I've posted on this machine twice now. My issues with it have gotten worse and I'm not getting any where with it, it now has dead hydraulics and is sitting in the middle of the driveway were I moved it to work on it. Not a big deal to me cuz I think it's a good looking machine but my wife is a WHOLE nother story! This is what I've done, I've checked the pickup screen, changed filters and hyd. Fluid. I've checked pressures at the hydraulic pump, my main pressure was low slightly and my charge pressure was fine until I moved any function then it drops to zero, since the problem has gotten to where the hydraulics are dead, my charge pressure stays at zero. I disconnected the feed line to the main pump ran it into a bucket and got aprox. 4 gallons in 20 seconds of running the engine. I have removed a piston in the main pump at it looked it really good condition. I've checked the transmission filter relief valve and it seemed okay but I'm not sure exactly what to look for. On top of it all the machine slips in high range, pulls ok in low range. I figured the problem could be connected. Sorry for all the info at once, I'm not sure what to check next, my guess was pressure regulating valve but can't find where it's located. I'd really appreciate any help.
Dead main hydraulics could be a sticking stroke control valve in the main pump. It controls stroke in pressure and if it hangs then you have no flow or pressure.
Can I check the stroke control valve by removing the plug on top of the hydraulic pump, that's above the solenoid? Thanks for the reply
The stroke control valve is reference #'s 26 to 32. It is a real pain to remove and mainly reinstall in place even in the larger tractors (4440). The destroke solenoid or as my 310 has a T screw, is directly above it. The valve is held in place with a 1 1/8" plug with adjustment screw in it which I don't think the front casting will allow access to.
Sounds like removing the pump would be the way to go? Do you think this would cause no charge pressure as well as no main hydraulic pressure?
I'm not sure if it's significant or not but, I unplugged the destroke solenoid valve today started the machine and I was able to raise the loader and the boom. The hydraulics definitely are not working(it was just different than zero response) I also noticed while grabbing lines to see whats hot or cold, I felt like a hammering or heavy vibration in the hydraulic pump output line. Figured its worth mentioning.
If it will raise the boom, it is building close to normal pressure. The hammering is the eight pistons being pushed outward by the rotating cam and could be some shaft bearing or cam ring and needle bearing issues there. If you have flow from the charge pump, you may have some internal failure in the main allowing through flow. Rebuild takes some special tooling, but disassembly and inspection isn't difficult. May find some exhaust valves leaking or failed. System is the same as the farm tractor it is built upon (likely a 2000 series 2550, 2750 etc.).
The pump is coming off then! hopefully by the weekend, I'll post some pics. Thank you for the assistance
pump removed The pump is off, i took some pics of some of the internals. This pump seems to be in really good shape! Not sure what other parts of the pump to look at?
The sleeve in the bottom pic is the stroke control valve. I've had them stick and kill pressure which is adjustable by the screw in the center of the plug under its spring. The front cast plate holds the front bearing in place. Behind the bearing is the cam and bearing ring which contacts the pistons. I noticed in an earlier post that unplugging the destroke solenoid allowed it to work some. Maybe it is partially holding the stroke valve off its seat?
Everything slides in and out of the bores by hand fairly easy. I'm going to put 12v to the solenoid and see if it's working. I'm beginning to wonder if someone replaced the hydraulic pump not long ago. I can turn the main shaft by hand easily, not sure if that should be? I don't want to reinstall it till I'm sure it's not my issue. Would you pull all the pistons?
DON'T do that without a manual, the coil is NOT 12V and will burn out in seconds, at least the newer ones? The shaft turning "easily by hand" doesn't seem right to me from memory. It seemed like the spring pressure was too much for me to turn it. What does WRWTexan say? With one piston out, you should see/feel the cam/eccentric movement if you turn the shaft a full turn.
Thankfully I read this before the 12v test! Don't need anymore problems lol I'm thinking about removing all pistons just because I'm this far, I may as well be sure it's not the pump before I reinstall it. I called Deere today and asked if they could bench test the pump, I got a no on that one. The tech told me they are only tested/turned on the machine itself. It does turn pretty easy. Something interesting to note, I removed the radiator to access the bolts to remove the pump, I needed a bucket to catch the fluid and the only one free was the one used to test the trans pump flow, and still had some fluid in it so I dumped it, at the bottom of that bucket was like a blue gray silt that settled out of my hydraulic fluid. My filters and fluid are maybe 5-10 hours old. I'm not sure if this red flags my brakes or related or non related to my dead hydraulics issue?
