Hello, I've got what I think is a late 80s, maybe early 90s?, Mitsubishi FGC15 truck (serial AF81B-51651) that's got a 4cyl engine in it. Hasn't run in 5+ years but "ran when parked". Fresh tank of LPG, put a new battery on it, and the darn thing started up! Drive feels fine, good throttle, but noticed my side shift cylinders have a leak. Where it'd sat there was a stain but wasn't giant, maybe about 8in diameter. I used it for about 15 minutes to get some stuff down from up top but noticed that lifting the mast, it was moving really really slow. Tilt seemed OK though, but is less volume for movement. Side worked but leaked. Adding throttle helped a little but not much on the mast. Over that 15min period though, I was losing ability to lift the forks after lowering back down. Got what I needed moved, parked it. 3 days later (yesterday) I started it up again to move something. Still have drive, but now I don't have ANY movement from the forks. No mast lift at all, regardless of throttle. No tilt, and no side shift either. Nothing. I checked the hydraulic fluid level, seems OK (at the N), however it looks a little milky and maybe foamed/aerated. This thing has been stored/parked inside for 5+ years but prior was parked outside. Engine oil seems fine, as does what appears to be transmission fluid (smaller stick under foot panel near throttle). If it had water in it and had separated sitting for those years, and I ran it, surely it'd already had contaminated oil run through it before it was parked inside. It worked for 15 minutes, but faded off, and now nothing. Not really sure why it'd work initially but not now. Maybe a plugged filter (don't even know where it's at to check). Perhaps after sitting so long the water had separated and I had "good" oil until water mixed back in? Perhaps I have a water contamination issue plus perhaps there's air trapped? Any recommendations on what to do from here? I can't find a manual for this thing anywhere. Perhaps pull lines and purge tank and then figure out how to purge/flush cylinders? I have no idea what I might pay, even ballpark, to have someone come service it either. Any ideas on who I might call in Indianapolis, IN if I decide not to mess with it myself?
I would crack the lines at the cylinders them selves then stroke the function and see if you where getting flow to the cylinders. If you are not getting flow to the cylinders or very limited flow work back towards the valve body itself. Start with the simple things. Make sure the linkages are actually working ect.
Last week I checked the fluid again after it'd sat for some time, definitely low on hydraulic oil and definitely contaminated. I drained the oil and put in new oil to the top end of N mark. Controls came back. But I noticed they still seem sluggish and seemed like they slowed down the longer the truck ran, ie fluid temp increased. I'm wondering if I just have a pump that's worn out coupled with mast rollers that are crusted over with old grease? I was able to get all cylinders fully extended/retracted and deadheaded a few times. I wonder if running a heavier oil would be beneficial. This truck is probably only worth a few thousand I'd guess, no idea what it'd cost to have it serviced if it was a worn pump.