after reading the post by ala millwright last night,it really got my curiosity up,because my 82 310a has the same symptons.i have always felt that one day i may have to split the backhoe to figure out what the problem is,but it seems like quite a large project.i was hoping that while reading the text in the old post,that someone might have figured it out,but obviously not.when i start it up cold,it will run about 30 seconds before you have any loader function at all,doesnt need a destroke valve because it starts right up.when the backhoe is operated for about 45 minutes and get fairly hot the loader function becomes very slow,even with increased rpm.the standby pressure is set at 2300 psi when the oil gets a little warm,when i operate a function the pressure drops to about 1200lbs.you can always hear a little bit of chattering in the steel lines going to the main pump,and when checking pressure,the gauge does fluctuate quite a bit.also when i first crank her up,it will go in to reverse immediately,but it has to run about 10 minutes to engage in forward,once it makes the initial engagement,it,s good to go.i can move in to a dirt pile even in low gear,and the clutches will not slip,the motor just bogs.one other issue i have,is when warm,every function drifts terribly,i can put on pallet forks,and watch it drop in about 15 seconds.i have had the loader valve rebuilt,and all front cylinders rebuilt,what do you guys thinks? also one more thing,when i operate the backhoe,the front wheels will turn themselves slowly.thanks for looking ,steve
How about backhoe function when you first start it up? The loader valve is "shut off" below a certain pressure by the priority valve so if your steering valve is funny then that could cause issues for the loader but the backhoe would see the full system pressure. The pressure dropping to 1,200psi is normal, the pump TRIES to maintain the standby pressure, but it can only supply it's max volume and the load on the function determines the PSI at that point. Have you changed the fluid, checked the screen, and taken apart the old filter? The chattering in the line sounds like cavitation/air from the charge pump, so a plugged screen or other problem with the charge pressure is the most likely cause. The technical manual would have all the procedures for checking valve leakage and charge pump pressure/flow, but you can figure this out without the manual and a flowmeter if you have to. Re read what Willie(ATCO) said in the other thread, leakage makes HEAT, you can start it up on a cold day, let it idle and see what components get warm first. Then figure out what it does in the system and if it should be leaking or not. The priority valve is essentially a manifold that supplies the other valves, so follow all of the hoses off of there to their destinations, or just feel if one is much warmer than the others and follow that one. With a closed system, any of the hoses to the valves (brakes, steering, loader, backhoe) can be capped and then run it like that to see if the symptoms change. Nothing in this system is hard to pull apart and inspect, but you want to have a pretty good idea of what it is before tearing into anything like this. I don't have any experience with those symptoms, but I have a rough idea of how these Deere systems work. Edit: I'm assuming the hydraulic pump is supplied with pressurized oil from the transmission/reverser, but I'm not positive that's where it comes from. A manual sure would be helpful.
i have changed both filters,disassembled and checked the priority valve,and pulled the screen and checked it,it was perfectly clean with no debri.i,ve also checked the check valve underneath the hydraulic filter when i was in there.the backhoe seems to have almost immediate function.i ran it for about 30 minutes one day and checked for hot spots with a lazer gun,but could not find any.the only thing i couldnt do was get to the base of the steering orbital valve to check for heat.the function drift really has me stumped.unless its age.
The drifting doesn't make sense to me, unless it's spraying oil all over the ground then either the valve or cylinders are faulty. Doesn't matter if the hoe is off or on, the cylinders shouldn't drift like that. The steering turning slowly when you use the backhoe is kind of odd. The steering (and brakes) TYPICALLY dump back to the reservoir, not back to the charge circuit for the main hydraulic pump. That MIGHT make the steering valve a suspect for leaking? When you say you ran it for 30 minutes and checked for hot spots, was that letting it idle without moving anything? and nothing got much warmer?
So the charge pressure off of the pump falls off as the outlet pressure falls off?
yes ,that was idling without moving any functions,and if i remember correctly,the charge pressure does fall slowly as the oil gets warmer. the drifting really has me puzzled ,because every function on this machine will drift badly.when it is run for a short time everything has great power,but even when i,m using the backhoe ,the stabilizers will even drift down.and there is no leakage at all. thanks for your response.
OK, what is the pump inlet charge pressure with the engine at FULL speed and one of the functions FULLY stroked?
i will check that this weekend and let you know,thanks
While you're at it, get the pressures first started up, when it's starting to lose power, and when it's much worse. Full speed, one valve fully open. And full speed no valves open. Six readings total, that should be a good start.
