So today I'm operating this backhoe and I already suspect I have an oil aeration problem or similar. There is about 230psi system pressure which I believe is normal for this backhoe. Then all of a sudden pressure drops to flat out zero and tractor applies parking brake. Ideally I would next test charge pump flow with a flow meter. Of course I don't have one of those. The way I see it, I can either go after it at the charge pump or the pressure regulating valve. Any suggestions?
To zero, or to something like 20-40 psi? This is an E and not an SE?
Yes, the pressure is zero. I have a good gauge connected to the system pressure port and have been watching the transmission hydraulic pressure for a few days when this happened. This is a 310E model. I get a 1 psi wiggle when I start the tractor and this is it.
Several questions. You mention aeration. Is the oil foamy when you check it? Is it only foamy when the issue happens? Is the transmission pressure fine when cold and disappears only when warmed up? When the pressure is good does it operate normally with plenty of pushing power?
What was happening: Start tractor and transmission pressure at 230psi. Releasing parking brake would drop pressure for a split second to 180 but right back up. All seemed to work well for 10 minutes or so and then pressure would start acting sporadic. Then changing direction would turn on parking brake light for a few seconds as the pressure recovered and then it would go. Eventually pressure would drop below about 120 psi and parking brake would apply for good. I would then turn off tractor and let it sit for 5 minutes or so. Recranking and tractor would return back to working properly for another time. I surmised that the tractor was building up air bubbles while running and then turning it off would allow them to escape. I did check fluid and saw it running up dipstick a time or two, but when tractor wasn't acting up, fluid checked out looking good and at full mark at idle. What's happening now: I changed transmission fluid and filter. I noticed that I only got about 2.2 gallons out and added the same. Spec says it holds 3.7 gallons. Maybe rest in torque converter? Anyway, after changing fluid and filter I crank tractor and I have the 230psi like before, release parking brake and drive tractor around for 5 or 6 minutes and pressure looks good. Then all of a sudden my pressure gauge drops to zero and tractor applies parking brake. I let it sit for a while and retry and still have the zero. When it was operating normally it did seem to have plenty of pushing power. At one point I put it against a tree and it would spin the tires for a few seconds but power fell off and eventually I lost all pushing power. Didn't have a gauge connected at that time. I checked fluid and it looked kinda foamy and running up the dipstick. I let it sit an hour or so and tractor would go back to moving around normally. I would say that is an accurate statement. Thanks for the help!
This seems to be the case. I'm wondering if I have more than one issue? Like maybe I have lost my charge pump prime somehow + a pressure control problem? Not sure what to do next. I do have the Deere repair and the operation/test manuals for the machine. I thought about removing the filter and then cranking tractor for a few seconds to see if I get any flow into a bucket. Kinda like a poor mans flow meter. Would that tell anything? What would you suggest?
Could a worn out charge pump cause all these symptoms?
Cut open the old filter and let's see what is inside first. What is in it could give us a clue as to where to go next. Usually I would recommend a flow test at this point. Pumps usually lose flow gradually as they warm up, not total flow loss. More likely a problem with the duct plate gasket (that's the plate that the transmission control valve is bolted to), duct plate itself, or maybe the system relief valve which is in the control valve. There is an orifice in the control valve that can give issues as well, but not a total pressure lose. I have seen cracked pick up tubes inside the transmission cause transmission pump to lose prime, especially when hot.
This filter has a little sludge in it for sure. I passed that rare earth magnet carefully across this cut section and got nothing.
Sludge or a fine black paper-like material? Many hours on this machine? Either way it could cause sticking issues with valves. Unfortunately without being able to hook up test equipment all I can do is stab into the dark so you may have to start exploring. I guess I would suggest taking your control valve apart and making sure all the spools move freely and that the screens on the ends of the solenoids are not plugged up with the sludge. While the trans is drained reach in through the drain hole with a long screwdriver and see if the pick up tube is loose or plugged up.
Do you still have hydraulics when the trans quits?
Yes I do. What about removing the filter and seeing if the charge pump moves fluid into a 5 gallon bucket? If I don't see flow there, I know it's charge pump related. Like you mentioned before, seems like we would have at least 20 or 30 psi if a valve was stuck open or gasket blown? I appreciate your help with it.
