My cousin is running a Komatsu PC138 USLC-2EO excavator ser# 2078 Product ID # KMTPCO44T044T01002078. He bought it 10+ years ago with 1,700 hours on it. From day one it has had a problem not steering when tramming once the machine is thoroughly warmed up. It works fine for the first couple of hours on a warm day and may not misbehave at all on a winter day. It trams fine, although it does seem slower on an incline once warm, but the only way he can turn the machine is to help things along with the boom. Sometimes he is able to steer it somewhat when tramming downhill. Apparently there is a separate pump for each side's drive motor, but both sides misbehave equally. Over the years he has spent over $9,000 with various Komatsu service departments trying to get to the bottom of this [pump rebuild, hyd. cooler repairs/mods etc.], and nothing has been successful. He thought the most recent visit had cured the problem. A Komatsu tech adjusted some of the pressure settings that were "low", and it seemed to have cured the problem for a few hours, but now it is right back to behaving as usual. Fortunately, this machine is typically used intermittently enough (load a truck and cool off while the truck was gone unloading) that it isn't an issue, so he's has lived with it. (it is up to 5,600 hours now). But there is some more constant work coming up in the future and he would like to get to the bottom of the problem. Several of the techs that have worked on it say they've never seen another one like this, but they also admit that they typically work on much larger excavators. The last conversation he had with the most recent Komatsu dealer he's been talking to ended with the suggestion that he try replacing the hydraulic oil with 30W motor oil. He doesn't like that idea. Supposedly this machine was imported from the UK. Were their spec models different from those destined for the US? Has anyone had similar issues with one of these?
My book shows it as a 2007 model machine. If you can get a photo of the pump so I can tell if it has the CLSS hydraulic system or the OLSS system. Do you know if there are any fault codes and does the owner know how to access the diagnostics menu?
Just to add on John's comment, if he can access the service screen, watch hydro pressure while deadheading functions. Document each pressure, pin the tracks , measure those pressures as well. Do this cold, then hot. Before anything, measure track sag left and right against spec's. If tracks are too tight, it won't behave properly. I can't believe dealer techs would miss this, it's the first, simplest thing to do. But I'm not them, so we can't assume anything. Clean the tracks. Paint a pad and raise it off the ground. Measure the time it takes for 3 revolutions from a running start in high range. Do this on both sides, cold, then hot. With this info, we might be able to better help. Right now if forced to guess, I'd say turning joint. But its just that, a guess. Need numbers.
I'll talk to him. He has never mentioned nay fault codes, but I seriously doubt he has the ability to access them-he still uses a flip phone. I'll go get a picture of the the pump(s) and time the track revolutions. It may be a day or two before we can coordinate a time to get together. Thanks so much for your input!
When you say "pin the tracks" I assume there's a ready-made spot to do this? Is there a pin stored somewhere on the machine? If not, about how big of a pin/bar do I need to take with me?
70 maybe 80mm you stick the pin between the sprocket tooth and track frame. You track fwd til the pin is "jammed" in between. It is now that you read relief pressure. Then move the pin between the bottom tooth and frame walking backwards til pin is jammed. Now you get rev relief psi. Both sides, fwd and back, high, med and low range depending on how many travel speeds you have Typically , a bucket pin is the right diameter.
Thanks! I'm sure I can dig something up that will work.
This is Jesse. I currently have the excavator and have performed the pressure test at 70 degrees. The pump is making 4600 psi and after 15 minutes of dead head against the auxiliary function the pressure drops to 2800 psi. The Pilot pressure stays consistent. All functions are weak and slow.
15 minutes or 15 seconds there's a big difference between the 2
15 min
Funwithfule 13sec hot oil
The pump in the photo is for a CLSS system. I haven't seen that type of outlet connection piping on any of the domestic excavators. There are two fittings on the right side of the photo and I can see where paint has been knocked off the flats on the front cartridge. The issue of running the pump over relief brings up a couple of questions. First why would you hold any pump over relief for that amount of time? The second question I ask is what is supposed to be wrong with this machine? Is this the machine the initial poster is talking about?
i did this to build oil temp, this was at 2400 psi. it was not full system pressure. in the book it talks about testing the ls differential psi i did this and its way off the charts. ls port is 2300 psi under full bypass and work port was at 4600 psi.
yes this is the initial machine
Why? For future reference, curl bucket over relief and swing arm in and out til your oil temperature comes up. Running a pump over relief like that is, well it isn't good. You could also lock the house and swing against the brake while exercising the arm or boom. This allows oil to circulate and provide lubrication. What you are doing is beating the tar out of a very small amount of oil and it is probably breaking down. Plus your doing everything you can to ruin your main or the port relief since your option is usually lower than main. Let's not do that anymore. Sorry I didn't respond sooner, I was out of cell service.
