I'm new to this forum and to this machine. All functions work well but the dipperstick has very little power. Meaning it will move with no load and the engine pulls down slightly when it does. But but when I have even a half a bucket it will not crowd, even in loose soil. I have checked pressure at the cylinder and it is 2550 lbs. The engine rpm does not pull down at all. It is as though all the pressure is somehow bypassing actually pushing the load. How is this possible? There are no leaks in the cylinder. As an aside, when I try to use the crowd function, the curl function power also is greatly reduced. Meaning anytime I am curling the buckat and try to crowd, the bucket curl stops until I let go of the crowd. Machine has 5300 hours. I had dealer come out, they checked pressure at pump, control valves and cylinder. We changed the filter, it was clean. It is driving me crazy as this is a nice machine, but I cant do squat with it.
could it be a bad seal in the cylinder?
So what did the dealer think was wrong? since they did the testing. Did you have the line at the cylinder dead ended to the gauge, or teed into the gauge? Neither way is making a lot of sense to me but it would help to know. Also, how does the stick extend function work? Do you know how a closed center hydraulic system works? when a function is stalled the pump acts just like the valve is closed. The pump only loads the engine when oil is flowing.
The dealer says he didn't think so because the wiper seal would probably be leaking. it was teed in to the gauge No I didn't but now I do. That makes sense and this one is certainly doing that. Whether I move the stick 1/8 or the whole travel, it has the same power. It isnt pushing or pulling with any strength. Here is the rub. He says that the 1999 machine is too old and that no-one at their shop has worked on 710's. After he went to the JD online help and found nothing beyond what he tried, he had no further suggestions. I did talk to an old timer at a private repair shop and he though it might be the spool valve in the dipperstick control valve just bypassing all the fluid. A big job to repair and they are not rebuildable and no individual valves are available new. Used I can only find a very expensive complete used 6 valve set. The e stick works fine, I tried moving it to see if it was hanging up something but it made no difference. Thank you for helping
E stick? do you mean you have an extendahoe? I meant does the stick go back out with normal power when the crowd cylinder retracts?
Yes it has extendahoe. I will check extendahoe when I crowd.
So you do mean the dipper has no power either way. And the dealer who is incapable of fixing one of the simplest hydraulic systems doesn't think a piston seal can leak without the gland seal leaking. So based on that contradictory reasoning, I have no idea what's going on. Further diagnostic steps would be to swap the hoses and see if the problem moves to the curl or stays with the stick cylinder. Or starting with a cold machine, hold the stick stalled for 10 seconds, hop down and see if the valve section or the cylinder where the piston is are warm to the touch. If you can't find any warm spot, try it for 20 seconds. Don't bother with the extendahoe, I think I understand the problem. Did the "tech" check the charge pressure, or the transmission screen?
Yes, there is no power either way. Apparently, but you have me questioning that! That is a REALLY good idea, sheesh Ok I'll do that. Stupid question alert... Should the oil should be warm first? Or will it get warm to the touch even with cold oil? If so, would stalling( or moving) the front bucket warm the oil? I dont know what this is, but he only checked the pressures I mentioned above. Is the charge pressure coming into the main hyd pump from the charge pump? Funny you should ask this. No he did not check anything to do with the transmission. Should I do this? Can you explain the thought process here? The machines automatic seems to shift well, but it feels like the engine is not getting proper fuel as it will not rev to the limiter on a smooth road (it will in neuteral when I'm running the backhoe) except in 1st or 2nd. It bogs down in 3rd at 2000 and 4th at 1500 rpm. I'm installing a new lift pump today as the fuel output from a clean filter seems really weak. I'm not sure if low engine power is contributing to the Hyd isue, but it seems best to fix that first and then keep moving on the Hyd. Are you suggesting I clean the tranny screen too? Thank you for your ideas and suggestions. "Tech" was there for 5 hours and when the bill hit a grand I had enough. He said I should have it brought to his shop and expect to spend 4-5 grand to diagnose and fix what ever it is.
You do have 8 forward speeds right? bogging in 3rd The lift pump is probably cheap, at least compared to the tech, so it can't hurt. They typically leak, not get weak, but you could have gunk in the valves making it weak. When it doesn't help, check the screen in the tank. Does the lift pump priming lever seem to have decent resistance? it shouldn't, it should pump fairly easily. You can try removing the hoses and using the priming lever with temporary hoses in a can of fuel to get a feel for what it feels like when there is no restriction on the inlet or outlet, then use your finger to plug each and compare. When it's pulling a vacuum, the lever gets harder to operate. I might be off on the transmission. Some JD had the transmission supply the charge pressure oil to the hydraulic pump, and the charge pressure was third in line for priority if anything's left over. Too bad Lantraxco's not around here anymore, he was good at remembering which model did what. Do you have a separate charge pump on the front of the engine? An Operation and Test Technical Manual is priceless in this situation, if we don't figure this out easily. If you wait for the perfect crisp frosty morning, I'd bet you could make it "steam" from the affected spot with the sunrise in the background. A thermal imaging camera would find it at whatever temp, or a infrared thermometer if you have the patience. I thought cold because you can feel the difference between 50 and 150 much more quickly than the difference between 150 and 250. Even a heavy dew might make it visible, I was only half kidding. Stalling a function will not heat the oil, it just sits there the same as with the valves closed, the book procedure for warming the oil for testing purposes is to loop a hose back so you BYPASS a cylinder and activate that function, high flow low resistance makes more heat than working it "heavy".
This is a 710D and has an automatic transmission, 4 speeds on the column shift. The lever does not pump any fuel at all. Its going to take me a while to make up hoses to swap curl and crowd. I am not certain if both circuits are closed loop, I have to check on that.