I pulled the big three solenoids on the side of the trans and the MFWD was the only one that had any of this sludge type stuff on it. Back when I had 230 psi on the tractor, if I switched the machine to 2wd the pressure would fall to sub 100 psi and apply parking brake. Flipped the switch back to MFWD and pressure returned to normal. This MFWD issue could be caused by a sticking valve in the control valve too I suspect?
Yes you could start it without the filter to see if the pump moves oil (spec on that pump is 11.2 gpm minimum at 1500 rpm). Even at idle it could be messy. In reference to the pressure loss with the MFWD - that system has pressure applied to the MFWD clutch when the system is turned off (2 WD). I have seen and there are bulletins regarding trans pressure loss with the MFWD off, caused by a pressure tube inside coming loose.
OK, I'm gonna give this a try. If the pump moves oil (if my math right, should be about a gallon in 6 secs) then I will pull the control valve. If the pump is doing nothing I will go for the charge pump. Let me ask you this. Is it possible to also pull the duct plate while transmission is still in the tractor. I'm guessing pulling that hydraulic tank would make pulling both a lot easier. Looks pretty tight in there. Also, it might be Saturday before I can really dig into this. Still have to work and pay bills I'm afraid. Thank you.
The transmission pump, control valve and duct plate can all be removed with the transmission in the tractor. The transmission pump is in front of the hydraulic pump so that would have to removed. The hydraulic reservoir does not need to be touched.
Thinking ahead, If you think you might be pulling the transmission out at any point, you may want to put the machine up on heavy duty jack stands (37 inches off the floor measured at the bottom of the battery box) while you are working on the pump/control valve/duct plate. That way you do not have to put all that stuff back on to get the machine in the air to pull a trans and it makes working on the other stuff much easier.
That sounds like great advice. I'm going to pull the filter and see if I have any flow first thing in the morning. If I do, I plan to go ahead and pull the control valve and see what that looks like. If no flow, then I'll put the tractor on stands, drain the tank, pull hydraulic pump, pull charge pump and take it apart. Does that sound like the best way to go about it or just go ahead and do the stands first thing?
Put it on the stands after your flow test but before pulling the control valve.
Will do!
Update: Got the filter off and held a bucket under the filter mount and not one drop of fluid pumped out of the pump in 5 seconds. So no wonder I have zero transmission pressure. I'm collecting my jackstands and RR jacks. Hope to get it lifted and hydraulic tank drained today. Thanks.
That is high off the ground, but it certainly does make working on it much easier! As you can see I have a broken tooth on the charge pump. How does this happen? What to do next? Buy a pump and install it and see what I've got?
And the pump wear can be seen with the gears out. I'm starting to think this was the root of all my pressure problems. Notice the wear rings around where the top gear (as seen in this photo) travels. Let me ask this: Can I install a new charge pump and test transmission pressure before I reinstall the main hydraulic pump?
Good Job! Is that the missing tooth off to the right in the one photo? Looks like it which should mean no stray chunks in your system. Unfortunately no, you have to put the hydraulic pump back on to start it. I'm confident it will be fixed. After you run the transmission to make sure everything works OK you may want to change the oil again, maybe even twice more (new filters each time) to make sure you get as much of the fine particles out as possible since you do not have flushing equipment. If pressures are good and the oil is warm perform a converter stall test to verify the trans is OK (3rd gear forward, brake applied, full throttle - read engine rpm)(spec 1900-2100 without turbo, 2000-2200 with turbo). Just don't stall it too long (no more than 10-15 seconds at a time, with a minute between stalls).
Thank you! I'll report back when I have it back together and tested.
I have made two trips to John Deere for these ordered parts and I still don't have them. Maybe they will show up there tomorrow. I have cleaned all the mating surfaces really well so should be good to go when they do arrive. For what they cost, they should have been overnighted no problem!
Unfortunately JL anything other than a stock order (3-4 days) will have freight charges. Keep me posted on the end result.
