank. It is my understanding that oil is not supposed to get past the valves when they are in their neutral position. I'm loosing oil past these valves. I disconected the hose from the control valves that returns oil to the sump, and with the engine running for just a few seconds I had a gusher of oil coming out. I think if I fix what ever is causing all this oil to get past the control valves when they are in their neutral position I will have solved my problem. I'm just wondering if a seals kit usually does the trick or if I'm looking at a more costly rebuild.
I have owner a similar machine. It was a 1981 410 but I am NO hydraulic expert. But I think there are hydraulic valves that are called POWER BEYOND. Does that term not mean that flow and pressure needs to travel through the valve? Your machine like mine, should have a piston type main hydraulic pump. It may use a power beyond system so as not to deadhead the pump when no functions are used. Like I said, I don't really know what I am talking about but something your manual may confirm. One thing I do remember about the old 410 is that the hydraulics were very strong even at dead idle but it was quite slow compared to newer machines. Is it also very slow while doubling the functions when your engine is running at 1,800 rpm?
Deon, Maybe this backhoe works normally then. This is my first time on a backhoe, so not really sure how things are supposed to be. I can live with it the way it is. It has good power, just slow on compound movements. Below is the text right out of the Tech Manual. I did this test and I have oil leaking out the return. Lots of oil, so I'm thinking I have spool leakage. TESTING CONTROL VALVE The control valve spools may be worn, allowing oil to leak past them. Check the control valve for leaks as follows: 1. Place backhoe control valve in neutral and disconnect the return line between control valve and reservoir. 2. With the control valve in neutral, start unit and check for oil leakage past the valve spools. Oil will leak out the return line if there is spool leakage.
chroniekon, If that is what is written in you service manual then it seems you have leakage. You will probably need a seal kit and replace all the seals. Hope all works out.
chroniekon, you have a very strange problem. I know very little about the Deere loader/hoe hydraulic system configuration, and even less about one of this vintage. But what I can tell from the parts pages is the 310 of this vintage (I'm guessing it's a 310A) used a positive displacement piston pump, not a hydrostatic pump. It doesn't have any de-stroke valves or solenoids, nor does it have the manual de-stroke valve for cold start up. My point is, given the charge pump is supplying oil to it, if it's turning, it's pumping oil. Just a best guess on my part, but logic tends to tell me that if any single function of backhoe works with good speed and good power, then the charge pump is supplying sufficient oil to main pump. Otherwise you would notice something jerky in working even a single function. Also, you haven't mentioned steering or front loader functions, so I take it that means they are working fine, is that right? If that's the case, this tends to indicate the pump is operating as it should and the problem is isolated to the backhoe control valve. Now I may not be spot on with the Deere hyd circuit, but most loader/hoes of this type work something like this; pressurized oil leaves the main pump and goes to a priority valve, I think it's called a pressure control valve on this unit. The priority valve makes sure that oil is always available for steering, like when you're driving the machine forward while raising the front loader with a load. In this scenario, the demand of raising a loaded bucket would rob all the oil and cause steering to be hard. The priority valve makes sure oil keeps going to steering valve in this situation. So the priority valve tee's off the main supply line and goes to steering valve and loader control valve. The steering valve is a closed center valve, and the loader control valve is a closed center valve with power beyond going to backhoe control valve, which is closed center as well. We can assume this is the way it's configured as you said the manual states that no oil should be coming out of backhoe valve tank port when valve is in neutral. Since the steering orbit valve and backhoe control valve are closed center, they create a hyd dead end when valves are in neutral. We now have nowhere for the oil flow from pump to go, and since it's a positive displacement pump, there's going to be a hyd explosion. This is the other function of the pressure control valve; when no functions are being operated, it dumps oil being delivered from pump back to tank. As soon as you operate a function, whether it's steering, loader valve, or backhoe valve, the pressure control valve stops returning oil to tank and instead delivers oil to the function being operated. Now to your problem. If the steering and front loader is working proper, and problem only exists when operating backhoe functions, then that's where it gets very curious. I say this because I'm thinking it should be a closed center valve chest, it should not be possible for oil to come from tank port when valve sections are in neutral. Add to this, as I view the parts diagrams of a 310A, these valve sections have internal power beyond ports to supply oil to each section to supply oil to other valve sections when a single function is being operated. This type of valve does not incorporate internal power beyond that uses poppet valves (one way check valves), so poppet leakage/failure cannot be your problem. These valve sections are a very simple internal ported power beyond. That basically means when you operate a single function, it's going to supply oil to other circuits as well, the fact that yours is not doing that is curious indeed. Add to this that you have oil coming from tank port when valve is in neutral, then you have a very odd problem. As I view parts diagrams, I don't see many things that could typically cause this problem. I find it highly unlikely that all of the valves are worn slap out to the point you have that much internal leakage, I have never seen a whole valve body worn out that bad and still have good power for each function worked individually. That just doesn't make logical sense. Likewise, I can't see where seals would be the problem. Valve spools don't have seals on the internal workings, they only have seals to prevent leakage externally, such as where the spools stick out of valve section on each end. If they were bad, you would see external oil leaks and would have no affect with oil coming from tank port. There's only one thing that I can see that would cause your problem, and I'm not certain it's a workable theory, but I'm wondering if someone in the past has pulled all the valve spools from each section and has re-installed them in a mixed up manner. The two stabilizer valve sections are the same and use the same spool, but the boom, arm, bucket, and swing all have different valve spools and are not interchangeable. I'm wondering if these spools are now mixed up. I will admit, I've never seen someone do this before, and I'm not certain this would be the result, I'm just trying to think of anything that would cause your problem, and I'm just not seeing anything else that would cause what your describing. I certainly hope you find out what the problem is because now I'm curious as hell as to what it is.
