Hello all, new to the forum, but just wondering if I might be able to get some diagnosis help? I have very specific symptoms that I'm hoping someone smarter than me will be able to pinpoint straight away... I have a Komatsu 2000 model PC128uu-1 which out of the blue stopped working properly at the end of the day. I parked the machine, pulled the hydraulic disabling lever to climb out, decided to swing machine around a bit further to make getting back in easier, but noticed hydraulics were suddenly exceedingly slow. Didn't think much of it (assumed disabling switch/solenoid hadn't fully switched) until starting it in the morning and it was the same. Hydraulics so slow you almost had to line up the boom against the horizon to see it moving.... Played around with it a bit, and noticed the blade still operated normally, and if you pulled right track lever, everything else would suddenly act normally (except tracks). Used it for a couple of minutes (while holding track lever) to see if it might suddenly 'come right' (maybe some contaminant come unstuck out of a valve or something), only for it to suddenly start tracking full speed with the right track even when track lever was released, and all controls working at over power (scary, as I had a vehicle parked close on each side of it). I have been able to repeat all the above symptoms several times, although I can't predict which 'mode' it will be in when I start it (snail, normal or crazy). Have since found that in 'crazy' mode, the right track will stop tracking if I push the left track lever forward (or use hydraulic disable lever). Also noticed if I use hydraulics at all when it's in this self tracking crazy frame of mind, it is as though it is being over pressured - no fine control, and any slight ram weep becomes a torrent. I have checked and cleaned switch at disable lever, disassembled and cleaned track lever controls at floor (thinking at the time one could be jammed both ways at once), and undone several hoses (especially track related ones) in control valve bank, hoping any foreign material that could have made it down there might come out with fluid... but to no avail. Am suspecting a jammed valve somewhere, but hoping someone with a bit more knowledge might be able to help me narrow down where to start looking, seeing as these symptoms would have quite a few telltale signs in them... Much appreciate any help.
Sorry, correction to the above after starting machine again to re-check symptoms: in 'slow' mode, machine would work normally if Right track lever was pushed forward, and in 'crazy' mode, right track tracks in reverse with full power (will stall engine at low revs), unless I either PUSH or PULL the RIGHT (not left) track lever. Sorry if I confused the issue a bit...
I have a workshop manual for the machine, and can upload pictures from it if it might help someone put the pieces together... Really appreciate any help in pointing me in the right direction.
You need to pull the hydraulic filter checking for brass and steel debris stuck in it. A photo of the pump might be helpful. What I have seen over here is the PC128US-2 and I'm not sure if they are the same hydraulic system.
Thanks John, I have pulled the return filter, which looked very clean, then pulled the suction strainer, which had no signs of metal at all. There were a few bits and pieces in it of what looked like some kind of plastic (2 or 3 pieces about 1-2mm across). I also dragged a magnet across the floor of the tank, and got a slight stain of metallic particles on the end, but I was surprised how little. Certainly no 'furry' particles on the magnet. I can't get a really good picture of the pump, as the counter weight is on the way, but have sent some from the manual. I'll send what I've got of the actual pump in the next message.
Here are pictures of the pump and the control valve bank. Thanks again for any clues...
Does this machine have a Dash 6 style monitor panel in the cab and if you have you checked it for codes? The valve is definitely and Dash 6 CLSS valve. I don't recognize what little can be seen of the pump. It does have pilot pump though. How many hours on the machine? I hope you don't mind my questions at this point but I'm trying to get a feel for the problem and just what your machine is.
Thank you John, and any questions welcome as it helps get to the bottom of the problem... I have seen both C1 and 61 come up on the display - sorry, should have mentioned that in my original post. Not 100% sure that either of them weren't showing before the problem started. 61 refers to LS-EPC solenoid system, and C1 refers to boom raise and lower pressure switch input being the same.
Sorry, forgot to answer the question about hours, it's done only just under 4300hrs from new. I've had the machine for about 3 years, before which I had a 1999 PC50uum-2, which had exactly the same instrument panel, many of the same body panels, etc.