Oh, I was thinking of a different transmission, third bogging is still a little odd, does it blow some black smoke when it bogs? You don't have to swap both, if you hook up the crowd cylinder to the bucket curl hoses you can tell if the cylinder is leaking. They're all closed center valves, the worst you can do is leak some fluid, wait, no, don't block off the rod side of a cylinder, that could blow up. It looks like you might be able to switch the hoses at the valves easier than most backhoes too. Especially if you can get ahold of some good crowfoot wrenches in the right sizes. Label them first of course. I'd still investigate the transfer pump, see if it will pump from a can, blow it out with air, or a garden hose, you won't hurt it if it's already broke. I like to see how things broke so I'd pull it apart if all else fails.
If the rest of the hyd systems work ok and you have that kinda pressure at the cylinder it's leaking past the gland seal most likely, i have seen cylinders so bad that they would stall out and not leak around wiper seals, matter of fact just replaced boom cylinder because of that problem it fixed it and it was only leaking a couple of drops around wiper seal, worth a shot.
Another simple test is dig the bucket into the ground a bit with the stick as straight as possible then with the wheels on the ground at a low idle in first gear will it move the stick at all and if so how much going both forward and reverse. You can also just fasten the bucket to something immovable but depending on what you see the cylinder and rod doing can tell you a lot. One other thing nobody has mentioned is are you sure the boom/stick pin isn't seized... haven't seen it happen on a 710 but have seen it on other stuff.
Does the stick drift down if you raise boom and push stick out level to the ground and leave there?
Another option, bury the bucket so the stick won't move. Remove the rod side hose and cap the HOSE. Start it back up and try to crowd the stick, if oil continues to leak then the piston seals are leaking. It will shoot some oil as it takes up the slack, but should hold after that as long as the cylinder doesn't move.
Thanks for the replies. We have determined it is NOT bad cylinders. Curl and crowd are bith no good, so swapping them makes no difference. I'm going to restate with the direction we are now looking. I have a 1999 John Deere 710D with ( im pretty sure ) closed center control valves. It appears to be a radial type of pump, the pistons are just touching until the system senses the load and the piston stroke is fully activated. I'm not sure if it has a sequence valve (I assume it does) , but it also has a electric solenoid to destroke the pump when the engine is starting and there is no pressure. The problem is I have 2550 lbs inline pressure on a gauge at the cylinder for the curl and crowd (and hydraulic valve port) but there is simply no POWER. It barely digs or crowds (500 lbs) , but it should be a monster, with 9500 lbs crowd force. As I move the sticks I can briefly hear the engine slightly load, but suddenly unloads when I need it to dig and wont crowd or curl anymore and the engine has no load. I don't feel or hear any bypass at my feet. At this point the cylinder pressure is 2550 lbs on an inline gauge. So it is though the pump senses the 2550 lbs and thinks it should destroke the pistons and stops pumping but still just keeps the minimal destroked pressure?? Even when I bring another valve like the boom ( which does have some power, but I cant tell if it is a lot or a bit because I cant dig enough with the curl and crowd to make a trench) !to require fluid flow, this flow does not activate any more power to the RH stick as I thought it might if the pump had destroked. As long as there is no load, the stick functions work as normal, but as soon as I need digging force the cylinders stall and the engine unloads. I unhooked the start electric destroke to assure it wasn't kicking in, but it made no difference. Could the pump just be worn out and when the sequence valve kicks in, it activates the full strokes and 2550 lbs but with a bunch of leakage at the excentric center it just doesnt send any power to the cylinders? I've brought out several different JD repair people and there just isn't some obvious solution. We are still trying though. They all agree there is simply no digging force. Hopefully someone out there HAS a 710D or worked on one with this problem or I think I am screw$d.
Have you done a flow test to see if you may have a restriction in the return ,or lack of flow from pressure side?
Yeah, this is weird and getting weirder. What's the history of this? how long have you owned it, how long has it done this, did the curl change or did you not notice it originally? Also, did you swap them? Does the loader work right?
Flow test is in the works. Hopefully it shows something. What should I be looking for? I recently bought it on the assertions of a respected dealer that everything functioned correctly. I was not able to personally test run it before it was delivered. The very first time I ran it ( curl and crowd) I knew there was a serious problem. I use a 410B and know the 710 should outperform it ( at least on specs). The 710 has less power than my Kubota! Swapping hoses wont show anything as they are both weak. I have lifted buckets of loose soil with the front end and it seemed to do OK for that, but I haven't put it into compacted soil to see how it digs or lifted concrete or rocks or anything really heavy yet. I need the backhoe to work to really put the loader to work. We bought it for the backhoes power to break shale with a bigger bucket. It wont even scrape 4 inches deep with a 18" bucket. The 410 has no problem filling a 24" bucket. Pathetic.
Before a flow test, I'd do the tests in #7, #9, #15. Force is pressure (which you HAVE???) flow is speed which you can measure by extending all the way out and bringing all the way back in, boom, stick and bucket from out to curled in. I'm thinking like 12 seconds, but see if you can find that spec. Does the boom, stabilizers and loader bucket each lift the machine on their own? "As I move the sticks I can briefly hear the engine slightly load, but suddenly unloads when I need it to dig and wont crowd or curl anymore and the engine has no load. I don't feel or hear any bypass at my feet. At this point the cylinder pressure is 2550 lbs on an inline gauge. So it is though the pump senses the 2550 lbs and thinks it should destroke the pistons and stops pumping but still just keeps the minimal destroked pressure?? Even when I bring another valve like the boom ( which does have some power, but I cant tell if it is a lot or a bit because I cant dig enough with the curl and crowd to make a trench) !to require fluid flow, this flow does not activate any more power to the RH stick as I thought it might if the pump had destroked. As long as there is no load, the stick functions work as normal, but as soon as I need digging force the cylinders stall and the engine unloads." This is all exactly as it should function at full pressure. You have full pressure measured at the cylinders, either the cylinders are leaking (which would heat up that spot fast, and load the engine), or there is huge backpressure on the other end of the cylinder (you can measure that easy enough), there is NO other possibility (well, the siezed pin, but you'd hear that squeeling right). It might not be up to your expectations.