You need to isolate the systems by capping and plugging lines, steering, brakes, loader, backhoe, all can be leaking off. Drifting with controls in neutral has nothing to do with the pump, I don't care what's been rebuilt, if your cylinders are drifting you have bad seals, worn valve spools, or possibly check valves in the spools or valve sections leaking by. Charge pressure is key to keeping the flow going, but half of the charge flow to the main pump comes from return flow, the valves in the the filter head direct the flow and keep the pressure up. In other words, the charge pump in perfect condition at max engine rpm will only supply half of the rated flow to the main pump. Everything has to be working properly for the system to perform well, it's an orchestra not a pump solo, lol. Cheers, Lanway
well, it has been raining here so much that i can,t get the backhoe out to work it real hard,but i did warm her up real good and checked my charge pressure a few different ways,probably not exactly the way you all wanted,but here,s what i got. when i first started her up idling at 800 rpm she took about 20 to 30 seconds to register,then creeped up to 25 psi. when she got good and warm after about 30 minutes i brought the rpm up to 2300,the pressure went to 50 psi,when i raised the loader up she dropped to 15,but when i dropped the loader down she went to 95,curl function up 90, curl down 20,stabilizer up and dead head 60,activate steering at 2300,she,s steady at 45.when i dead head the loader curl function either direction she stays at 70.when i was done with these tests,she has about 10 psi at 800 rpm.probable not the exact tests you need, but maybe this will help,thanks for looking Steve
That's helpful, when you cycle the cylinders to retract them, you get more oil returning than the pump is putting out, so the charge pressure goes up to 90 psi which is probably where the relief opens to let the excess flow off. So, the recycle part of the hyd circuit would seem to be working okay. Your charge pressure is way low, so you either have a bypass or leak off somewhere or it's a valving issue. If I remember correctly the charge pump also works the reverser? If that's working you have to have more pressure than that at the pump, it's either leaking off or a valve malfunction is not allowing enough flow to the hyd pump. My guess.
The manual for the 310 pump says the minimum charge flow should be 12gpm at 150 psi at 2500 rpm. This is for the older 310 not the 310A, so not sure if they use the same pump.
thanks for looking guys,i geuss i will start blocking off a few things one at a time to see if i can find the problem,if not i geuss i will be back to looking at the charge pump,which means a split,thanks again,Steve
I agree with everything chroniekon and lantraxco said, except you said that it takes 10 minutes to go into forward. That's not right, neither is 30 seconds to get any hydraulic function, unless it's below 0. The charge pressures should be close to the 12 gpm at 150psi (the return makes up the rest) so all the things lantraxco mentioned as affecting the charge flow are still under suspicion. The way the pressure drops way off at idle seems like it's struggling. The charge pump is a gear pump that should put out a constant flow (/rpm) that is regulated by various "relief" valves, it looks like your pump isn't meeting the demand (weak pump, or leaks) so the valves aren't operating except when retracting a large cylinder. Apparently JD and Case used the same reversers/shuttles, so you can read some of the Case threads to find out the common problems with them. You can check the charge pump flow/pressure without splitting the tractor. It would be worth getting the manual before you go to the trouble of splitting it, or even doing more than changing the filters/screens in my opinion. You are SURE you checked the transmission screen and filters right.
310a revisited yes that was one of the first things that i did,because it seemed that the oil supply was the culprit,it was almost perfectly clean,i was amazed for an older machine.i forgot to mention that when i put a gauge on the reverser it will jump to 120 psi in reverse almost immediatley,but when i shift to forward,crawl under the machine with a friend in the seat,and watch the gauge,it will show zero pressure,for about 10 minutes,then jump to 120 and your good to go.
Looking back over the thread and catching up, the JD and Case from the C up through mid K series use the same BW shuttle but it is a stand alone unit not using any tractor flows and pressures. It has its own reservoir and pump and cooling . Prior models up to the C used the internal shuttle contained within the tranny casting and had to be split to access. The BW was used in the modular built units. Mel
I would guess a bad seal ring in the forward clutch pack or in that circuit. If you have 120 psi at the reverser I would think the pump may be okay, may be internal valve or leakage issues inside the reverser. As Delmer indicated you need 12 GPM coming out of the reverser, might be time to find the service procedures for the reverser, see if there's any adjustment on pressures, and then get a flow meter in right where the oil exits the reverser unit?
So is that the JD, or Case, or both C-K shuttles? I think I understand that the modular/Borg Warner was independent of the hydraulics and used in the 310C which went to a gear pump instead of this radial piston pump system? And the Cases were all gear pumps? Also, a DIFFERENT JD manual shows an adapter that goes in place of the filter head to test pressure/flow, but you really need a manual, or somebody like Melben who speaks Deere.
Case always used gear hydraulic pumps till fairly recently, IIRC the Ms were the first to have axial flow piston pumps for main hydraulics. I can think of no situations where Case used the transmission oil supplied from the transmission to operate the main hydraulic systems, they were always separate systems.
i do have the manual on file,but finding somebody local that has the proper flowmeter may be a challenge.the manual does show the test fixture and has the specs,i geuss i will put out a few feelers and see what i come up with,i really do appreciate everyones input,thanks a bunch,Steve
The steering valve has a check valve in it were flow comes in or out you can notice it I bet ball in there is messed up or spring I bet that’s your problem with steering drifting and as for foward going in slow I bet reverser broke a spring in side also in the tech Manuel it tells you how to fix and shim to not get late shifts and on the pump in front there is a filter screen on the bottom but on the head of pump check that cause rubber finds it’s way