I would speculate that the main is getting weak. How are you producing 4600 with a 2300 unload pressure. It can only be as high as the strongest circuit. Unless, you have 2 pump flow going to your option. What about testing track speed as previously suggested? What are your pump pressures for bucket, arm, boom, pinned travel ? These are values we can use. Please test all functions @ full throttle, please write down each value for each pump for each function @ full throttle end of stroke. No more than 1 or 2 seconds to achieve a reading. I might be new to Komatsu, but not excavators. What we're asking for is kinda universal towards getting a handle on the health of the machine.
I am sorry but I don’t need your advice on testing, you are obviously not very experienced with this Or exactly what I am doing. Plz read all of the post if you would like to comment on this post. Also go back and read what you have already, because you have mixed that up also.
Sorry for the confusion it was not the equipment Relief valve this was done on a flow meter on the auxiliary ports. I set it at 2800 psi and it took that long to get the oil up to temp. That’s why I waited 15 mins
OK ,so I understand this correctly, You put a flow meter in the system and then cranked the valve on the flow meter in to get 2800PSI on the gauge and ran things that way until system was warm. Is that correct? So everyone else knows a little more about the system I'll put some more information here. The system is CLSS which mean closed center load sensing system. Basically the pump output is set to be about 300 PSI higher than the oil leaving the control valve going to a function. Once the pump pressure and the load sensing (LS) pressure are the same the pump is at minimum stroke. There is no such thing as "Standby Pressure" in the Komatsu systems. In essence in normal operating mode the main relief very rarely ever opens. The only time it will open is when the power up function is operated. There is a button on the left control handle that when pushed will max out the flow of the pump and raise main relief pressure to a higher point. When you put the machine in travel you also get the higher flow and raised main relief pressure. The other way to apply this is to set the swing brake and operate the swing in either direction. Komatsu actually recommends setting the swing brake and operating the swing for several minutes in the morning before putting the machine to work, just to warm up the oil. Back to the current issue. You only have one pump running the whole machine in this size range. I don't know where you are testing LS pressure from but that reading you are stating is wrong. If there was that much difference between LS pressure and pump discharge pressure the engine would be dragged to a complete stop. What your problem sounds to me like is that the TVC pressure has drifted down some. It is not a pressure that you can plug a gauge into and read. If you look at the photo you posted and see the fitting I spoke of with the paint knocked off it. Behind that fitting is a bulbous looking connection, basically a banjo type bolt. That is where you adjust TVC at on this particular pump. Loosen the nut holding the bulb tight just enough that you can turn the fitting and hose attached to it. Underneath that is a lock nut holding what is actually a bolt adjuster that is the center part going through the bulb. Mark where the bolt is at currently so you can go back if it doesn't work when you adjust it. Going in will increase pump output. I usually worked them in half flat increments because it doesn't take much to start dragging down the engine. You don't want to draw the engine down much more than 150 RPM under full load. I usually adjusted the bolt with the engine shut down and then tested operation. I have done them when running but sometimes it will blow one of the O rings in the banjo fitting. Good Luck and let us know what you find.
The book called it something else I tested the LS on the top of the pump where I have the gauge port as directed by the book then got the system pressure from the top of the valve just off center. Both fittings are 12x1.25 and not that I am saying your wrong at all I just followed the book on testing the Differential on the LS and it’s way off I don’t get how the LS can be lower than the working pressure? Also I would like to come up with a way to test the pump with the flow meter can I turn this pump in to a pressure comp system? Also I had 13 seconds on 3 revolutions of the track with hot oil.
I think most all of the pump adjusting stuff was written so that it couldn't be understood and the locations of the gauge ports had to be experimented with. After messing with trying to figure out LS pressure for a couple of years I got where I didn't care what it was as long as I had good feel on the controls. That adjustment I told you of sets pump absorption torque. The travel issue originally described indicates to me that the output of the pump has backed of slightly and is de-stroking too soon.
Ok I will try it
It only losses power after its hot
so i have tested the pump it is in perfect working order, i did find out that i have 13 gpm going from the pump to the valve at 550 psi. this is with no functions being used just starting up. as i heat up the oil the pressure port and suction become hot, the only other thing that gets hot, is the top end plate on the valve. where could 13 gpm be going?
That 13 gallons is minimum flow from the pump. It fills the valve and load sense piping and goes through the cooler or directly back to the tank. I don't remember for sure exactly which way for sure.
help! how to disable lock engine function? komatsu pc200-8N1 it shows error code D19JKZ and we've already checked all harness and fuses. they're all okay. the engine won't start but cranking, just wont continue
Do you know how to get into the diagnostics? Have you checked the essentials first? Air filter, fuel water separator and fuel filters. I don't have a complete list of Dash 8 codes so can't help you there. Someone should be able to help.
yes. checked all essentials and even calibrated the injectors yet the same code keeps appearing on the monitor. D19JKZ