You are as frustrated as I am. I'm stating what we see, and what the machine is doing and trying to find someone that has seen the same thing and knows how it occurred. There have been a bunch of pretty smart guys that are trying to help in the field, this is not an obvious fix or they would already have repaired it. I keep getting told it must be something simple that we are overlooking. Every single tester gets this. Every single tester has come to the field and thought they would fix it knowing pressure equals force. Then they operated the machine. It is not a matter of it producing 7000 lbs of crowd and I expect 9000, it doesnt produce 500. They move the sticks, we see pressures and the parts dont move with a load. It isnt a matter of expectations or operator skill. Skilled repair people have spent hours and hours on this. I half expect them to give up, but they haven't yet. It appears that the leakage is happening, we cant figure out where. It is not at the cylinders, but we are going to check this a third time. The flow timing is fine when there is no load. The boom functions are all normal. Once there is a load, the flow stops or is being diverted. Perhaps some small amount must be getting through to make the pressure we see, but not enough to move the parts (or something). I'll try to make a video and let you see. Everyone sees the pressure and wonders why it wont dig. We are going to bring it to the shop and do the flow test of the pump, and tee the cr@p out of it to try to figure out what is going on. All of us agree ( except the seller) that I should just get my money back. Before I go down that route I'm on here looking for someone that has seen this on a 710D before.
This is a little off the wall . Had a flow problem with a dozer once ,ended up hose separated internally and blocked flow.
I have no history with a 710 but I feel your pain. I belive there are a few reasons you haven't gotten many answers about the 710 specifically. I believe not many smaller outfits bought these units, they certainly were never a "popular" machine due to its size, and the ones I've seen have been owned mostly by municipalities, typically if they have a problem, they send it to the dealer and if the dealer can't fix it I feel the municipality simply "lives" with the problem or the dealer does fix it and no one ever gets an answer to what the problem was. I am certainly no mechanic, but it sounds like you have a relief valve stuck or not functioning properly. Like Delmer said, bypass creates heat, run it a bit and check all valves and lines with a thermal gun right back to the pump. Hopefully a flow test shows what your issue is... On a side note, if you search "710" in the Backhoe forum I belive you will find a thread by Workshoprat, he was looking at 710s a while ago and felt the ones he looked at had no power either....could be a common issue with 710s
Measure the other end of the cylinder pressure, seems off the wall but that's the only logical explanation left. Rag, or hose cap wedged in the control valve, it's happened before... I wonder what the selling dealer replaced recently??? There's no point in measuring flow, the pump does not care what is blocking the flow, it pumps only when the pressure drops below standby, stops when the pressure comes back up. This is not a pump unique to the 710, the same functional design was used from the early 60's in nearly every tractor, skidder, dozer etc. that JD made. You'll wait a LOOOOOOOOOOOOOONG time to find somebody who has had this problem in a 710d. I don't think that's necessary, there's no sequencing valves, pilot pressure, computer pump controller etc. The priority valve on all similar jd's only blocks flow to the loader to save pressure for the brakes and steering. I'm not AWARE of any functional difference in the 710 vs 410-510-610 hydraulics.
Thank you Delmer and Tags. Yes, had I known about these issues I would not have bought it without a thorough test run. I did not know it wasn't popular due to power issues, only that it was too heavy at 29000 lbs to be transported via a trailer and dually. One person said that the 710 was unique in the way it distributed flow, but I cant find anything to back that up. One of the JD Etech theories was that when the dipper was past 90 degrees, it was loading the boom as it crowded and raising the pressure of the boom above 2450 causing the boom to destroke the pump (since it had priority). There were two fixes suggested, one was to slightly raise the boom to reduce the pressure, thereby restroking the pump and giving the flow back to the dipper. This essentially makes the operator the compensator. I tried that but it made no difference to the force available. If it had worked, the suggestion was to change the relief valve to 2000 lbs, but since this manually relieving the pressure did not work, it isnt the problem. I wanted to mention this so if someone else is following this thread at a later time, they know we tried this.
Searched for workshoprat 710 and found a lot of posts but nothing on the 710. Can you point me in the right direction? Found it, thanks. HeavyEquipmentForums Yes, the one he was looking at had this issue: >The hydraulics are weak. All the functions run and work but do not work with power. for example when you lower the outriggers they touch the ground lift the machine a slight little bit then quit. when you hold the control and bottom a function the engine does not bog down or do you hear a relief blowing by.The other two options are that either the pump is cutting out at too low a pressure, or the charge pump system is not working and the pump can't get enough oil to push out? Oh, third thing that silly priority valve Deere uses in these systems< I would like more information on the priority valve as the etech pointed to that. Delmer, you are saying there is no priority to the backhoe control valves, only to the front loader? No wonder that unloading the boom made no difference. Another dead end. I'm going to take my laser temp and check heat too. Sure hope we figure this out so the next poor guy has some direction, but I'm having my doubts now.
You say "I think good boom an loader power" you need to verify this in one way or another. The loader should lift 7700lbs to full height, do you have anything close to that heavy you can chain the bucket to? When the hoe is extended fully will the boom lift? It should lift almost 1700lbs with the boom cylinder, extended straight out (extendahoe). Can you lift the rear of the machine off the ground with the hoe? Looking at the parts catalog there was an option for controlled load lowering on the boom and stick cyls, does your machine have these valves? They're mounted on the cylinders. Also that theory on the boom pressure getting raised from the stick causing the pump to destroke... The individual circuit relief valves are there to protect against over pressure from such forces, nothing to do with pump control.
To give you an idea of the capacity this machine should have, the manual shows between 4900 and 7400 pounds of dipper stick lifting force with the boom at 65 degrees. It also has between 2700 and 3500 lbs of lifting force on the boom alone with the dipperstick fully up. It should have over 12900 lbs of force in curl. These are really big numbers, so to have so little force right now something should be readily evident. Although implausible, I'm beginning to think that perhaps all the pressure relief valves for crowd and curl are completely worn out and bypassing as such a low force that I cant hear it. I might remove them and have them tested. THAT would be a great fix! Any thoughts so on that idea? Will they heat up if the release pressure is low and all that fluid is forced through them?