Got the new charge pump installed and I got 240 psi right off the bat on system pressure. There seemed to be an intermittent low squeal from somewhere that seemed to go away after a few minutes and may not be related. Unfortunately after about 15 minutes the pressure started to fall off to 210 psi or so. I could hear what I think is a regulating valve opening and closing with pressure swinging between 210 and 160 or so. Increasing engine speed stopped that action though. Anyway, eventually the pressure dropped enough to apply parking brake at about 20 minutes of run time. I turned off tractor for 5 minutes and recranked and had good pressure again and moved tractor. I'm changing filter and fluid again right now and I guess the next thing to do is go through the control valve?
Sorry to hear about the pressure still dropping. Maybe some of that sludge in the filter picture made its way to the control valve and causing some sticking?
Got rained out today, but tomorrow I plan on pulling the transmission control valve and going through it. What about the duct plate? What should I look for while I have the control valve out?
Unfortunately you won't see anything on the duct plate with the control valve off. Concentrate on the control valve first. Look at the solenoids and the spools. See if anything is sticky or if any screens on the solenoids are plugged. also look at any orifices that may be plugged as well.
Did you try the MFWD switch when the pressure was low enough to apply the park brake? Try that before pulling control valve.
I did try it when pressure was high and it dropped off. You're suggesting I try it when it's low enough to apply parking brake? I'll try it.
Yes that is correct. If you turn the MFWD on (no pressure to MFWD) and the pressure comes up, then the issue is with the tube feeding the MFWD.
Here is what we have: After changing the fluid and filter I cranked the tractor and it ran properly and maintained sufficient trans pressure for close to 20 minutes. Starting out at about 232 psi and stayed near there for about 10 minutes and then slowly creeping down to eventually applying the parking brake at about 120 psi. Once the parking brake applied I toggled the MFWD (going to 2wd mode) and pressure dropped all the way down to 30 psi. I flipped the MFWD again and interestingly enough pressure did not climb back up. I turned machine off and let it sit for 3 minutes. I recranked it and had 215 PSI trans pressure again but cycling parking brake left brake appled with pressure at about 120 psi. I tried the MFWD switch again (going to 2wd mode) at this point and allowed pressure to drop to about 60 psi, then toggled 2WD back off and pressure did try to climb back up but only made to the 120 psi mark. I'm guessing proceed with control valve removal?
Looking back over the last few posts I realize I need to clarify something. Anytime I try to put the machine in 2wd the pressure drops. Therefore the default position anytime I'm on the machine is MFWD engaged because in 2wd pressure is lost and parking brake is applied every time. Thanks! Note: The fluid that came out of the trans looked as clean as the fluid I put in it. That hasn't been the case before.
If pressure drops going into two wheel drive then there would be excessive leakage in the MFWD circuit. But, the pressure should come back up with MFWD re-engaged. Odd that it didn't. Since you mentioned that the pressure dropped to 30 psi and did not come back up leads me to believe a possible problem with the modulation spool in the control valve. Proceed with the control valve.
I have pulled the control valve and it first glance it looks clean. Here are a couple of pictures of it. The modulation valve looks open?
I'm guessing all new gaskets when I reassemble this?
I was hoping for some smoking gun here, but having pulled apart the modulation and regulating valves I don't see it? There are a couple of marks on that modulation spool, but that doesn't seem to affect anything. Spool slides smoothly best I can tell.
The orifice.
My plan is to go ahead and take this control valve completely apart, clean everything, polish the bores, buy a gasket set, put it back together. What else should I do to it and then what?
Looks good in the pictures. If spool moves smoothly don't worry about the marks. Yes, I would install new gaskets. While you are in there make sure the screens on the ends of the solenoids are clear. Also check that the orifice (item #9 in attachment) is in place and tight. Also make sure the other spools are free as well. If all OK then you have 2 choices. Remove duct plate and inspect or remove transmission and split apart. One more question, at the moment the park brake applied from the pressure drop did you check the oil level at the same time?
What would you do in my spot? I did not check fluid level when the parking brake applied. Wish I had thought of that. I guess we are down to either the duct plate has a blown gasket or the pickup pipe is cracked/loose?
I've been looking at it. Would you say that pulling that duct plate is at least 1/2 as much work as pulling the trans? Here is what I'm thinking. Reinstall cleaned and polished control valve with new top and bottom gaskets. The plate with its rubber gaskets on back of control valve looks fine? Test backhoe to see if I bought anything and check dipstick if/when it applies parking brake. If problem still there and fluid running up dipstick, then go ahead and pull transmission. If fluid stays stable even when brake applies, I don't know.....Then I'm back at pulling duct plate I guess.
