I've got a John Deere 410 backhoe with an hydraulic problem I am trying to troubleshoot. The Hydraulic pump seems much newer than the machine. The manual says it should be 1800psi on the pump output. I put a gauge on it and started the machine in idle (800rpm +-) and the pump output showed 1800psi at start but then a few seconds later drops to about 800psi. Any ideas what can be causing the pump output to drop like this? Nothing done on my end just started the machine and it starts at what it supposed to and then a few seconds it drops. Thanks, Tom
A technical manual will save you a lot of guessing. Your gauge is hooked up to a small test port, right? If that's a radial piston pump you can plug/cap the outlet of that pump and try it again. If it does the same thing then the problem's inside the pump or pump control valve, if the pressure stays high then you know to look downstream.
The pump might be bad, the link to the engine might be bad, but likely there is oil flowing somewhere it shouldn't. Mine was fine for 15 minutes, then no power at all. My pump looked to be a remanufactured one, someone suggested I get a IR camera, and start cold, see where it gets warm first. Those closed center systems have an 8 cylinder radial pump. Pistons are pushed toward the center crankcase by springs. A cam pushes one at a time out building pressure. That pressurized oil is piped to the pump crankcase. When pressure is too great there, the springs can't push the pistons in. They are said to be out of stroke. When the rest of the machine is at rest, pressure builds against the control valves throughout the tractor, then the work of pumping, and moving oil ends. If a valve is leaking past, oil is being pumped wastefully, and pressure falls. Mine proved to be three sections in the backhoe control valve. The hydraulic rebuilder said he didn't believe they were worn, probably bored too big for the spools when built. A new valve would have cost as much as the tractor was worth. I opted for a component valve to replace. This meant new mounting bracket, joystick linkage & bracket, and hose challenges. All had to be fabricated as a one off. Willie
Delmer: I hooked it up where the manual called it as the outlet test port on the pump. I'll plug the outlet port on the pump and try it again. Before I got to this point I changed both filters and cleaned the screen. The screen was pretty bad and hoped that was going to resolve it so I put that all back together and the loader and backhoe are barely moving at all (the original problem). This lead me to the pump pressure test. Thanks, Tom
Check the two valves in the hydraulic filter head, one is the bypass so no big deal, the other is the charge pressure regulator for the oil coming from the transmission to supercharge the hydraulic pump. If it's stuck open or has some debris stuck in it, you lose the charge oil back to the tranny tank. No charge pressure, no pumpage. I believe the charge relief has an O-ring on it which may have rotted away also?
Some of the Deeres have a test port on the hydraulic pump to measure the charge pressure coming from the transmission. If not you can get the fittings to make it work. It's in the couple hundred psi range.
Ok, I plugged the output from the pump and got 1200-1300psi at 1000rpm. The manual says for my serial number I should be getting 1700-1800psi at 1000rpm. right after my model (another 10,000 tractors made) the spec changed to 1300psi. The pump I have is an Army provided replacement (green) JD pump. I looked on the pump and found this data: * ROPVJD1045827 RP1065EOE0600 I'm not sure how these come from the factory as far as pre-set psi but this is an Army 410 machine and wondered if I can and should raise the pump's PSI output? The machine has always been slow (loader and Hoe) but only recently after a few hours of heavy work became too slow and the backhoe hardly working at all....I expect something happened. The screen was clogged so I cleaned it and was hoping that was the problem but now know I have another problem since it worked ok before and not now. From what I can tell from the manual the transmission has its own pump and the machine is driving fine so I thought the front pump only worked the loader, backhoe, brakes and steering. Lantraxco: I took the hydraulic filter housing head off the machine when I cleaned the screen and it appears to be as per the manual. I also changed both filters when I cleaned the screen. Thanks, Tom
Okay, there's also a very fine metal screen in the stroke control valve on the pump, have you removed and cleaned that yet? I do recall the old 510 we had one place I worked if that screen plugged the pump would destroke.
I was hunting through the manual for that filter/screen. Where there is usually a stroke control valve mine doesn't have wires or the T manual stroke. I have a smaller bolt within the larger bolt (if that makes sense). I assume the screen is in that port and I remove the larger diameter bolt? I've been afraid to remove any of those bolts from the pump expecting a spring loaded jack-in-the-box.