I got those lifting specs from this PDF brochure, it's easy to test lifting capacity, not so much for digging power. It's obviously lacking, but you need to verify if it's just one function or all functions that are weak.
Absolutely right. I have not tried to verify the boom or loader. I do have a 2500 block of concrete I'll start with that which is pretty close to what the boom alone will lift with the dipperstick out, estick in. The loader bucket should easily lift it ( I think it lifts 7700 lbs to full height) as well. If it does I have several more I can add.
I'll check, but not that anyone has pointed out..
I was wondering about this because I could not find any way, such as electrical, for a signal to get to the destroke side of the pump to deactivate it. Plus the crowd has to be more powerful than the boom, otherwise every time you tried to boom, the crowd would release. The boom pressure and angle geometry allows for a very powerful crowd force.
Yes, easily with down boom. It "appears" the problems are in the RH stick only but I will quantify this with some lifting with the boom.
As far as I know, there is no priority in the backhoe valve, the "priority valve" mostly functions as a manifold to connect several hydraulic lines together. ONLY the front loader supply goes through the valve and is shut off to protect the steering and brakes. The backhoe works while driving around and using it will result in loss of steering and brake pressure. You can operate all four backhoe functions at the same time and the one with the least resistance will move fastest. Relief valves would make heat, they're not bypassing at low pressure because you have 2,500 PSI AT THE CYLINDER. The reliefs are set above system pressure (except maybe boom down?) or else the point of a closed center system would be eliminated.
I cant change what the gauge shows or what the cylinder doesnt do. I'm trying to reconcile the problem as we see it. What I meant is that perhaps there is pressure, but no flow. All the flow is going through the bypass. 2500 lbs with a syringe needle of flow isnt going to move 9000 lbs, or at least not a useful rate. Isn't that correct? So they should be getting hot if they are bypassing, but wont if they are not, right? I hope they are hot has heck although I cant see how they would flow as much as that Hyd pump puts out.
Flow makes pressure and pressure makes flow. If it was flowing a needles worth of oil against a cylinder it would move slowly at whatever pressure equaled the resistance. THIS pump will flow 50+ GPM at 2,000+ PSI if the cylinder will move, or 2,500 PSI at no flow if nothing will move. The needle flow will not make any PSI without resistance. You say you have pressure at the cylinder with it stalled and 500 lbs force, the only way this is possible is with backpressure on the other side of the cylinder. You don't even need a gauge to measure this, poke the hydraulic hose with a stick when the machine is running but the stick is hanging loose, it will have ~200PSI charge pressure and be nearly as soft as an empty hose. Now dig a hole and stall the stick and have somebody poke the hydraulic hose on the rod end of the cylinder again, it HAS to be stiff as a spring or your hydraulic readings are incorrect. NO if's, and's, but's, bypassing, flow or anything else. The priority valve DOES have a system relief in it, another place to look for heat if you suspect a bypassing leak, though I don't because of your pressure readings.
Jay i looked at buying a 710d and every single one of them i looked at had this problem. I finally talked to a guy that was very familiar with these machines and is a fleet mechanic for a power company in the st.louis area. What i was told was there are 4-5 components that can cause this condition. The 710d will go about 1800 to 2000 hrs and then it will develop this impediment. When it does you replace ALL of the 4-5 items that can cause this to the tune of about $5000. Then you got a machine for another 1800 to 2000 hrs and ya get to do it all again. I think this is why you see them at auction as they hit that point and the owner just wants to dump it and not put 5k in it! In the end I decided to stay well away from anything john deere. Seriously not impressed with thier machines, engineering, lack of knowedgeable service techs, crappy dealerships with crappy attitudes and how they consider a machine obsolete in ten years and drop all product support. Hope that helps. Im sure its not what you want to hear and I sure wish i had something better to tell ya.
Yea i dont see this statement as being correct. The thing that makes pressure is resistance to flow. Lack of resistance creates flow. All things in nature flow from high to low in the path of least resistance. This is the same hydraulically or electrically. Case in point. My portapower is capable of achieving 10,000 psi. But it has zero flow at any given pressure unless the pump is stroked. And then it is the weight of the load (resistance) acting on the square area of the piston that creates the pressure.
Jay looking at some of your replies on pressure but possibly no flow. Ok flow is only a factor of how fast you can move a load at a given pressure. Again to simplify it down i will ise my porta power explination. Porta powers are usually rated in tons of force. Ok whats that mean. Well a porta powers pump max capable pressure is 10k. The only thing in a hydraulic system that moves a load is the pressure acting on the square area of the pistion. So if a porta power is rated for ten ton it would have to have a piston area of 2 square inch. 10,000 psi multiplied by 2 squar inch equals 20,000 divided by 2000lbs equals ten ton. For the load to move there has to be difference in potential. Meaning you must have a force greater than the opposing force. When this happens you will have movement till the two opposing forces are equall and movement will stop. Ok so in my little porta power i know i can move great loads but i can only do it very slowly. Why. Because the small size of the pump piston needed to convert the mechanical advantage of the lever and the force being applied to it will only flow or displace a very small amount of fluid per each stroke no matter the pressure. The flow is purely a function of the cubic volume displaced by the piston per each stroke. The long and the short of it is the only way you would not have the power to move a load that any machine is supposed to be mathmatically capable of moving is by not having the pressure (difference in potential) to move that load. No wither its due to pump, system components, leaking piston seal or even a lack of engine power its purely a function of lack of pressure. The ability of that sytem to create flow only controls the load speed. Ok so you talk about putting a know quantity of weight on a funtion and see if the machine can move that load. In essence what you are doing is testing system pressure by using the end result of the mathmatical equation of pressure multiplied by area and then factoring in the mecanical advantage of the geometry of the machines designed leverage. Of couse a far easer and more accurate way to do this would be to put a pressure gauge on the hyd line that you are activating and running that function to is end point creating and infinate resistance. Pressure will build and will only stop when the systems pump and other system components reach thier max ability to create a pressure and can be read on the gauge. You either have full rated pressure or you dont.