Willie59, Thanks for the response, you've obviously put some time and thought into this matter. It's much appreciated! Not sure if it changes anything you're talking about in the way this system works, but here is the kind of pump I have as described in the first two paragraghs from the hydraulic pump section of the manual, it reads as follows: The main hydraulic pump is an eight-piston, varia- ble displacement, constant pressure, radial piston type. The pump is equipped with a pilot-operated poppet- type solenoid valve located in the hydraulic pump stroke control valve housing. The solenoid is normally closed and is electrically opened during engine cranking to bypass discharge oil directly to the pump crankcase. Also, it is a 1974 310. I think the 310A came out in 1975. I agree, from everything I have read, the charge pump is working okay. Single functions are good and no chattering or jerking. However, you might be on to something here because the front loader works the same as the backhoe, in that it will go up just fine or tilt the bucket just fine, but it moves very slowly if I try to tilt the bucket up or down while raising or lowering the loader. Single function good, multiple function not good. It seems unlikely that the loader valve stack would have the same problem as the backhoe valve stack. The steering is a little weak if I raise the loader and turn at the same time, but only if the engine is idleing. Anything above idle and it's fine.
Are you digging at idle or full throttle?
Then I would suspect that the pressure control valve isn't delivering oil properly. But, that still doesn't explain oil coming from the tank port of backhoe valve when valve sections are in neutral. Very perplexing problem.
I'm going to look into your idea that the spool valves are mixed up. Hoping it's only two spools swapped. I'm wondering if I can isolate the problem valves by diconnecting the hoses that go to the individual cylinders one at a time? I'm suspect of the priority valve too. I looked it up in the manual, and I should be able to steer easily while using the loader, even at idle.
He's still gonna have standby pressure going through the valve...I'd expect around 300 psi (dont have my manuals with me) Once again,what engine speed is the OP trying to run the machine at? Older deere backhoes do not multifunction well at lower rpms....not enough flow.
I've been digging around half throttle.
crank 'er up buddy...full twist fer digging! With the age of the machine,your pump is probably somewhat worn out(you had it resealed,not rebuilt),but without having it flowtested,there is no way to know. In a simple sense though,look at it this way: Lets say that at 1/2 throttle,your pump is making 5 gallons/minute at 3000 psi Suppose that your boom cyl is gonna use 3/4 of that flow when you pull the lever Add in the crowd cyl,which will want near the same flow we're now at 1.5 times the capacity of the pump at that speed. Get more flow...spin that pump faster.
Cutting edge could be right. My 1981 410 also had slow backhoe movements when using two functions simultaneously. I know its suppose to divide the flow in two but at half throttle if feels like things are crawling. The worst about those old machines is the motor, hydraulic pumps and everything else is very noisy and the cab if you have one is not isolated from the frame of the machine so its quite deafening so you tend to run the motor slower. Put ear protection on, crank throttle to at least 2000 rpm and try it out.
I had a 310 like yours and it had the 8 piston pump variable displacement, with the solenoid valve to allow the motor to crank without building up pressure in the pump. The hydraulic problem I had was the main boom got lazy after the oil warmed up and was slow to lift. Problem was a bad O ring on the solenoid valve. I sure was glad to find that bad O ring, otherwise the next step was to replace the pump. The 310 does have a priority valve which gives flow to either the loader or backhoe depending on which is used. This is a common component as you said you have the same problem whether you use the loader or the backhoe. When you say you rebuilt the pump was it a complete rebuild or just a repair of the input shaft. If you only repaired the pump I wonder if there is a problem with the swash plate in the pump. You seem to have adequate pressure ("digs well") but a fixed amount of flow which lets you use one function but is not enough for two. Perhaps your leaking backhoe valve is bypassing enough oil flow that all you have left is enough for one other function. Normal operation is that speed will slow down, the more functions that are used due to the capacity of the hyd. pump, but should not drastically slow down when using only two functions. An operator can be using up to 4 functions at a time with the two control levers for the backhoe. Keep us posted.
It's going to be a few days before I can get back to this project, but I'll let you all know what I find.
So I got back to the 310 today. I checked all the spools in the backhoe control valves and everthing matches the parts drawings. I don't see anything with excessive wear in there that would account for the oil leakage. So everthing back together and a trial run. I have never run this thing at full throttle because I'm new at the controls, and lets face it, I suck at it, (but I still can't wipe the smile off my face) But that really makes a difference! I don't think it's perfect, but absolutly acceptable for my hobby farm. Thanks to all of you that helped out. I've been checking in here every so often just trying to learn as much as I can from the guys that make their living with this equipment and their is a treasure trove of information here. I'm sure I'll be stopping in for help from time to time.
thumbs up!