Where are the spool valves on here... From what everyone says I have the bucket spool sticking... I want to take it aprt and try and polish it up. I just changed all oil filters today but I need this to start working!!!
Unless you have already checked the pilot controller it's much more likely to be that than the spool. Is it sticking in both directions? In your picture though, according to the parts book the bucket spool is in that group of four, the spool closest to the center of the valve bank. Have to remove the pilot hose on the left end, if the other three pilot hoses are long enough to remove that cover you can leave them attached, otherwise tag them before disconnecting. There will be some o-rings under the cover but it looks like once you get it off the spools will lift right out, the end you're looking at here has the centering springs attached to the spools I think. Unless you can pull a vacuum on the tank you might want to drain the oil before attempting this. Make sure you clean really well before opening it up, don't need to make more problems by letting any specks of dirt into the system.
Yes to everything Lantraxco said. The bucket spool is the one with no paint on the 90deg fitting. I'm pretty sure you have to remove all the pilot lines to take the pilot cap off. And yes you will drain the tank in a hurry when you pull a spool out.
Good day Oilerman Sorry to the bearer of bad news but if you have a sticking spool removing the spool and polishing is unlikely to resolve the issue. The spool made from a billet of steel is far more likely to survive damage than that of the soft iron valve housing. Valve housings I belive cannot be repaired. If you dismantle the spool take a close look at the spring and guide we have seen these foul the spool movement, this can be fixed without great expense. Kind regards Uffex
Don't know about that particular valve block, but it's not uncommon around here (or at least wasn't back when I was turning wrenches) to hone out the valve body and grind/chrome oversize/regrind the spools to fit. With the advent of these big expensive monoblock valve assemblies they had to come up with some way to avoid paying twenty grand for a valve bank. Still think the first place to check is the pilot controller capsules, unless you have already eliminated that with pressure checks or swapping hoses. :my2c
I know HRD up here in Fife still hones the bores and rechromes the spools with pretty good results. We had it done on our EX700 that had 28,000hrs on it 10yrs ago. Far as I know it's still digging down in Creswell.
Oilerman, what are your symptoms, most times I see stuck spools there is something in there, most common on john Deere are Allen set screws and the locking balls they hold in.
I had a d6n that had a bent lift cylinder and pieces got into the spool valve. I was able to make a home made flap wheel to polish the bore and so far works fine. Jason
Being the bucket cylinder is the most likely damaged cylinder, could it be a damaged cylinder, bent rod, or particle from damaged or loose piston nut?
Well The bucket moves... it just is real slow... I have a video of it on here somewhere... and I have another one for someone else I was showing. I will post them. I had a guy on here. (spitzar) come and take a look at it and we swapped hoses... all it did was make it do the same thing on the other control. Sometimes it lets go and works..but most of the times it doesnt.
https://www.youtube.com/watch?v=JEb25ugGHmg&list=UUvDEGvTyRdpZAh7ZZCKscoQ Funny thing is a few days after I made this video .. I started it up and it was working.
That looks like a resolver or load check issue or something the way it moves from bucket to boom to swing. And the bucket will free fall when you move the control which means the spool is shifting enough to open the port to tank so I don't believe it's a sticking spool. You're not getting pump flow or it's going somewhere else is the issue.
Never heard of a resolver before? Will I be damaging it by closing and opening the bucket using the stick?
I may not be using the correct terminology. Question: do you get any bucket action when using another function to cause the pumps to kick in? The pumps are controlled by a computer, wondering if it's just an issue of the pump not stroking up, or if it's maybe one of the little poppet or spool valves in the main valve block that control flow internally. I don't know enough about the 790E to know the inner workings of the main valve bodies and the pump controls. I doubt you can do any damage by using it the way it is, but I think at this point you either need the service manual or a Deere technician to pinpoint the problem.
No Its all the same weather you use another function or not. Im thinking something is sticking like people are telling me... cause it sometimes likes to let go and work... and then go back.. Trying to get a tech out here is like pulling teeth... well local ones anyways.
I would start at the pilot pressures, put a gauge inline and watch as it happens, sounds like there is no load on engine, hydraulic or electrical, gotta start somewhere. Should be around 500 psi in full travel of control at spool.
So today before I started it up... I took my small hammer and tapped on the valve bank where the bucket spool is and then started it up.... Works!!
Well, I think you may have hit on the problem then, lol.
Check the wiring to the differential pressure sensor(Its that thing in your picture with a little rubber cover and a wire coming from it).That is what tells the pump to stroke.There is also a bunch of check valves behind the valve bank(engine side ) that read the highest work pressure and send that hyd signal to the differential pressure sensor. If every thing all of a sudden works and then it doesn't that sounds like a sensor problem.
Hello I was just looking around to see if there was someone with a similar problem I am having. I recently repair the electrical system on my ex200-2 machine only to have another. It started by the front attachment will continue to move depending on that part you engage despite you releasing the joystick. Later there were slow movements of the bucket, arm and boom it reach to a point now that there are movement with the arm and bucket cylinders but none with the boom while the joystick are being engage. Whenever you start the machine the boom cylinders will automatically move upwards despite the safety lock is on and can only be lowered by the boom relief valve. While the boom is airborne and safety lock is release you can only get joystick response from the bucket and arm but no boom response, there is absolutely no boom up or down from the joystick. Can anyone please guide me in what direction I should take in getting this trouble of my hands
If it moves with the safety on (pilot shutoff,long lever beside door)then you have a broken spring on the boom spool.Or you have had a failure of a cylinder or motor that has filled the valve with metal.Easy to check by removing the pilot caps and pulling out the boom spool.MAKE SURE YOU HAVE EVERY THING LOWERED TO THE GROUND!!! If you find any metal then you have to find the source and remove the valve and clean it out.First pull the filter and check for contamination.
Hello Joeblow today I had a look at my problem. I remove the cover and I notice that the boom spool was lower than the other three, so I remove the bolt and spring for the spool responsible for the bucket and I notice that I can move it up and down with my hands but I just cant get to do the same with the boom spool it was stuck and tight as hell but I played with it until I get it to move freely. I clean up the build up mess from the area re-install and wh-ala the boom didn't move by itself when the machine was started and was able to be control by the joystick. Now this machine when I got it, it was working without any hydraulic filters so I change the oil since and install hydraulic filters but what I have notice is that whenever I and dealing with valves or the springs I mention earlier there is this dark brown build up stuff which is very smooth to the touch I was wondering if that could have cause the boom spool to stick. I will keep looking to see if there are other culprits. I want to thanks for in information you shared with me and may God richly bless you thanks once again man.
if you change hoses to different valve and the same thing happens then you may have a collapsed hose at times
Oilerman, have you figured out why your 790 hydraulics are acting slow? Mine do the same thing.
Hello rkellah it was a stuck spool on the four spool side but that was only one part of my problem later the complete machine couldnt move and there was a clack clack noise coming from the pump so i remove it to realize the the shaft on the pilot pump got broken and later destroy the pump I later bought new parts and rebuild it but still cant it it to move anything i checked all spools to see if ant was stuck clean the tanks change the fillers but still nothing i am now loss. I am not a mechanic nor electrician so i solve some of my problem by trial and error and with my manual and listen to advice from folks on this forum. please send me your email address i will send some information to you