Agreed, saying you have the pressure but not the flow is as incorrect as saying an alternator puts out enough volts but it's not making any amperage. If an alternator is at 14v and no amps, it's because the battery is charged and there's no draw. That's why you measure under load, if it's still 13v at idle with all the accessories on then it's fine.
Right you can have pressure but no flow!!!! Again like you say under load! The hyd system will either make full rated pressure or it wont under load. Now the pump may be flowing its ass off but your not getting full rated pressure to the function you are activating. This is because somewhere in the system it has found a path of least resistance and will take that. The total system pressure will only get as high as that path of least resistance will provide. In all that i have read i have not seen any mention of what full rated system pressure should be or if any messurements of this pressure has been taken at the actuation point where the pressure is needed.
Ok one other thing and this may be a stupid question but does your controll stick have alot of slop in them? Is there a million miles of movement before it actually starts to move the valve?
Also delmar did hit on something else i agree with. The only way you could have full rated pressure and not be able to move a load that is within the mathmatical capability of that machine to move is you have to have an opposing force reducing the avalible pressure differential to move the load. Like delmar says pressure on the other side of the piston. If you have 100 psi on one side and zero on the other you have 100 working psi avalible to multiply on the square area of the cylinder. If you have 100 psi one side and 50 the other you now only have 50psi to multiply on the area of the piston. Again you need to take the time to know what your pressures are and where. If you have a high pressure on the backside of the piston opposing sytem pressure on the front side than id start to suspect a control valve issue. Of course a restricted or crushed oil return line could cause the same effect.
Something else comes to mind re reading some of the posts and the talk about destroking the pump. From what i remember i learned about that system from when i was looking at buying one the destroking function is only for destroking or unloading the pump when starting so the pump does not put an un needed added load to the starter. This is acomplished with an electrically activated valve on the pump. This valve is part of the 4-5 components you change all at once!
Hey just one more as this thread is bringing up many memories about looking at this series of machine. To be very honest i have looked at well over 8 machines in the 710d. I have yet to find one that should perform the way i think it should. I had also come to the possible conclusion that the 710d really was just an under engineered dog! I have yet to find one machine or anyone who has had one say im wrong!
Im going to do the lift tests and have the different circuits flow tested and report back. Stand by...
Sounds like a good idea. My work here is done. Good luck.
Here is the information from todays tests. Concrete boxes are 2500 lbs. Measurements are from the stabilizer to the bucket teeth. Dipperstick at 13' should lift 6250, it JUST lifted 5000 Boom at 14' should lift 3530, it could NOT lift 2500 Bucket should lift 7700, couldn't lift 5000, but it could curl it. Curl couldn't even lift 5000, didnt try 2500 I don't know if 12500 lb breakout force is the same as lifting force. All was done at high idle, it didn't make any difference if I ran it faster So force was down all across the board. I bought some 3000 lb preassure gauges today, I'm going to T them all over the place. It is really going to **** me of if the JD tech's pressure gauge was inaccurate since all this drama was based on those readings. In the first photo, I could extend the e stick about 2 feet before the loader bucket came off the ground. But the dipperstick couldn't lift it if I sent it out at all. Testing dipperstick at 13'. Testing curl. Each box weighs approximately 2500 lbs +/- 100 Testing boom at 14' and 2500 lbs. It could not lift this. Should lift 3530 Testing bucket lift
That really makes me smile seeing the tests for some reason!
More testing. It appears that there is 2550 at the cylinders. Either 2550 is not enough to push the parts to their rated force (doubtful since this is the specs published and the force I have is so much lower) or somehow the spool valves/hydraulic controls/destroking function is working incorrectly and as soon as it sees 2550 it reduces the flow to an amount that simply cannot move the part. It has power, then it just stops, the stick functions (all of them) stop moving far below the ratings. This occurs whether you open the flow just a crack and let it move into the weight, or move into it full stroke. The function just stops, the stick is dead, except if you reverse it out. Even while one of them is stopped, you can still move the others, so the hydraulic pump will put out fluid. But any one of the functions, independently or in concert with others, will cease to move as soon as it gets to 2550 lbs, and on the way up to 2550 lbs it does not exert the force it should. Meaning at 2500, before it cuts off, it isn't moving 95% of its maximum strength. I tried lowering the pressure to 2400, it still cut off exactly the same way, just lifted less. Which makes sense, once a closed loop system sees no more flow, it cuts out. BUT THERE SHOULD STILL BE FLOW BECAUSE IT SHOULD NOT BE STALLING OUT! The next step is begin cranking up the pressure and see what, if anything, that does. Hopefully it doesn't blow seals. I think the cylinders are rated for 3000 lbs. I'm thinking there needs to be a bit or reserve PSI, sort of a cushion to keep the flow going so it works at 2550? I don't know. At 100 lbs less it doesn't lift close to capacity, I cant see what 100 more PSI is going to do. All the functions are 20 to 50% low on power, curl, crowd, boom, loader. I may get a 3000 psi electric hydraulic power pack and bypass the entire 710 hydraulic system. Put in my own valve and new hoses. Then see if the crowd or curl function will dig properly at 2550 lbs with a system that does not have a destroke closed loop system. At least then I would know the geometry and cylinders have the function and power that is advertised. That is going to be A HUGE amount of work. Perhaps I'll borrow a 410 and hook that up, even if the pressure is lower by 100 lbs. Hopefully you guys are still following this and can help me out. I'm out of ideas. So is everyone else that has looked at it. But the answer is out there somewhere.
Have you checked the pressure on the return at the same time as the pressure side ?
I'm going to do that as soon as I get some more pressure gauges. Until it hits max pressure all the controls move freely, so I don't think it is bleeding by the piston seals. Plus it will stall in any position in the stroke. What were you thinking? I'm still looking for someone that has a flow tester.
You may have something happening that is stopping or slowing return causing back pressure and locking cylinders up . Years ago had a Ford back hoe, when you tried to curl bucket it moved about an inch and stopped.What we found was end of rod broke off in side one of the two curl pistons . When we tried to move bucket it would pressure the return side and lockup.
