Hey all.. am new hear and have a couple of questions.. I have an 843 Bobcat that I have owned for twenty years ,,, nice clean old machine that currently not moving snow very well,, Problem is bucket is NOT returning to normal (rest) position after dumping. Started with it not returning very fast and then slower and slower after maybe eight to ten dumps. Dipstick says full and clean with never any sign of moisture. Temps here in Michigan have been anywhere from 18 below to highs of maybe 33 for the past couple of months. All other hydraulic functions are perfect (including dumping; tho I realize I got gravity workin there),, Anybody experienced ICE in bucket control block?... Thanks, Walt~
Welcome to HEF dragonslayr. :drinkup Have you got the auxiliary hydraulics engaged or partially engaged? This will affect loader functions.
Thanks for the welcome Willie,,,, I do Not have the auxiliary engaged ,,,thought about that at about three AM and just checked to be sure because you reminded me.. You ever had any trouble with ice?... Thanks again, Walt~
Well, I've never had a problem with ice in the system, but then, we rarely see temps like you describe. So you're saying you can load the bucket with snow, raise the loader arms, dump the bucket, but then bucket labors to roll back up, no?
Weve seen ice in the spool caps up here. Do you have full power rolling back when loaded or is it slow or weak also?
Was thinking the same thing AndrewC, plenty of times I've pulled the centering spring caps off to replace spool seals and have seen water in the caps. In extreme cold this could be a problem, but in my area it doesn't get cold enough for me to know. I would think that if the machine and the hyd oil gets warmed up it would help melt frozen water in spool caps, but again I don't know.
I had a s185 with water in the bics valve and it would freeze up and lock out that function. It never dried itself out, if its cold enough I guess it could it could do weird things. We've had a pretty good cold snap and we are seeing a lot of graders with ice in the spool caps and causing weak and no functions. Usually on machines with snow wings.
I have to yield to your experience there, it doesn't get cold enough to have those effects here, but I can see where it could be a problem.
Hi again and thanks for the responses guys,,, sorry I wasn't clear,,, Yup!, Willie's got it right except for the "labor" part: ALL hydraulic functions are completely normal EXCEPT for returning bucket after dumping.. I first noticed that bucket was returning a little slower after dumping and then got slower and slower until I COULD NOT RETURN IT AT ALL, (does not labor,,,doesn't move at all),, , I finished pushing snow with the cutting edge pointing straight down and got it back to the barn and covered with a tarp with a light under it to try and get a little heat in the bucket control and also change the filter. Thanks again guys,, please let me know what else you might be thinkin, Walt~
How is your bucket foot pedal action, does it work freely in both directions? Or does it feel stiff or feel like the pedal won't go back in the bucket tilt up position?
Hi Willie... foot pedals are completely normal too... first place I looked in fact,,, I have in the past had melting snow turn to ice under the pedals and had to pour hot water to thaw and was hoping it was something that simple but am getting full range of motion without any restriction thanks again,,, W~
Then it's not likely that ice is the problem. Given the machines age, the first thing I'd check is the bucket tilt cylinder. A bad piston seal in that cylinder can cause your problem, and cold weather makes a poor seal even worse. Since the bucket won't tilt up at all, we can test the cylinder by blocking the cylinder ports and see if the cylinder drifts out. Instead, you need to disconnect the hose connection to the barrel end of cylinder, not the rod end. Use proper JIC male plug to plug off the disconnected hose. Connect a piece of hose to the disconnected fitting on the cylinder, like a piece of heater hose slipped over the fitting, point the hose into an empty bucket. Start engine, engine at idle, and tilt bucket up. If the bucket does not tilt up, yet you have oil coming out of the hose into the bucket, the piston seal is done and needs replacement.
Thanks again Willie,,, if I can get any heat out to the pole barn so that I can work, I will do exactly as you suggest and will post my results... May take a couple of days before I can even get back to this project,,, Thanks again, Walt~
what happens with engine off and try to roll the bucket back with loader arms in float?...... set it on the ground, or if its broke over center may have to raise it high in the air with the edge resting on something and then turn engine off and push pedal to roll bucket back and loader arms down at the same time, i would think this would be a simpler test of bad piston seal rather than removing hoses pj
Thanks PJ... I actually did pretty much what you're suggesting when I parked it last,,, at that time; with the cutting edge straight down with some weight on it, I tried backing up with the peddle in up-curl position and it would not return,, also did this with peddle in free position and was the same... I ALSO shut it down with bucket resting so that it could come back to rest position overnight and it is still basically "locked" in the edge down position..... am workin on other broke stuff today but am going to try and get back to this in a couple of days if I can get everything else caught up with,,, thanks again, Walt~
Sounds to me like the piston has came off of the rod.
only having a single tilt cyl wouldnt it fall completely apart with the rod coming completely out of the bore ? pj
Not necessarily. At a point of tilting forward the coupler would be at full radius yet not be enough to allow rod to come out of the cylinder.
