Got a 2008 980 h with strange bucket issues. Rack and dump seem to want to do whatever they want. The odd time the bucket will work as it should but only for one or 2 scoops. Recently replaced lift pilot solenoid valve, noticed the pigtails for the rest of them were damaged so I replaced all harness ends. The issues where present before doing this work. I don’t think this is an electrical problem however I could be wrong. Seems almost as if the dump spool is sticking.
Sounds like the pilot modulation valves are sticking. You could try cleaning them.
Yes.
A loose piston on the cylinder rod can have the same symptoms.
The moment the engine is started it curls down / dumps. Hydraulic lock does not stop this issue aswell
Could be stuck main tilt spool by the sound of that. Block the loader arms up, take the cover off over the valves. Remove the tilt spool end cap. The larger cap is the one with the centering spring. See if you can move the spool by hand. Also make sure the joysticks in cab are centering. If you start it without them centred the machine will usually lockout the hydraulic system so I doubt it’s that.
To me this is what I think too. I’ve never really worked with spools before so I’ll say i am a little gunshy to play with them
If you can you should pressure test the pilot signal to the spool first. The spool check is pretty simple. Follow the lines from the tilt cylinders into the main control valve to locate the tilt spool. Remove 2 bolts from end cap and pull it off. You will see a big spring capped with an endbolt so it won’t fly out. If you grab the spring you should be able to easily slide the spool out of the valve a bit. Make sure the bucket is blocked up as it will free fall. If it won’t slide out it’s probably jammed with something on the lands.
I should be able to test pressure. Do you know what pilot pressure is on those machines
Pilot pressure is 500 psi. You can check each spool supply pressure. There are pressure taps on the lines. There should be 0 pressure at the spool end caps until you move a lever. Control pressure of the spool will be around 350 at full stroke.
See the attached.
Nige beat me to it. You can see the test ports for each spool in this pic.
Hello and sorry for the late response. This problem got put on the back burner for a little bit. However I checked and confirmed pilot pressure it was around that 330-350 range if I remeber correctly. Anyways no dice on any of the solenoids being the issue so I moved to pull the cap off of the spool as you suggested and I found something interesting . I don’t beleive this is normal and definitely could pertain to my issue . Any advice moving forward is greatly appreciated
The spool to push on is rock solid however I couldn’t remeber if I was supposed to push or pull on it
Hmmm. Interesting. Can you post a better (more in focus) photo of the denris stuck to the magnet please. When the photo is enlarged I can see your fingers perfectly but the debris is out of focus. Try taking a photo with the debris on a sheet of white paper, maybe with a ruler alongside them for scale. You should be able to pull it out slightly with relative ease. BEWARE : Note the earlier comment by @Mobiltech
Hard to tell but did that material come from wear on the end cap itself. The only way it can get into the end cap is from the pilot system. I doubt very much that it came through the solenoid valve. I would focus on getting the spool to move. Remove the end cap on the opposite end of the spool first then try rotating the spool.
Thanks for the new photos. Not definitive but it almost looks as though something has been "shaved off" somewhere. WAG the tilt cylinder piston maybe.? Were there any reports that the tilt cylinder was drifting on its own when the control was placed in the HOLD position before this control issue started.? Basically for no better reason than the fact that the tilt cylinder is the first thing in line with the control valve spool and that's where any debris would end up. If the spool is jammed by one or more metal particles it would seem logical that they came from the main part of the hydraulic system somewhere. Maybe remove the end cap from the hoist cylinder section of the control valve and check for debris there also, then check if the hoist spool rotates and moves smoothly back & forth a little.? I would also suggest to remove the hydraulic filter and cut it open to look for smaller particles. That will give you an idea of how much contamination is circulating in the system.
the cap is scratched up but i tried my magnet on it and i cannot get it to stick so i beleive it is aluminium So the hoist circuit does still work, but i still plan to look into both caps with my new discovery however with the lever for rack and dump in hold the bucket dumps itself so to answer, yes the bucket does drift on its own when the control in the cab is in hold position. as soon as the engine starts
A wise move to at least check it. In that case I would suggest to remove the tilt cylinder, or at least remove the piston/rod assembly with the cylinder still on the machine, whichever is easiest in the current situation, and have a look inside it.
Any thoughts on the MCV? should it be removed as well?
