I just bought a 96 PC50uu2 excavator that seems to have a lack of power issue. We noticed it when trying to push our stuck dump truck out of a ditch, the truck is a small ford f800 five yard that was empty at the time, and the excavator couldn't do it, it would not spin the tracks, just seemed to not have enough power. This size machine should push that small truck out of that situation no problem. We tried putting the bucket against the truck and pushing with the tracks, no dice, then we tried pulling the machine close to the truck and pushing with the boom, no dice,..... so the power issue does not seem to be isolated to the tracks or boom. Also noticing it does not have the power it should when digging. It is an older machine but it should have more power than this. First thought was hydraulic filter, changed that along with fuel and air filters. No luck. We are running the machine at full throttle. Does this sound like a hydraulic problem or engine output? No dealer in my area to take it to. Any ideas could I get the hydraulic pressure tested? thanks very much
It sounds more like a problem with unreal expectations. What frame of reference tells you that the machine should have more power? All you can do is check the hydraulic pressures and cycle times. I don't have either specification here with me but many times you can check other machines of the same size for a general statement on cycle times. I know for instance that standard cycle time for boom up in larger excavators is around 4 seconds. If your cycle times and pressures are at factory specification there isn't a problem with the machine. Your machine is pretty old speaking in mini excavator terms. It is also a gray market machine. I haven't looked at one of those in years but as I recall they even had gear pumps.
Your relief valves may be out of whack. Can the machine lift itself off the ground? Is the engine bogging down as you are doing heavy work? A 5 tonne machine should have a fair bit of grunt but the tracks are protected by relief valves to prevent damage to the tracks.
I somewhat agree with what John has to say. Since you haven’t really given us a definitive path to go down or any conclusive evidence that it is actually under powered then all you can do is check some values and compare against the specs to determine if there actually is any problem with the machine's operation. For example, engine rpm @ high and low free idle, engine rpm @ full load, main relief pressure, secondary relief pressure, ppc pressure etc
Yeah It may be unreal expectations, but our operator who runs these things all the time says it is way underpowered compared to the bobcat 8k lb machine he normally runs, and this thing should out power a bobcat 8k lb machine. Also when trying to push the dump truck out of the ditch it would not spin the tracks, it just bogs, the machine even stalled a couple times when digging rock, is this normal? Maybe the pressure relief valves are out of whack? How can I check this? What should the hydraulic pressure be? Yes the machine will lift it self up off the ground. Where can I find a repair/shop manual for this grey maching? thanks for all the help
well if it stalled the hydraulics are fine, maybe even to much pressure. i would look at the engine.
OK, what should I look for, I guess I need a mechanic. Thanks
What would make you think a 10,000 pound machine would have more ground power than an 8,000 pound machine. They are basically all designed so they don't have enough power to spin tracks as that wears them out. Excavators are not dozers. The travel function is set up to move the machine from place to place. The phony blades they put on them are designed to fill a ditch back in and nothing more. Operators are generally not the most reliable people to believe when it comes to the production of the machine. The factory has specifications which are specific benchmarks on machine performance. In this case pressures and cycle times. Find a good mechanic. He will become your most important asset in the future. Good Luck!
most likely an engine problem. check the fuel lines, diesel filters and banjo's.(that is if the engine stallsand the machine docked for a long time?)
Yeah I am just going off what my operator said, he normally runs the 8k lb bobcat and says it would have pulled the truck out no problem, I guess I will use it for a while and see what I think. What are the Banjos? Thanks
I had a similar problem with my 1991 Hitachi EX60, It turned out to be a clog in my fuel line, I did check the banjo fitting 1st though. there were several banjo fittings and the one with the filter was hardest to get at (but not that hard). Ive also been told that in some cases they have found a rag in the bottom of the fuel tank, so I removed the tank and pressure washed it to make sure there wasnt dirt at the bottom were the fuel lie connects (and there was) . it was upon replacing the fuel line that I found the clog. Check my posts for more details. And google bajo fittings to see what they look like.
