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NC Wayne
09-16-2004 20:31:08
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Hey guys, I know there are more mechanics out there than just me, and I'm hoping one of you might have runn into this problem before. I'm working on a Komatsu PC150-5 that has a hydraulic problem. It started out with the right track not pulling (slow and no power) and the bucket curl/dump circuit having low power. All the control pressures checked out good (PPC, CO, NC, TVC, and charge pump) but everything was simple week or slow. Funny thing is it would travel in a straight line with no problem, it just wouldn't pull with the right track alone to turn although the left one was fine. Long story short the rear section of the pump was bad so I replaced the pump. Now the track pulls like it's supposed to but the bucket curl/dump function still lacks power, and now the boom down function lacks power when it origionally didn't. Funny thing is if I start swinging and then curl the curl function works just fine, and I imagine the boom down would too... but it's hard to pick the machine up when your swinging if you know what I mean.... Too if I let the machine set still and actuate either the curl or boom down function neither will work, but if I touch the left travel peddle, at the same time, and rock it enough to actuate the travel limit switch both functions start to work properly. The service manual has not proven to be a whole lot of help so far beyond the basic troubleshoot and replace items which all seem to be fine just like they were when the thing fell in my lap initially. I have also checked most all of the "extremely common" and "not so common" things my buddies at the dealership say to check. In fact most of the same things I had to check for the initial track problem are what they say will cause this problem as well, but all those things checked out good in the beginning (like one of the travel switches maybe being stuck, which they still aren't) so I'm running out of options here. I even went so far as to call Komatsu America this morning and talk to one of the factory techs. That guy was telling me to check compensator valves that this machine doesn't even have. He was nice enough to fax me a service bulliten about doing a new check to determine which one was bad, I'll give him that much credit for trying, but the front page of it gave all the models it pertained to and there wasn't even a PC150 of any kind listed....Because they don't use the compensators.... As far as the cylinder packings maybe being a problem I wish it were that easy. I had to do the right boom lift cylinder when I first started working on the machine because it was pouring oil out the rod seal. I used the boom several times to pick the side of the machine up to do the track timing tests, etc. before I changed the pump and it always worked fine then, so that pretty much rules that out as a problem now. The curl cylinder is the same way. I had noticed it weeping down when it sat for a ffew days so when it gave trouble, even with the new pump, I figured the packing in it was shot...which it was...so I resealed it too. Problem is the problem didn't go away with the new seals..... Like I said I have pretty much hit a wall with this thing. If any of you guys have run into anything like this before or know of a good Komatsu excavator guy that might know something my dealership guys don't please let me know. My email is Nota55Nomad@AOL.com. Thanks, Wayne
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