If the fluid is climbing the dipstick and your vent is clear, it sounds like there is severe aeration going on in there. If you have the machine in the air like we discussed before you could take the duct plate off and look at the gasket. If nothing found then continue on. I apologize that I don't have an answer for you. It can be a challenge trying to troubleshoot from a laptop without being able to see, hear and feel for one's self. I am impressed with your thought process through this whole thing. I attached 2 JD solutions about oil coming up dipstick or out the vent. It says "G" backhoe in the text of one but does apply to "E's" as well.
Are you suggesting I go ahead and pull the duct plate now or go ahead with the plan I layed out in post #45? I certainly realize its not easy to figure this one out. I do appreciate all you help! I will get to the bottom of it though. Your insight has saved me a bunch of unnecessary work and has helped me to understand how this machine works. I bought this backhoe to replace my 28 year old Ford 3910 farm tractor which I added a front end loader and a backhoe to. I plan to use it to help with the football/baseball/softball fields at my son's school which is across the street from from our house. I'm not in a big hurry to get it going. I work on chassis and shipping containers for a living and this backhoe is sitting beside my house while I work on it. A little about me: I have always been mechanical minded. I have built a couple of V6 outboards, a 5.3L Gen IV LX based GMC truck engine, scratch built a log splitter, air power forging hammer for blacksmithing, etc. I mention these things to say that I believe I can take this transmission apart and put it back together. If you have time to check on me here and offer your advice while I journey through this thing, it would be a big help. If you do not, I completely understand and wish you the best. JL Sargent.
Those documents suggest that cold and before startup, the fluid level should be 5" up from the full mark. That is exactly where mine is, so I do believe I have the correct amount of fluid. I did clean my vent first thing back when I started working on this. Interestingly, I have never seen fluid come out that vent or out the dipstick tube. Let me ask you this. If the control valve and charge pump are both working properly and the parking brake applies itself due to low pressure and there is no aeration up the dipstick tube, does that point to pretty much the duct plate gasket? What else could it be? Now if I have aeration, then doesn't that have to come from the suction side of things? That meaning charge pump feed pipe, o-ring, duct plate, gasket, o ring at charge pump?
First, I do plan on seeing this through to the end. So with that being said I think there is something like a crack in a tube that opens up when the trans warms up. The duct plate could have a gasket partially blown causing the same issue. Cold oil you have pressure and when it warms up and the oil thins and the pressure drops. So if you have aeration, take the trans out. If not take the duct plate out as outlined in your post #45. In the end I think the trans will be pulled. Again, good job.
Thank you! I have to work out of town tomorrow (Thursday), but I plan to work on this Friday. I guess I might as well go ahead and pull that duct plate friday and see what we have. The main hydraulic pump, charge pump, and duct plate will eventually come off anyway if I have to pull the trans. Might get lucky and it be that gasket, but I doubt it I wish there was a way to take a bore scope and look at that tube in the trans. I'm guessing it's ok to pull the trans with those things (duct plate, charge pump, control valve) already off it?
In my experience with the pick up tube being cracked it was usually cracked near the top so that might be difficult getting the bore scope up there. Worth a try if you have one or know someone with one. If there is an issue with the pressure tube for the MFWD you would probably see that with the scope being that tube is near the bottom. Yes you can pull the trans with that stuff removed. I'll be leaving for vacation Saturday so I will be unavailable for a week. I'll check back with you when I get back to see how you made out. Hopefully with the problem solved!!
We got a big rain last night and it dumped 1.5" of water here. This made working on the backhoe tough and I spent a couple of hours just drying and cleaning tools. I did manage to drain the hydraulic tank and disconnect the hydraulic pump. I've gone through the control valve and have it mostly put back together, waiting on that bottom gasket from Deere. I did go to the Deere dealership and talked to the service writer. I mentioned what the backhoe was doing and he said that even a clogged pickup screen could cause the problem I'm having. He said there was a baffle in the transmission that can come loose and that is what rubs a hole the tube sometimes. I plan to continue tomorrow pulling the charge pump and the duct plate to have a look/see. Barring some great discovery with that, I will continue to work towards pulling the transmission. MG, I hope you have a great vacation week! Yes, hopefully when you get back I will at least have the trans apart and on my way to repairing it. I'll post pictures of whatever I find.