With one piston out, you should see/feel the cam/eccentric movement if you turn the shaft a full turn. Can you feel the crankshaft oscilate when you turn it? It will move about an inch.
The pistons are backed by a spring but may tend to cancel each other out when turning. As Delmer said, you might pull one and see if you notice a spot of resistance. I believe the solenoid is 12 volt as it is a standard coil similar to what is found on most safety lockout valves, and there would have to be a calibrated resistor in the system to knock it down from 12 to 6 and I don't know of one on them. Items 10-12 and 17-20 are the intake and exhaust valves respectively, which the exhaust side can fail to seal as the other pistons pump, allowing backflow. The blue grey silt may or may not be related to your problem but it sounds like what I have a 4840 powershift clutch pack out for. A brake piston had pushed out and hung and the brake plate was ground up and spread throughout the system like aluminum paint. One clutch piston cavity was packed full of metal powder and wouldn't allow the piston to return upon de-application. Swipe a magnet through it and see if anything sticks.
I'm just going by memory, but it SEEMS like I couldn't turn the crankshaft on the pump by hand, not easily at least, that's with the springs and pistons installed. You wouldn't be the first to break that shaft, not that it's common, but anything can happen...
The shaft definitely turns the crank, it has resistance till I hit the spot with the piston removed. The exhaust valve seems to have a lite spring but, is clean and in good shape. To access the 17-20 parts I would need to remove the rear block of the pump that's held on by 4 bolts?
I took a pic of the chewed on shaft, I'm not sure what that's about, doesn't look as though it slipped in the splines.
You definitely need a new shaft and the coupling it goes into. It is not unusual to see that kind of wear on a high hour pump.
That missing spline isn't causing your problems at the moment. Yes, the exhaust valves come out the back. The picture is the intake valve, I think. WRWTexan said the exhaust valves can leak allowing backflow, but to completely disable the pump the exhaust valve, and intake or piston on the same cylinder would have to leak significantly. Put the pump back together and see if compressed air will blow through it backwards, that might tell you something? Then clean the outside before you take it apart anymore.
Splines are fine. Delmer, I agree about the exhaust valves. I was thinking they could be causing the low pressure problem. I've seen them with a deep ring worn in the valve plates on high hour pumps.
I finally got to the backside of the pump, I found one defective oring, I'm not real sure it's my problem. This pump doesn't seem to have a lot of hours on it to me. Anything else to look at before I reinstall?
If that o ring was leaking it would have been dripping outside the pump. I don't know what happened there. That valve plate looks like a pretty deep groove to me. WRWTexan has way more experience with these than I do. The disc itself is probably available separately but I don't know if you should put a new disc against a worn seat. Is that steel or brass like it looks to me? can you remove the disc and flip it over?
Not sure what the valve plate is? If it's the photo that I'm holding a spring loaded valve, it's steel. I think the oil gives it a gold look. it's also multiple pieces, no groove wear of any kind of depth in it.
Really? that sure looks like a circular groove to me. Part #17 from post 16 is the valve plate or disc, that looks gold in the pic. It was flat when new.
When I get back out to the garage I'll check it out again, I thought that it was two pieces, and that's the seam you see in the pic. the outer ring catches on the three claws and the center is like a spring loaded tappet. I could easily be totally wrong on this, I've never been into one of these pumps before.
That would be new to me. The one I've seen is a flat steel disc (well, it was flat when new, worn with a ring with 5,000 hrs) that seats against the protruding collar inside the pump.
I scrolled through this post rather quick, but didn't see any mention of checking charge pressure. Those rotary pumps need charge pressure to function. Also, there usually.is a manual destroke screw on the stroke control valve. Just a couple things came to my mind.