They are musical instruments played by hill billys, they may also refer to fluid fittings used in fuel systems and others. Banjo type 1 https://catalog.foothilloffroad.com/index.php?cPath=53_55&osCsid=nrlzpdwpknp Banjo type 2 YouTube - Deliverance - Banjo Duel
By 1996 most excavators have evolved enough to have enough engine grunt to work the hydraulics and open the relief valves. Hitachi are pretty good at building an excavator and I would say with some certainty that you have a lack of power from the engine. Is the engine smoky/hard to start?
it is a pc50uu2 komatsu not hitatchi, engine starts easily, a little smoke when working it hard?
What colour is the smoke? If it is black that is pretty normal but other colours are not. Not really sure why I thought the machine was a Hitachi, perhaps I was thinking of another thread:beatsme however design wise they are all pretty much the same. Has it been suggested that the strainer in the fuel tank is blocking up (if it has one). Many years ago I had trouble with a 1075 JD harvester, all season it felt like it lacked power, changed the main fuel filters, put on a new main drive belt but she still didn't feel right. Towards the end of the season I found that someone had put on an aftermarket fuel pump, right down the bottom and behind the tank (in order to pump more fuel up to the engine). This aftermarket pump had an integrated filter built in and it was all clogged up. Once that was cleaned the machine ran like a Deere should.
I think the smoke is a darker whitish color? Does that mean bad fuel?
If it has a slight bluish tint, then it means that your engine is burning its lubricating oil - i.e. bad. If it the smoke is white and it doesn't go away after a couple of minutes of running it, then it means that coolant is leaking into the block, possibly meaning a cracked block, i.e. bad news again.
First thing I would do is change the fuel filter/filters and maybe add some fuel additive. I have seen the described symptoms caused by both a clogged filter and ultra-low sulfer fuel in an older engine. Try that and let us know what happens thanks wesley
Not necessarily, these smaller Diesels may well put out lighter/grayer coloured smoke when they bog down.
Yeah, after running it today and paying attention to the smoke, it really doesn't smoke much except for just after start up and if really really bogged down. I did change all the filters, including fuel, when I first started running machine a few weeks ago, didn't notice any thing, I could do it again? Is that worth while. What about fuel pump? could this be a problem? I think it has a small cartridge type pump, looks like a inline filter but has two wires going to it? Thanks
I have a kobelco 135 SR. The #2 pump is staying engaged, it does not track well, the swing and some other functions do not work well at times, when I use another funtion the swing seems to work. While at an idle not being operated pump 1 shows 0 psi and pump 2 shows 4500 psi. When moving the thumb the psi goes to 0 but it is working fine. Any idea what is wrong with it?
We have a PC50UU-2 which smoked like a barbecue truck when we got it. Definitely "bluish tinge", and acrid - hard on the eyes to operate it with the tail upwind. Also, it was "wet stacking", producing a constant dribble of oily black sludge from the exhaust pipe. It's old, high hours, so we thought "tired engine, loose cylinders, burning oil" and we found a replacement engine block (4cyl Yanmar) with 325 hours on it, in a salvage Kohler 15kVA generator. We had to swap over almost every part beyond the head and intake manifold. This included the injector pump - the "stationary power, constant speed" governor was too "stiff" for a mobile power application. Smoking was dramatically reduced, but not eliminated, and the wet stack sludge is gone. It seems like when it is run at lower speeds, the smoking gradually gets worse as the fuel depletes, and then improves when fresh fuel is added.. but running at higher speeds, the smoke level stays constant. So.. we're attributing this to the reused, original injector pump - we think that it is allowing engine oil into the fuel. At low speeds, surplus fuel is bypassed back to the tank, so the tank fuel slowly accumulates oil. This all makes sense to us until we check the engine oil dipstick.. which has been rock steady (no apparent loss at all) for months. So, we think we're burning oil from the crankcase which enters through the injector pump.. but it's such a small amount of oil that we can't see it making a difference on the dipstick. I know this is a thread about hydraulic issues - we had those too, we found a linkage missing from the "stick position sensor" which was preventing the machine from knowing it's stick position (we think this puts the machine into a limited "safe mode" where it can move but not "perform"), and we observed that control response is proportional to battery voltage, which led us to a broken wire at the alternator - fixing that, raising the system voltage from 12 to 14.3 volts made a huge improvement. Anyway, sorry for putting a "mostly engine/fuel/smoke" post in a hydraulics thread.. but all these things are often interrelated..