I imagine it wouldn't hurt. however initially my thought would be concentrated on finding exactly where the slivers of material came from. Once that is known you would be in a better position to formulate an action plan to clean up the system and define where you need to look. A pertinent point would be that with every hydraulic component you open up there is the possibility of introducing contamination from outside into somewhere that didn't have it before. The question to ask is "Do I really need to open this up.?"
Considering the fact that I he tilt spool is seized in the bore I think you will probably be pulling the mcv apart to clean it up and get it moving. A 980 will have 2 tilt cylinders and the barrel end has pressed in tapered caps that require a very large fine thread bolt to press out. I would suggest just pulling the pin on the rod end and sliding the rod and head out of the barrel right on the machine to inspect the seals.
So here is my update, the hoist spool moves very freely. i never got the cap fully off to inspect for debris however, i still will take it fully off after saftying the loader arms (Had a small scare but i have everything blocked up just gunshy) I managed to get the tilt spool to move but god is it ever stiff , no debris in opposite side cap. i'm waiting for the filter to drain here now so i can cut it open and see if anything has gotten to the tank.
what do you guys think of sticking the borescope down the cylinder line holes? I'll be honest were a small family run business and i just don't like the idea of disturbing the seals unless absolutely necessary
Hoist spool side
so the spool side also has filings. however much more . the funniest part is that the hoist spool moves very freely rotates freely in the bore
My bad. Could have sworn it was a single tilt cylinder. With the current cylinder orientation as per the way the front end of the machine is blocked up in your photos you could try sticking a borescope in the rod end of both cylinders but you may not see anything unless you can find some way of draining the oil out, and even then you may struggle to get the borescope in through the oil passages in the head. I agree with the suggestion of @Mobiltech of supporting the rod end of each cylinder, pull the rod end pin then slide the rod/head assembly out of each one for inspection. At worst it will cost you an O-Ring and a backup ring for the head/barrel joint on each cylinder.
I just looked at a picture of a 980H that I worked on quite a few times and only 1 tilt cylinder. 988H would have 2 tilt cylinders. That is my experience. Maybe I am wrong. Simon C
Oops I am wrong. It was a smaller than 980 loader. Just found a real picture and yes 2 tilt cylinders. Owner would know. Simon C
I'm still not sure how all those filings could get in the endcap. They would have to come from the pilot system because the spool lands won't allow oil from the tilt cylinders into the end cap.
I think your onto something… I’ve been thinking it over and I’m starting to think the same
Having slept on it I think @Mobiltech is right. The location of the debris in the end cap would suggest that it came from the opposite direction to the cylinders. The presence of debris in the same locations on the hoist side of the MCV (despite the fact up to now the hoist function apparently does not have a problem) would seem to confirm this.
can that spool pull out of there in the machine ? Does anything else need to come off to pull it out or can I just pull it straight out
I would like to take this cover off but I’m unsure of what’s behind
I have never had luck getting the spool out with the valve installed . I think you will have to remove it. Removing that cap shouldn’t be a problem.
Our 966G tilt spool wouldn’t slide out without hitting the frame so we had to pull the whole thing, i see yours looks pretty close to coming out though! Ours had some scoring and we tried to clean it up so it moved freely, and we did but then the tilt bleeds off. So we have one on order, They only sell these MCV as entire units due to the machining tolerances. So be careful if you are trying to save it $$$ View attachment IMG_1749.jpeg
Regarding disassembly of the MCV the attached might come in useful. If you want any parts breakdowns please ask.
I’m going to pull and assess but I’m hoping maybe to gently polish it but we will see. New MCV from cat is 21k anyways so I am trying to be cost effective. But also need the loader to function best as possible
If you remove the MCV from the machine do you have somewhere that you can fix the body securely in order to attack the seized tilt spool.? As a thought is it possible to unbolt the valve then turn it 90 degrees and use some of the original bolt holes to fix it back to the machine frame and hold it in position.?
Newest discovery’s
I may have won the lottery. Considering it landed in that groove . But how do I evaluate the condition of the spool now
Better shot
From the photos you have posted it doesn't look that bad. How about some close-ups of any areas that are scratched.? Smooth off any irregularities with Scotchbrite or something similar.? What does the bore inside the valve body look like.?
Bore inside does look good … however very hard to see inside spool doesn’t look bad in my honest opinion
Looks good to go. Put her back in. But now you need the find where the piece came from. Is the piston retaining nut coming apart?