I have a 2008 Komatsu PC78 u s-6 excavator that started giving me a problem It will occasionally lug the engine when using the swing function or bucket curl function. Today it stalled the engine once. Any help or suggestions would be greatly appreciated. The cost of having our Komatsu service guy out is astronomical !
Good day Suggest you begin with the engine - fuel - air - turbo - take a good note of exhaust colour when loaded. Any other machine working alongside have or had similar issues. Kind regards Uffex
The problem only occurs with certain functions of the machine. No problems with other machines using the same fuel source. I will double check fuel cap vent , fuel filter , air filter today. Thanks for the reply
Did you figure out the problem?
Not yet. I have a man looking at it now. He is so busy with farm equipment that he has been slow to get to it. The Komatsu dealer is completely useless.
How many hours are on these machines. When was the last time the hydraulic oil filter was changed, the oil changed and the suction strainer removed for inspection and cleaning. A Dash 6 is an old machine now. Grit collects in the control valves of the pump and control valves. I'm seeing plenty of age and maintenance related problems now days. Most people want a fix by turn one of two screws and changing an electrical component. When they find out a pump or engine has to come out for teardown, everything just stops and the machine gets pulled out of the way or left where it died. We are at the twenty five year mark for the first EPA regulations and going forward I expect to see plenty of dead iron covered in berry briars with trees growing through the it.
The machine I own is 2008 model with 3000 hours. The filters have been changed every 1000 hours. I did this because there is only one hydraulic filter on the machine . It also has had a complete hydraulic oil change and tank flush. The local dealer tells me I need a new pump . I had an oil analysis done which showed normal . The dealer also told 2 other fiends of mine the same thing about their machines even though they did no testing on them .As a result I have no confidence in them other than to supply parts at exorbitant prices .
Ya, I think I agree with you in not trusting the dealer at this point. The reason I asked the questions above is that number of hours is pretty light for being thirteen years old and I think the models were into the Dash 7 group by that time. Doesn't matter at this point. Do you know how to get into the diagnostic package in the monitor panel? Have you had any alarms and fault codes show up?
I have had no alarms and was told by the Komatsu tech that there was no way to pull up trouble codes on these machines. This was contrary to what i had been told about them He also told me that he had checked pressures on the pump. I do not beleive this to be true as he wasw only at the location for about 20 minutes and used no gauges of any sort. The pump on the machine is very strong and responsive until it starts choking the engine down which is very intermitant
Can you post a photo of the monitor panel in your machine?
If the hydraulics are pulling the motor down, the exhaust will go black. If the exhaust doesn't go black, it's a fuel supply issue. I'd start by examining the supply side, including the tank outlet, looking for a screen. My bigger, older, komatsus have a screen in the tank outlet. If no screen is there, examine the water separator, including full removal and examining the inlet path for partial blockage. I dont have enough fingers and toes to count how many times I've had fuel restrictions before the lift pump on my smaller machines, Komatsu, Yanmar, Takeuchi, Kubota, Kobelco. The Kobelco had cellophane in the banjo fitting screen at the water separator @ 240 hours. The Takeuchi CTLs would collect debris in the tank outlet elbow. And the Kubota CTLs would plug the inlet elbow at the water separator. And my Cat SSL would plug the inlet path at the separator head/ priming pump.
It will be next week before I can get to the machine. I have checked the fuel system thoroughly, even replacing the lift pimp. It`s the kind of problem where you do something and think it is fixed only to have it pop up again ! There was a comment about the hours on the machine. The hours are low because I have 5 pieces of equipment and run them all pretty much myself. Also I turned 71 in February and have slowed down just a tick.
I have the same machine which is a 2006 with 3,500 hours.It also has the same issue.I was wondering if you have any luck finding out the problem?
So far I have not. I have two friends with the same machine and having the same problem. Our dealer H&E Equipment tells us the pumps go bad at approximately 3000 hours. I had a oil analysis done and it showed normal. Because of this I do not think the pump is bad. It is hard to believe that Komatsu would allow a product to be on the market with that poor of a life span !