Thanks for the input. I'll be posting what the additional gauges show.
I received some feedback form Jerry at Kin-tec Industries. His company is very highly regarded when it comes to rebuilding the hydraulic pumps on these. He felt that there could be one or more bores of the pump that are worn and this allows the fluid to build to pressure, but not to be able to work properly. He has had others with this same problem and it was helped by a rebuild. Basically, beyond a certain point the pump flows around the worn piston bores. This is the second pump rebuilder that has contacted me to talk about this problem. So before I go through the work of hooking up hydraulics independently, I'm going to remove the pump and send it to Kin-tec to be tested. There wont be any posts until I have that information back. http://kin-tecindustries.com/contact-us/
I am only going to say this once and im pretty sure it is going to fall on deaf ears with a lack of understanding of science to understand what I am saying. If the system is rated to produce 2550 lbs of pressure and you are achieving 2550 lbs of pressure then the pump is putting out max rated pressure. since force is totally a function of pressure multiplied by the square area of the piston and you are producing the max system pressure then the only way that there cannot be movement. Listen carefully THE ONLY WAY THERE CANNOT BE MOVEMENT is if you have an opposing force equal or greater to the force you are using to cause movement. FLOW MEANS NOTHING other than the speed at which you will move a function within its rated pressure range given the fact that the opposing force is not greater than the force you are trying to use for movement!!!!! PERIOD!!!! You absolutely cannot max out the pressure of a function and yet have no movement as a matter of lack of flow. movement will only be created by pressure differential or difference in force vs resistance one of two things is happening here. #1 you ethier have an opposing force equal to or greater to the force you are trying to use such as pressure on the return side of the cylinder causing a massive reduction in the pressure differential thus reducing the force. For example if you have 2550 on the pressure side of the piston and 0 psi on the other you have a 2550psi pressure differential. Ok if you have 2550 on the pressure side of the piston and 2000psi on the return side then you only have a pressure differential of 550psi and in effect only have 550psi of force to work with. or you have a massive resistance created by the possibility of a frozen pin. highly unlikely as loose as all these used john deere machines i have looked at are. #2 And from the many many 710 machines I have looked at that all functioned this way the conclusion that I have come to and have yet to see a 710 prove me wrong is that the 710 is an under engineered pos dog and you are getting max out of the machine and the john deere performance numbers that are advertised is totally a joke and a complete lie and fabrication or just a pipe dream!!!!! Also my brother was an engineer for john deere on thier construction equipment and he tells me that john deeres attitude is that if a machine has so much power it can drag itself into the hole like cat and every other machine i have run will do then that is not good and the machine must be derated. I belive him because all the deeres i have run are just as he described and a cat or case will eat a deere for lunch.
I understand the need to talk down to me like I am an idiot. But I'm not. The problem may be that the speed of the movement is so slow that it is useless. There is some reason why the speed is so slow. I intend to find out what it is. This is possible, but one of the neat parts of a forum is that I have been assured by several owners that the machine is a monster at trenching. The issue most have with it is that the components of the boom are very heavy, and expecting it to be nimble and work quickly is not realistic. It is not an excavator. I have several options on how to continue to figure out what is wrong and until I satisfy myself that it is impossible to make function at a reasonable level for a modest cost, i will keep working on it. When I find the answer I will share it. I have quite few older machines, an Allis Chalmers D45 grader, a 944 Traxcavator, an old W900 Kenworth dump truck, a DD 400 International semi, an ancient White 8 x 10 water truck, and numerous steam powered tractors. I have also restored UH-1 helicopters and radial powered aircraft. All of them were purchase non operating and all of them are used for their intended purpose all the time. The only reason that I went on this forum is because I purchased this as a working machine that I hoped to not need to spend my time fixing it. I am fully capable of fixing pretty much anything I set my mind to. I was hoping someone was going to respond with an answer based on the experience of fixing one, not telling me how NOT fix it. What would be really helpful is if one of YOU experienced guys could come to Southern Oregon and hook up all the appropriate equipment and see the results. With any luck we won't be standing around scratching our heads like the other experienced guys wondering why it isn't responding to the inputs like it should. Until then I'll just keep trying to fix it as best I can.
Seems like you could answer the doubts of several posters by flowing the return of the crowd cylinder into a bucket. Then there is no hydraulic back pressure and the only restriction possibility is mechanical. And speaking of mechanical... Any chance the crowd cylinder has been changed ? Perhaps smaller diameter ?
Its hard to know the skill level of others on a forum. Wasent trying to talk down to anyone but merely emphasise the facts of the science. Sounds like you have aircraft experience like i also do. If you have an a&p like i do then you probably went through school and had some training on the subject of hydraulics. I also hold ase master heavy truck ratings as well as ase master auto ratings. Plus 25 years working on about everything you can imagine. Not trying to impress you or break my arm patting myself on the back. However one thing i have learned in all my training and experience is that it is awfully easy to get your mind locked on a thought that you cannot get rid of and clouds all other options. Most of the time on forums like this you hear lots of opinions and possibilities but no imperical data to back up anything. Such as the case in what you have put forth in testing data and what you have said the machine is doing. I also have my own experience in looking at several of these machines for possible purchase and all of them opertate just as you have described. In fact i even went to an auction in dallas that had 4 of them and they all ran the same with no difference between them and were all in my opinion hydraulically deficiet. When i ran those machines the function would flat stall. They would reach a point where there was no movement at all! And whats most puzzling is when they did this the engine would not load down like on any other machine i have ran. I have a real hard time believing that out of 6-7 machines i had looked at that they all would have the same problem. I could not find one machine that worked as advertised. If this actually is a hydraulic issue and not just a under engineered design flaw then i find it really hard to belive that this is such a common issue that 6-7 machines i looked at all have this issue and no one anywhere has seen this problem or know what causes it. No one anywhere in this huge pool of online knowledge or even dealers and shops could i find anyone thats even remotely knowedgeable about the functioning of this machine. It really is a very baffling thing all the way around and has caused me to steer way clear of this model and honestly anything deere. I really honestly wish you luck and hope you do find it. I would very much like to see one of these operate as advertised. On paper this machine should be a super beast. But yet have to see that is!!!