Okay, you were 100% correct. Here's the pics, the grooves are all uniformed and look machined. Are they supposed to be there? Nothing really irregular
I don't have any charge pressure, for awhile I'd have it but, if I moved anything it would fall off. I do have flow(approx. 3-4gal in 30sec). I figured my problem was on the pressure side but, I'm out of ideas at this point:beatsme
Well, yes the grooves are supposed to be there, this thing is decades old That's normal wear and IMO is not causing your issues. They came flat, think about it, how do you machine that groove, and how do you machine the rounded matching seat? Last I checked those discs were $25 (25pack), but that's not going to solve your issues, and I don't know what it would do if you put flat discs against worn rounded seats.
I agree, I don't feel I've discovered the cause of the problem yet. I guess I'm going to reassemble and start capping off parts of the system to see if I get a change. Anyone have any good ideas? The grass on that side of the driveway is getting long lol!
I forget, have we talked about the pressure control valves (three of them) on the side somewhere?
We haven't, they are on main pump or the drivetrain? I've checked what I think is a pressure relief valve, above the trans pump filter. In the manual there is a basic hydraulic diagram, I saw two potential valves on the output side of the trans pump, haven't been able to locate them yet.
I don't have that model or a manual for it, so I'm guessing based on another Deere model and jdparts.com. Your's will be different. Either the REVERSER CLUTCH CONTROL VALVE or the PRESSURE CONTROL VALVE is where I'd look. My understanding is the transmission pump supplies the oil pressure to the reverser first at the highest pressure, then the charge pressure to the hydraulic pump at a medium pressure, then lube/oil cooler flow at a lower pressure. Did you mention a bypassed oil cooler, or was that somebody else? There are three "relief" or "pressure control" valves-they do the same thing. The first one releases enough oil from the transmission circuit to the charge circuit to maintain the transmission pressure, the second one releases enough oil from the charge circuit to the lube/cooler circuit to maintain the charge pressure. The third one releases enough oil from the lube/cooler circuit to keep the pressure from blowing the oil cooler etc. There are lots of clips, orifices, and even cotter pins in this whole mess that could cause problems. You should be able to locate these valves by comparing the drawings on jdparts.com with the descriptions in the manual and your machine. The service manual is the best way to figure out their function and test procedure.
I didn't mention a cooler bypass, I checked a transmission filter relief(seemed okay to me). Reverser clutch control valve sound like a good place to check, because the machine slips in high gear. I also figure I'll attempt to cap lines to circuits to see if I can narrow the issue down some how. Still not certain if it's a high or low pressure issue. Wouldn't be any fun if it was easy!
I was doing some checking today, my hydraulic pump is back on and, I was able to move the hoe out of the way but, is by no means right. I idled at 3/4 throttle and searched for anything getting hot. The feed Line to the hoe and valve block was around 130f while everything else was 100 to 110. I got the bright idea that I would remove the feed line and cap it. I figured if the loader and steering came back to life I was in business. The opposite happened, nothing would move at all. My question is should I have connected the feed line with the out line in a loop? I figured maybe I just cut flow to the whole system, not real sure what was going on. Before I could try to cap the loader valve I got rained on so I'm not certain what the result of that would be
So you capped the line to the backhoe valve block, and nothing would work then? And everything, trans, hoe, loader, steering, brakes, all worked at least a little before capping that line? I can't explain that, but it could be coincidence also with a machine that seems to have a mind of it's own when it works or doesn't. Uncapping the line immediately and having everything start working would be more to go on. Knowing the charge pressure when it's doing these things might be useful. The only useful bit of info that I can add is that the backhoe and loader return flow (and leakage) goes back to the hydraulic pump charge circuit, but the brakes and steering go back to the reservoir.
Did the tractor even start with the lines capped? Many of the older machines flowed thru the hoe with a power beyound valve bank and then fed the rest of he tractor. They had to be connected to make the loop when the hoe ws removed.
The machine fired pretty easy (twice actually). first time my cap was leaking and there was very obvious pressure behind it. I also noted after uncapping the line a leak developed under the trans around the filter, not real sure where yet because it started to rain on me. Any ideas are welcomed, I'm running out of them! If I thought I could get 6000 for the thing at this point I'd take it. Bad way to be lol:thumbdown
This is a closed center JD radial pump setup. Basically there's a manifold that supplies the different valves instead of all the flow going through every valve in series. Sorry, no ideas on the trans leak. Charge pressure is a good thing though.