I see some versions don't have the screen, if yours has it, it should be under a blank cap plug right next to the adjustment screw which is I think your smaller bolt in a bigger bolt, that's what it looks like. #15
Well, unfortunately no filter in the pump. I ended up taking the housing off to understand what was in that port since my pump appears to be different than the 3 diagrams I have....including your's above for that port. That filter port seems to have various optional designs so I put it back and still 1300psi at 1000rpm on the pump. I still have the pump output side capped and was hoping to figure out the pump problem before going downstream. Even when I raise the rpm to 1300 the psi stays at the same 1300psi or lowers a bit. Is there a way to raise the output psi at the pump? When I first turn on the machine it jumps to 2000psi and then gradually (30-45 seconds) drops down to the 1300. The manual says the pump should provide between 1700-1800psi for a 410 with my serial number. The exact wording is as follows in the manual: Control Valve Pressure Setting ( - 246127)............................1700-1800 psi at 1250 rpm Control Valve Pressure Setting (246128 - ).............................1300 +- 50 psi at 1000 rpm My serial number is 235836 By the way my destroke port is the 35B, 38B, 39B shown in your above diagram. the top side is a smaller bolt in a larger bolt cap. Thanks, Tom
Well, if there's a regulator spring 38B in there, that's the pressure setting, the bolt on top is the destroke? Must look like this:
Yep, that is what I have. That is the set-up of the other port I was hoping to find the filter in too. I did notice on the bottom of the destroke port the threaded end has an allen key end (part 32) so expect if I loosen the nut (part 31) then I can screw it in or out to adjust psi? Do I have that right? My guess would be to screw "in" part 32 will increase psi? (50/50 chance).
That should be correct, shortening the spring should make pressure go up...
I appreciate the help lantraxco.
The pressure dropping from 1,800 initially to 800 or whatever in a few seconds is suspicious to me, but I have no experience so it could be normal? I'd still be looking over all those little control valve parts for anything suspicious, and maybe even sucking the oil out of the pump to see if there's anything floating around that could be jamming the spool and not passing.
:iagree
Are you certain you don't have flow by to the reservoir? Unlike open center systems, these depend on NO flow to the tank to build pressure. Like a household plumbing system where no water flows until you open a valve, pressure drops when flow is great. Somebody is in the shower, flush a toilet, they get scalded. Cold pressure drops. The one I had years ago I capped the hose supplying the backhoe valve, and everything else worked fine. Replace backhoe valve, symptom went away. Willie
Yea, I figured I'd try to tackle the pump first like you said in an earlier post and then will see what happens when I uncap and let it flow downstream. The 1800 to 800 drop was before I capped the pump outlet also the 1800 was that initial start up psi. I don't expect I have or will resolve the issues yet but am trying to eliminate stuff. With regards to flow to the reservoir I figured I'd go there when I know the pump is producing the correct psi and there is no junk floating in it to jamb up the spools. When I first lost the loader/backhoe control (serious slowing) I did remove and clean the lower screen which was 90% clogged and also changed the other filters. After that I figured I'd be good but still very little power in the loader and almost none in the backhoe.
Another question: what was the stuff clogging the screen? black fibers or metal swarf?
Looked like black fiber and soft rubber bits. A few years ago I had taken the cover off the hydraulic tank and used red form a gasket when I reinstalled it...a few pieces of that red gasket material were in the screen too. I have changed about 4-5 hoses and removed 2 obsolete hoses to a 4-in-1 (clamshell) backhoe bucket attachment no longer used. When I opened the pump port in hopes of finding a filter the other day there was a lot of fine black dirt in the crevices. When I removed the pump output line it did drain out all the fluid in the pump. Is their a better way to flush out the pump?
That's better than metal pieces. I was thinking the control valve spool in the hydraulic pump could look fine, but be plugged up quickly by a piece of junk that falls back into the pump when you open it up. Don't know how you'd get it out though. A charge pressure test is a logical next step. Just like you don't want to mess around with the backhoe valve when the pump isn't putting out pressure on it's own, you don't want to mess around with the pump too much until you know it's getting enough pressure in the oil supply it needs.
There is a screen/filter located behind a pipe fitting in the frontal lower right part of the transmission. Is that not the pickup screen responsible for supplying hydraulic oil to the pump?
Yes, the transmission pump gets it's oil there, and supplies charge pressure to the hydraulic pump. The hydraulic pump she no suck.
I am going to raise the pressure to at least the low end of the 1700-1800psi and then hook the pump outlet line back to feed the pressure control valve and see what happens. My guess is that between the screen size and the regular filters that a very fine dirt can still get through to the pump. My manual shows a set-up to install a 10 micron filter temporarily within the system to clean it up but not sure if it can extract dirt from the pump. Would my hydraulics (loader and backhoe) operate at 1300psi? Just curious because the previous owner (Army) may have set the pump at 1300psi since this tractor changed from 1700-1800psi to 1300 in a later serial number. The pump is a replacement and could have been mistakenly set at the newer setting when installed. I do list the pump serial number and model number in this post but couldn't find a way to tell what year it was manufactured. I assume the serial number has a digit that states the manufacture date?
Yes, they'd operate at better than half the force with 1,300 psi. All bets are off with something this old that you already know has been messed with. Serial number might as well come off your box of cereal, unless it has unbroken factory paint.