When did H&E become a Komatsu dealer? No new machine dealer would ever say something like that. First off it isn’t true to my knowledge and second, it shows they don’t know how to fix them.
It takes 5k hours for the stroke piston to start sticking in the main hydraulic pump in 544J and WA270-7 machines, but, not all of them. And 5k hours before the slipper shoes self destruct in one pump on a 345CL. Other than that, I've never had issues like you're describing, especially at that low of an hour meter reading. Again, when the motor bogs, is the exhaust darker than normal?
The windows are tinted so it`s hard to tell. The H&E tech came and looked at my machine and a friends at the same time and told us the pumps went bad at 3000 hours. He also charged for testing pressures , which I don`t think he could have done because he was only there for 30 to 45 minutes and used no gauges. This was for two machines . Both machines were at the same location in order to try and save on the service call charge. I have had CAT an CASE machines in the past and have never had problems such as I am having with this machine and service.
The exhaust is darker than normal on my machine when the issue occurs.
I have replaced hydraulic pumps on 2 of these machines due to the same issue. Local pump shop advised its a bad design with it not backing off properly at full demand. New pump-no issues
so would adjusting the pressure compensator to a lower max psi or the swash plate endstop adjustment give the pumps more life?
I tried adjusting everything to make it stop stalling the engine with no luck
Did the “Independent” shop provide a failed part or at least a photo of what was wrong? Do you have any info of updates on the new pumps? I’m not trying to defend Komatsu if they built a dud. I would like some sort of documentation that can be used for the future.
Is it possible to rebuild the pump or must it be replaced. I would hate to replace the pump only to have it fail again !
Yes it is possible to rebuild the hydraulic pump. The problem with rebuilding is setting the output curve to the engine and the machine. Nearly none of the independent repair shops have the equipment or the knowledge to be able to do it right.
Could you please elaborate on this or provide a link to an explanation. Is this an adjustment that is made to the internals of the pump (in this case a variable displacement axial piston pump with load sense I assume) or the setting of the flow and pressure compensation valves / swash plate angle stops, etc.? I haven't heard this consideration before and assumed that you simply replaced internals, lapped useable worn parts, and swapped it into the machine. Thanks
Repair shops can't set the load curve because they don't have a way to set the differential pressure on the load sensing circuit. The pumps are also computer controlled and the shops can't set to the computer that is still installed in the machine. What people don't understand is that the pumps and control valves are a set in that they have to be adjusted to each other. What those shops do is what you have stated, lap the valve plate to the barrel, install new bearings and seals. They may put the pump on a stand and run a pressure test and then write down a case drain flow trying to indicate pump efficiency. Case drain on a pump, especially a Komatsu pump, doesn't mean a thing when many now days have a pump in the suction port pushing fluid through and out the case drain. They do not adjust the stops and never touch a flow control valve other than removing the cartridge from the pump casing. If they are lucky the adjustments are still close enough that no one notices a change in performance or heat. Even if the customer does notice a difference, the pump shops will tell the owner to adjust a screw at most. Many look for a reason to find the customer at fault when they installed the pump. I made decent money some years ago going out and adjusting pumps to the machines after an expensive "REBUILD" done by an after market shop that purported to be "Experts." I still get calls for and have done a couple even this year.
If I get the gist it's that you have to reset the LS margin pressure while the machine is operating because the DCV(s) boil down to an orifice size that is machine specific?
Margin isn’t that big a deal. You just have to have a difference between pump output pressure and load sense pressure on the closed center load sensing system. You also have to set TVC on some pumps to match each pump. On others you have to adjust LS output to balance the pumps. It all depends on the model and vintage of the machine and pumps.
Thanks
Sorry I have no documentation or specifics the failure. It wasn't a pump I had sent in. Just a phone call to the rebuild shop. I was following up with a different unit that had been repaired by someone else with the same failure, trying to figure out what I was going to do with the unit I had