Hi everyone, first post here. And I have some questions on a Komatsu pc120 excavator. First let me tell the back story, my uncle is a very we respected welder/machinist/blacksmith in the area, a few years ago, some guys who dabble in dirt moving brought him this excavator for him to redo the bucket pins, and straighten some things, not sure what all but I know it was the braces for the mechanical thumb. After he did all the work he drove it across the street to test it out on some trees in a lit he owned, mostly to make sure everything worked like it should, well after a few minutes of running it, he noticed the engine was warmer than it should be, but because none of the gauges or anything in the cab really worked he hadn't noticed it, he tried starting it after a few hours of cooling and it wouldn't start, after tinkering a while he called the guys who owned it and they come unglued on him, turns out the thing had a small coolant leak but instead of fixing it they just continued to dump coolant in, in fact they carried a 55gal drum in their pickup because it would go through it pretty fast.he had only run it for about 10 minutes In short wouldn't pay their bill, so he sued them and they countersued him, etc, etc, nothing has happened for over 5 years which means it's now his. So were thinking of getting it running again for our farm use and around his place taking down trees and cleaning ponds and ditches that sort of thing, maybe 50 or 100hrs a year. Granted it's not a big machine, but the price is right. None of us know much about excavators but were pretty mechanical minded. The excavator is in pretty rough shape and its older, but theres ones like it for sale on the internet with a rebuilt engine and they're asking $20k. My uncle knows a guy who used to work on Komatsus so that will help. But our big question is assuming the engine is toasted, the question becomes whether to rebuild it or to retrofit it with a 5.9 Cummins if it'll fit, which we have a line on one that will be cheap, but in good shape. Also I'd like a general overview of these excavators, stuff to watch out for, etc. Its an older model that's yellow and blue. Thanks guys
The color combination implies that it is probably a Dash 3. Is the ID tag still on the machine? On those units they were usually on the outside of cab door or just behind it. Does it have the long lever controls on stands out in front of the operator seat? Does it have pilot controls or are there a lot of rods and bell cranks under the cab? There will be a barrel switch on the monitor panel that will have two settings or three settings. Let us know which it has.
I'll have to look next time I'm over at his shop, no ones looked at it since we tried to get it running again after it quit. On the rest of it, to be honest I have no idea what you're talking about, I know farm equipment, not excavators lol. It's got the 2 levers in front of where you sit, I know those are for the tracks, but maybe all excavators have those? The inside of the cab is pretty trashed mostly because it must not have had any glass in it for quite a few years. Forgot to add that its main job around here will be taking out cedar trees up to about 15 or 20ft in our pastures, a lot of our ground is pretty rough for other means like mulchers or skid loaders. Would this be a decent machine for such jobs?
Are the levers on pedistills ? Back in the day they were a good reliable digger,very basic and no electronics which is in your favor.
I was able to look at that excavator when I was over at my uncle's today. Model is PC120-3, Serial is 21862 Got a few pictures while I was there too, let me know what you guys think.
Chicken leg control handles on manual linkages. You will need lots of penetrating oil and grease to get all the linkage joints free again. The machine doesn't have a regular computer as I recall. There should be a barrel switch on the monitor panel that shows S and L. It does have a TVC solenoid that controls pump absorption torque from the engine which is controlled through that S and L mode switch. I don't know if you can find a bell housing that will mate a Cummins engine to the damper case and then the pump. The Komatsu engine is a great engine but very expensive to rebuild. I would probably risk a little work to see how much damage has been done to it before deciding to just yank it out. If it is toast, you might look for a used motor first.
That's kind of the plan, the guy who used to work on Komatsus said hed come over sometime and get the brakes unlocked and get it prepped to hook a tractor up and be able to get it moved closer to the shop so we can fiddle with it more. Anything else we should know about the machine? Good or bad points?