I would check the charge pressure first myself. If you do turn the adjustment screw on the pump, count the turns as you adjust, if you find the pressure is not rising that way you can back it out to the current setting. I like to make a mark with a silver pencil or soapstone, but then I can't remember my own name sometimes. I've seen gear pump systems where the pump was worn so bad the owner had the main relief valve screwed down tight. You can imagine what happens after a new pump is installed the first time a cylinder hits the end of stroke. Sometimes it's a hose or fitting, once I saw a brand new cast iron pump housing shatter, good thing nobody was standing near. I think you're misreading your manual, no offense, that pressure didn't seem right to me so I checked the specs, that pump should go 2,350 psi deadhead, the pressure control valve which mounts on the side of the transmission case is set for the lower pressure for I believe oil going to the loader valve? The steering and backhoe I believe run at full pressure. The valve on the pump is the stroke control valve, not pressure control. Love Deere. https://www.deere.com/en_US/docs/construction/non_current_products/backhoes/410.pdf
Yes, definitely will keep track of turns and put it back if there is no change in pressure with the adjustment. If the length of thread has any meaning on the pump adjustment it appears to have lots of room to go either way. I am going to be very careful and just see first if that pressure adjustment works and then uncap pump output and hook it back up downstream to check the pressure control valve. I've got the rear wheel off and blocked up still so have great access. I think the pump has all unbroken paint and it looks brand new with even pieces of white paper under many of the port bolts....not sure why they are there but looks like maybe the way it came from the factory or rebuild shop (wishful thinking maybe). Again the pump is JD green so expect the original was construction yellow.
I adjusted the pressure and although not much happened the first turn the pressure went up to about 2250psi in the next half turn and is holding steady at about 1000rpm. Can't explain it but it is staying there so I removed the cap and hooked up the line downstream. The loader worked better than ever but nothing from the backhoe. Of course had a bunch of fitting leak assuming to the added pressure or I hadn't tightened them enough. When the problem started before I messed with the pump I had removed the pressure relief valve, filters and filter head and the screen. Only the spring came out of the left side of the valve and the rest didn't come out but the valve itself was sliding within the housing. Not sure if that is right but it seemed odd and I couldn't remove anything but the spring and a couple small washers. With no backhoe I'm assuming there is an issue with this valve since it opens the line to the backhoe? The picture is what I have. Is there something to look for since I expect I'll have to take this area apart again?
That would be the pressure control valve, yup. Not sure of the exact functioning anymore, but it has pressure in from the pump, pressure out to the loader and the backhoe separately, and a return to sump through the mounting to the tranny case. I believe it regulates pressure to the loader functions which I guess would make it a sort of pressure reducing valve? You shim the spring to set the pressure to the loader valve.
I think it is a steering priority valve. The backhoe would not be in use when steering is needed. The loader might use up needed pressure, so it blocks most of the flow to the loader when pressure drops. Mine steered OK, but it took five minutes to raise the loader to full height. I forget the volume of these pumps. If flow exceeds the volume pressure drops. These systems were very complex for the day. Sadly few factory trained mechanics are around any more to fully understand them. Willie
Steering tees off before this valve I think.....
Yes, the steering tees off before the pressure relief valve and works with that gas charged cylinder. My steering has been great so this pressure relief valve comes off again and I need to see why it isn't directing flow to the backhoe.....never a dull moment...but the loader is much better than before so expect my pump pressure was low since I got the machine. I also think the pump had a piece of dirt in there and must have been blown out.
Yeah, it just restricts flow to the loader when pressure falls to give everything to the steering. They didn't include backhoe 'cause you don't use it when steering. Willie
I wanted to thank everyone for the help with my 410 and follow-up for those troubleshooting their own problems: It looks like I had 3 conditions and the problem appears resolved: 1) The lower screen was pretty well plugged so I removed and cleaned 2) The washer between the spring and orifice in the pressure relief valve was worn flat and stuck in the housing (replaced the spring, orifice, all washers and O-rings) 3) The pump wasn't holding consistent pressure (adjust the pump as specified in this thread and set PSI to 2100) Changed a couple hoses that were damaged, changed both hydraulic filters and all fluid. Not sure which was the most critical but everything works well and will run it all day tomorrow with fingers crossed. Appreciate the help, Tom
This was some good reading, I have a john deere 310a owned it for 20 years now and it always had a vibration in the pump or more so the large steel pipes that are on the right side of the machine. Now when I pull any lever loader or the hoe the vibration go's away for as long that function is moving. Everything works fine just have that vibration when nothing is working [hoe-loader] I have cleaned the screen by the two filters as well as changed the two filters over the years. I think there is a screen in the pump but don't know were it is???
Flyingpassage, you're not going to get a better answer than lantraxco's in your other thread.