That's exactly how they are designed to operate. Take a look at the controls, or service manual, or anything written about a closed center hydraulic system, when the function reaches the end of the stroke, or stalls, the engine DOES NOT bog down because the pump is unloaded, the pump cannot tell the difference between a stalled function and a closed valve, same pressure and same flow. I'm glad to answer questions, or clear up confusion as I see it. But I try to follow three and out, suggest something three times with no response, or hear the same nonsense three times and I'm out.
I just came across this but I don't think lifting weights is the best way to test the hydraulics on a backhoe. I think a lot of capacities listed in brochures are based on optimal conditions and hydraulic calculations rather than actually testing on a machine. For instance front end loader capacity could be at the lift pins without the bucket on. Boom lift capacity on a backhoe could be with the stick all the way in which you'd rarely do. Of course if the stick is reached out you'd have way less lift capacity. Someone coming on a forum and bashing a particular machine or brand doesn't help anyone. They came here looking for help in fixing their machine that did run properly at some point not an opinion on the machine they own. Every manufacturer has had some less desirable machines but bad mouthing them doesn't help fix the problem. Not knowing how the hydraulic system on the machine is designed to work and then trying to offer advice on what's wrong doesn't help anyone either. I'm not a mechanic but do know that closed center hydraulics are much more complex than open center. My basic understanding is open center is full flow-no pressure and closed center is full pressure-no flow. Trouble shooting them is totally different other than something simple like a blown hyd. hose.
I thought the tests Jay performed was a good way to verify the pump is not the problem, it lifted close enough to the "specs" that the stick should have decent digging power. Not an accurate way to test, but it didn't cost anything to see if all hydraulic functions were weak! I also agree that bashing or being a smart *** helps no one..
I didn't really think i was bashing the machine. I would very much like to be proven wrong on my assement of this model that i have formed as a result of seriously looking at several of these machines. On paper this thing should be a monster and the size of the machine is very appeling to me for the application i would use it in. I have yet to find even one of them that could even muster up to the power of a case 580 or heck for that matter my old ford 4500. I seriously would love to be proven wrong and actually find and buy one that operates as the monster it should be. If the machine however just does not muster up then how is it bashing it when its just a plain fact?
Something else you might want to think about and very well might be worth the cost of it. https://www.amazon.com/Tractor-Backhoe-HYDRAULICS-Technical-TMS153821/dp/B00SK9WYA2 Then you would have actuall factory information and it should have a troubleshooting guide. Would go a long way to follow the proper troubleshooting procedure and would eliminate a bunch of what ifs and speculation.
Delmar if thats the case then its likely that i have never run a machine with a closed center system and its very possible that the open center and closed center just have a very different feel to the operator in the way that they operate and have very different characteristics. I have got to wonder if jay here is also used to open center system and the way an open center system feels in operation and we are both mistaking what we percieve as a dficency as normal for that machine. I kind of really have to lean this way as i have looked at so many of them that i thought was deficent. I cant tell you how much money i have spent traveling the country to look a several of these machines only to wind up in severe disappointment. To that point when i went to the auction in dallas they also had a 310 deere there that i ran for comparison sake. It to me felt just like the 710 and in my opinion was just as deficient as the 710. Of course my opinion is just as much speculation as anyone else has put forth here. The one thing i am missing is the experience of actually purchasing a machine and getting out the manual and getting all the facts so as to make an informed diagnosis. I am quite certian with a good manual and some time i could figure it out. I just am not willing to take the gamble to buy a machine and then find out in the end that it just is not designed to perform the way i think it should. I have already spent enough money to get experience i have with these machines. Sometimes you just have to ask yourself. Your foots already in the trap so just how much more cheese do you want lol?
This is all you should have posted in the first place not understanding that a JD has a totally different hydraulic system than a Case or a Ford. This isn't bashing? "and have yet to see a 710 prove me wrong is that the 710 is an under engineered pos dog and you are getting max out of the machine and the john deere performance numbers that are advertised is totally a joke and a complete lie and fabrication or just a pipe dream!!!!! "
Well i would recomend that no matter what type of system it has. I pretty well all along thought i kind of stated that you need all the diagnostics information like pressure tests and where. The manual will give you a clearer picture of where to get that data and what to do with it once you have it. Dosent matter what type of system you have every manufacturer is gona make it a bit diferent and they all will have their own little idiosyncrasies.
I think you would be better off reading some service manuals and understanding how a specific machine operates instead of offering advice (ad nauseam) on a machine you're NOT familiar with.
Well since i have spent considerable amount of money to get first hand information and compare as many machines as i possibly could and have formed this opinion based on the fact that i have yet to find a ma hine that will prove me wrong then no i dont consider it bashing. I have spent much money and find it quite factual and i now give you this information for free at a great cost to me. I pretty well think i have earned my thoughts
Ok what advice have i given ad nauseum other than gater data and get the facts? I have gone into some basic hydralic theory but thats not advice on a fix. In what maintenance manual have you ever seen a diagnostics procedure to lift concrete blocks and make an i think so estimation?
Really i find this statement pretty funny. Im not familiar with them? I took the intelligent aproach to the possible purchase of this model and i became familiar enough with then to know to keep my money safely in my bank account and not find myself in the position Jay here now finds himself. Yea guess that makes me the dummy. Really i think Delmar is the smartest on here and im gona follow his example!!! Out!!