Thanks. Yes there is a baffle around the MFWD clutch pack. The pick up can been seen through the drain plug. More likely maybe something floating around (like a piece of the baffle?) because you said you shut it off and restart and have pressure, like something falls off the pick up and then reattaches. See you in a week.
I've removed the duct plate and the gasket is pictured. There is a small piece missing where the charge pump mounts, but I did that removing the plate. I don't really see any tears or other damage to it. Time to pull the trans.
Wow, a picture is worth a thousand words. I used a bore scope inspection camera and looked down the charge pump feed pipe. Look at the pickup screen! Is there some way to clean/flush this out without tearing down the transmission?
Also, the transmission is drained in these shots. There is still fluid pooled in the bottom of the screen! I can only imagine what the OUTSIDE of this screen looks like. That kinda looks like some kinda growth?
Here is another one.
Tomorrow I'm gonna try to clean that sludge from the pump end of that tube with diesel fuel and a air gun/pump/something. I plan to catch everything from the drain hole in a paint filter to see if I'm making progress. After a while I'll rescope it and we'll see. Might get out of pulling the trans yet!
So after two hours of back flushing charge pump feed pipe with diesel and air power I have this.
What the hell is that?? Some sort of algae?? Looks like you did a great job cleaning it out, whatever it is....
I suspect that at some point in this tractor's past it sat for a while and a small amount of water collected in trans. Then maybe some algae grew. Once tractor was cranked again the algae was pulled to the screen clogging it. Then some friction material was added to the clog. At some point it started starving the charge pump and that caused the fluid aeration problem. That's when I bought it.
Lucky you!! Well you're doing a great job getting her back on her feet again, I've been following since you started, seems like you're real close now.
Hey Thanks, It's been quite the adventure so far for sure. I went to John Deere today and ordered the duct plate and control valve gaskets. I showed the head service guy my bore scope photos and he seemed impressed. He said "I bet it works much better". I cleaned on the screen some more today. I found a way to take a picture of the entire screen and it shows there is still some stuff in it. So that first "clean" photo I posted is a little misleading. I may have one more go at it before I say enough. I'm thinking that's about 85% clean?
Update: I cleaned on that screen one more time and I have it 90% + clean I'd say. Today I installed the duct plate, the control valve, charge pump and the main hydraulic pump. Tomorrow I finish up a few loose ends such as plumbing the main hydraulic pump and install test port fitting for pressure gauge. Then all that's left is filling the main hydraulic tank and the transmission with J20C spec hyd/Trans fluid. Keep your fingers crossed. Hopefully this has us back up and running.
Hallelujah! Not only did I correct for the aeration problem, but It also gave me back the 2wd/mfwd function. Switching to 2wd apparently was a tough load on the previously starving charge pump. All is well now as you can tell by my 250 PSI transmission system pressure. Releasing parking brake only wiggles it about 2 psi and going to 2wd does drop it to 240 psi. MG thanks so much for your help on it. I certainly got to know this transmission on personal basis during this journey.
Great job JL. I hope you get many years of service out of that backhoe.
Thanks again! I've been thinking about that squeal I reported hearing after installing the new charge pump (but screen was still clogged at that time). I have a theory about that and wonder what your thoughts might be. I suspect that the squeal I was hearing was air being sucked in around the o-ring face seal of the intake side of the charge pump. I had drained all the oil out of the transmission before and let it drain for a couple of days so feed tube probably was completely dry. It took 5 seconds for pressure to start rising on the gauge with that new pump. I really think it was sucking air around that o-ring. 75hp engine turning a brand new charge pump pulling against an almost completely stopped up pickup screen? I believe it could be the case. Anyway, with the screen cleaned I had some pressure showing in about a second so much quicker. Hope you guys had a great vacation?
Vacation was great, thanks JL. I assume the squeal is gone now? Your squeal could have also been caused from the pump pulling a hard vacuum against that clogged screen as well. I hope the transmission is working well in all gears. It is hard to tell looking at the picture and without actually seeing it and touching it but that debris looks like clutch material. Hopefully not. Double check transmission performance by performing a converter stall test (third gear Forward, foot on brakes, full throttle) when the transmission is hot (150 +/- 10 deg F). Spec is 2000-2200 rpm w/turbo, 1900-2100 w/o turbo. If in spec your good to go. If it is high then there might be clutch slippage.
