Just looking to spitball ideas off other people for pointers on this. Its a 99 1845c (last series) skidsteer with about 2k hours on it, always barn kept so no rust or anything. Anyways its hydraulics have always worked fine, but I parked it, shut it off and hopped out to open a gate, when I got back in it it was making a loud hissing sound out back, determined the hissing was coming from the loader valve which was concerning. When I got back in cab, steering was fine, bucket curl worked fine, and the loader would go up, but when I tried to get it to go down, it would go up, reversed of normal operation. if you just cracked the controls 50% of the time it would go down, 50% go up. If you curled the bucket, while curling it would go down when control was pressed to go down. I drove it probably 10 mins to get it back to shop, and while trying to lower the loader to fit in door while curling the bucket the system apparently dead headed and blew out a hydro line to the auxilary hydraulics. the line that blew out wasnt the supply line to the aux valve from the main valve assembly, but the line that went out of the aux valve going to the loaders connection for attachments. The only note on aux is that they have never been used while here except for this last oct used them for 30 mins on a rented trencher, but that was about 40 machine hours ago I suspected and some case dealers agreed that it seems like something was blocking the up down valve and causing fluid to bypass, my guess was a oring going bad so removed the valve assembly and tore it down. Problem is there didnt seem to be anything damaged or falling apart upon teardown so not obvious like hoped. Ive been doing some reading and Im wondering if something could have been floating around, or if something in the aux valve was failing and causing the issue somehow, especially given hose that blew out was past the aux valve assembly which as far as I understand should have been shut preventing fluid from bypassing it. The lift valve does have some additional stuff on it, 1 bypass "popet?" with springs and the chrome rod has additional holes machined into it that could clog as well. Any help or thoughts to help point in a direction would be greatly appreciated as wanted to plan next move
Not having worked on a problem like you have, I did have a similar experience with one of my 400 series. I had pushed down on the aux outlet petal partway and that messed up the loader functions. You may have done the same thing.
So follow up, it ended up being the aux pedal valve, it has failed seals that had cause huge amounts of corrosion and build up in the spring assembly. Some of the bottom metal cup was over 50% gone from corrosion. Apparently I must have glanced the aux valve when getting out, and the spring was so gunked up that it was not able to return to the neutral position. Also found out the loader had a similar issue with its float detent that the spring assembly was completely corroded over and was not able to function with its float. New screws, springs, ball bears, and resurfaced detent and everything appears to be sliding in its positions well now