If the piston was off it should roll back with down pressure on it. I think it has to be in the control spool or linkage.
Thanks again guys... I decided to spend a few minutes with the 843 quandary so went out and fired it up and thought I'd just try again to get bucket back to "rest" position and surprisingly (to me), the bucket DID slowly return to normal "rest" position....I experimented a couple of times with dumping forward and then returning and could see that it was beginning to slow in return so set it back down in full rest position so that I can now at least use the bucket like a plow,,, Already located a piece of 1/4" plate to tack in place until I can make room to get her into my shop! Does this not tell us that the rod has NOT come off the piston? And does it (POSSIBLY) indicate anything about the possibility of ice obstructing flow?...Sorry if my questions come across as lame but obviously have NOT spent much time with hydraulics and don't have much room to tear into this project... Thanks again, W~
was the engine running when you was able to get it back to flat i would imagine by depressing the pedal to the roll position ? if so that eliminates the possiblity of bad piston to rod connection.....right ? and BTW no your issue and questions are not lame thats why we're all here ...... that and to jump on the possibility of striking it rich by reading spammers post haha pj
Yes, that does confirm the piston has not come off of rod, but I still think you most likely have a poor piston seal. I really doubt ice is your problem, unless the oil is laden with emulsified water, but then you'd have other problems than just bucket tilt. If you've managed to tilt the bucket back to level, we should test the cylinder for drift. Raise the loader arms a few feet with bucket level, stick a floor jack under the front of the bucket and jack up. Once bucket is secured by the jack, disconnect both hoses from the cylinder and cap the fittings with proper JIC plugs/caps. Release and remove jack from under the bucket. See if the bucket drifts down and how quickly, minutes or a couple of hours. If it drifts down fairly quickly your piston seal is bad.
dont mean to argue but wouldnt he just need to cap the lower fitting on the cyl and leave the top one open ? with the reduction of the rod and both ports capped it would try to pull a vacum on the hyd fluid and essintially have no travel ?? also why the floor jack couldnt he just cap it and lift the loader arms ? pj
You do not want to cap both ports with the rod coming in . The oil would have to come out past the rod seal for the rod to go in with both capped. If the rod is going out it would create a vacuum in the cylinder. You would only cap one port at a time for this test. Also if the cyl is leaking past the seals the bucket should roll back if you put loader arm down force on it while holding it in tiltback mode.
The rod will be extending while drifting bucket down Mobiltech, and it will drift down with both ports capped, have seen Bobcat tilt cylinder do it many times. But option would be to leave the cap off of the barrel end port and cap the rod end port, it will simply leak oil from the open port.
Want to add a couple of late evening observations and ask another question: Last thing tonight I decided to make some room to at least get the cab/roll cage swung back and take another look at the pedals which I had de-iced earlier today and I think that even tho I had not noticed it in earlier inspection that the return (heel) pedal seems to NOT be moving back (down) as far as it should be. What I am basing this on is a wear mark on the linkage that disappears into the hydraulic drive compartment under the seat which looks to me like it should really be traveling rearward another 1/2" to maybe 3/4". Don't want ya to think that I been lax but really did not notice the pedal NOT have a full range of movement. Any further thoughts?... Thanks, W~
That changes all above comments. :yup
That's what I was thinking,,, any new thoughts? Still below zero here and am workin inside for another couple of hours but am then going back out and see what else I can find. Do you think there could be ice in the bucket control block? I am gonna (TRY) and get some heat in there and see if it changes anything. Thanks, W~
Sooo... I did go out and apply some heat while my buddy chiseled ice and did finally manage to get the bucket to return and now it seems to roll forward slower that it had,, could we have just transferred a piece from one side of a spool to another?,,, Me and my Bobcat have had enough of this winter,,, Thanks again for all the help, W~
You need to take the spool cap off of the rear of the bucket tilt spool, probably have some crap in there obstructing the centering spring operation.
Thanks again Willie.... am gonna try to get this machine inside my shop so that I can get at this,,, I will post again as soon as I can do what you suggest, Walt~
Just working with the info you provide. You describe it's changed, now bucket dump is having an issue. This would have to be either something wrong with pedal, linkage between pedal and valve spool, something stuck in valve spool (hope not), or a problem inside the spool cap obstructing operation of centering spring (which does happen). I hope you get it sorted out.