I don't have a tachometer unfortunately. I did put the backhoe against a tree and it spun the tires no problem for maybe 5 seconds before I let off the accelerator. Engine was consistently loaded during that test. The screen debris feels organic. It doesn't feel at all like a clump of sand, which is what I imagine clutch material would be. It squishes between my fingers and I can rub it down to nearly nothing. Only when the mass of it is gone and my fingers are touching, can I feel any grit in it at all.
If the clutch material is paper, then yes, this definitely could be that. Now that the diesel has dried from this it is paper light. these are small thin flakes that I can mash and kinda crumble but not really gritty. The lighter colored organic looking "sprouts" that you can see in the photo are now gone.
Jl,Been following your post.Congratulations on the fix way to stick with it.It is such a great feeling to finally call it good and each time a person has to deal with a breakdown he gets that much more familiar with his equipment. May you get many hours of trouble free work out of the 310.
JL. The clutches are a paper/fibrous material, not a cintered bronze like some engine clutches.
MG, thank you. Fortunately it seems to working fine. I need to buy a tachometer. Your avatar, is that in a big Deere tractor?
You are welcome. It's in a small JD 344K wheel loader.
So it's been about 10 days and I've had the opportunity to work the backhoe pretty hard. After an hour or so of work using 3rd or 4th gear can cause the transmission clutch to slip. 1st and 2nd seem to be rock solid though. I haven't detected a slip in those at all yet. I'm guessing it's just a matter of time before it starts to slip in those gears as well? So eventually I will be pulling the trans and going through the two clutches at least. I have a question or two about that. Since I just went through the control valve and I have a new charge pump installed, could I pull the trans and split it without even pulling those again? What am I looking at on this job? Thanks!
No, you do not need to remove those components again. You will need some good pullers to be able to disassemble the clutch packs. A press to go back together.
And have the trans positioned as shown in the picture when splitting (converter side up).
OK, that looks pretty straightforward. I do have a 30 ton press and pullers up to 17 ton. I also have a bearing splitter as shown in those photos. Everything seems real smooth when operating the tractor. I'm hoping the clutch steels are all still straight and not warped. Of course I will replace any that are damaged. I do not let it slip but for a second or two and shift down. I'm not in a hurry. I wonder how long I can go with it as is if I kept it in 1st or 2nd before I have to do this work? If I'm careful, could it be a year or two? Or is only a month or two more realistic? Just curious, can a good JD tech pull this trans and have it split in 4 hours? Bet it takes me a good 8
I'm getting too old to even think about doing it in 4 hrs!! I think it will take me that long to stretch out the kinks in my muscles from the day before
I know what you mean. I twisted my ankle at work a week ago and I'm still hobbling around.
I have to say learned a lot from this thread!!!
Me too! MG really helped me work through that. For an update: I've been using the tractor quite a bit and it is still strong going in the lower 2 gears but only usable in 3rd or 4th when the tractor is cold so I rarely go to those. I'm not in a big hurry. I've been clearing trees (several hundred) so far, landscaping/grading, tore out a wooden floor system, and made 3 trips to school for various backhoe type jobs (IE: moving/spreading gravel, moving weight equipment, storm water control) there. All in all, it's working well if I can stay out of 3rd/4th gears. I keep an eye on transmission fluid condition and level and it continues to be pristine looking and at correct level. Eventually I will pull trans and replace the frictions but it's anybody's guess when that will happen. I've bought 4 new tires this week and I hope to mount those this weekend.
I have seen this happen a few times. The charge pump drive shaft breaks in 2 pieces. It can be pulled out of the converter by just pulling the charge pump. But getting it back in is a trick. as the shaft has to go in with the pump at the same time to get the splines to line up. The broken shaft can be pulled out usually with magnet or drill and tap if you have to..
I guess something eventually has to give. Mine broke the pump gear, but the shaft was ok. Mine continues to work fine in the lower two gears. Eventually I will be reworking the clutch drums, but not until I have to.