That manual is a bargain at $40. It sounds like Jay has sent his pump off to be rebuilt, so if they are half as competent as their website seems, then he should get it back good as new. It will be interesting to see the results. The controls are all in the pump as far as I know. Maybe we'll get a back pressure reading if it doesn't have expected power? Workshoprat is the only one here besides Jay who has ran a 710 so your advice is as good as any, if you tried several of them then that's more than Jay or I. This is a safe space and your feelings are just as valid as anyone else's Lantraxco, Mobiletech and maybe a couple others had way more experience with these JD's. Too bad I scared Lantraxco off with that roundup thread, didn't mean to, sorry? I thought most modern excavators used closed center systems. I don't have that experience to know how they feel compared to the JD system. I know that my 610 has enough power to bury the bucket in nearly anything and stall, and once it stalls the stick the boom is stalled too usually so you're sitting there with both levers back and the engine with no load and nothing happening... A little time with it and you can keep the pump operating in the middle of the curve, taking reasonable bites and keeping the bucket moving.
Ok i know i said out but i have a very hard time keeping my mouth shut lol. As far as the difference of operation from this machine to others something we also have to keep in mind is the machine weight. This machine is considerably heavier than say a 580 or my old ford. My old ford is so light its about impossible to stall the crowd because it will drag the machine into the hole instead. This may give the perception of extremely powerful when really its compartivly no better than a 710 for its given size just that a 710 and its weight you can hook to the ground where you can utilize its full power and actually cause funtion to stall. I could see where this could cause a perception issue.
Just curious Workshoprat, did you buy or do you have the the John Deere technical manual that you posted a link to ???
Jay; would you consider posting some photos of those tractors in the Agricultural Forum ? Sorry to go off topic !
I just posted a link to it trying to be helpfull. I consider a manual a must for working on something this complex.
Ok, I'll try to gather up some. It is a marvel to me that any of them work, but yet they do. That is why having a new one that doesn't is such a puzzle to me.
Nice of you to post that link workshoprat, but I am wondering why you spent so much time and money looking at those machines and never purchased the technical manual. Perhaps there is information in it that would enable you to figure out what the problem is with those 710's.
I just did not see the need to persue it any farther and figured i was money ahead to just stay away from what appears to be a very problamatic machine.
Jay E how did you make out with the 710?
Here it is a couple of weeks later and I've spend several thousand and 40+ hours and I've got... NOTHING. Well that is not quite true. I have a first class education on how a closed center, radial pump destroke enabled, 2550 PSI standby pressure, john deere hydraulic system operates. I now own a $2000.00 flow tester, 6 500 PSI gauges, $300.0 worth of diagnostic tees, dozens of plugs and caps, a spagetti pallet full of hoses, $250.00 worth of new hydraulic oil, and every applicable John Deere manual I could buy and read. I did not need to buy and install a $6000.00, 3000 series pump. I did not need to buy and install a $3000.00 complete control valve assembly. I did not need to buy and cylinders. So I guess I'm ahead. Both of them work perfectly, in fact the pump worked above spec. As near as I can tell, these machines are just under performers. Could John Deere have inflated the specs to make a sale ? Naaah, they wouldn't do that. Funny thing though. The 710 G has a pump that puts out 5000 PSI of pressure, about double what mine does. Yet it only has 30% more lifting power. Double the hydraulic pressure should result in double the force. The fact that it doesn't tells me that the 710D was never able to do what the chart says on 2550 PSI. So mine has 40% less lifting power than the chart, which is amazingly close to what it should have if doubling the pressure gives you what the G model has. The machine is SO HEAVY. It is clumsy to use and is not agile. Because it is heavy, it masks the power it has, so even though it may be digging as well as a 410 (which I havent put it directly against yet) it feels slow and doggy and underpowered. If I could put on 410 sized buckets it would help a lot because the geometry would be much better. I may figure out how to do that, it could just be a matter of machining undersized pin bushings. Final word. I'm going to turn up the pump to 2800 PSI. 300 more should help the power, but makes operating it very abrupt as its designed to move at 2550. It will be bypassing in swing and boom down, but that is just too bad. If I could I would crank it all the way to 3000, but then it would heat up and wear out quickly as every thing will be bypassing. Thank you to everyone who responded, a lot of your input was right on the money. If I can find a nice 410G I'm going to send this one down the road. Good luck if you own one.
Good grief Jay ! That is one of the saddest things about any T/L/B I have ever read. Not only the lost money and time, but to go through all that and end up with a piece of near useless S***. It has to extremely frustrating.
dam, that is so disheartening. I'd never look at a 710 again!
Saga continues. Today I went to work it and the engine was down on power. It simply would not govern itself into a stable RPM. Started with the fuel delivery ( filter, hoses, seals) and went all the way through the diagnosis. Valves were so far out it appeared they had never been adjusted since new. In the end the only thing left is the pump, finally took the injector pump out to have it rebuilt.
The last and final post. The new pump was installed and what a difference it made. Ity turns out that these six cylinder engines are pretty highly stressed and if the engine is not working PERFECTLY, the power to the hydraulics is uneven and they work like ****. So along with everything else that I did, I finally have a machine that is smooth and powerful. It still wont lift to spec, but it is good enough for me. BUT WAIT.., After 20 gallons I've developed a popping through the exhaust and now everything is running like crap again. Bottom line, fix everything hydraulic and mike sure the engine purrs. If not, find my next thread, hopefully we can fix the miss.
My 410 might be completely different. The pump builds pressure against closed valves. When it reaches a specified pressure, the pressurized crankcase of the rotary pump overcomes the springs, and pistons don't return toward center. A closed center machine varries pump volume to maintain high pressure to each valve. As the moving of oil is what consumes horsepower, these systems are very efficient, and they start easily, as a few revolutions of the engine builds this pressure, then pump pistons stop moving. Mine leaked through the spools in three of the backhoe valve sections making it function like an open center system. In my case this rendered the pump unable to satisfy the steering priority valve. Net result was no pressure at the cylinder. If you have pressure at the crowd cylinder, but no movement, I believe you have a bad cylinder seal on the piston. An infra red camera will confirm. Start the engine cold. as oil warms, check what parts get warm. If the crowd cylinder isn't moving when you try, either oil is flowing where it shouldn't, or the piston is stuck. I'd guess oil is flowing around the piston inside the crowd cylinder. The pump is unable to keep up with the leakage to the reservoir.