Komatsu Excavator hydraulic issue

[PbBelly]

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?

 

[John C.]

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?

 

[funwithfuel]

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.

 

[PbBelly]

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!

 

[PbBelly]

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?

 

[funwithfuel]

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.

 

[PbBelly]

Thanks! I'm sure I can dig something up that will work.

 

[EEHYD]

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.

 

[EEHYD]

 

[funwithfuel]

15 minutes or 15 seconds there's a big difference between the 2

 

[EEHYD]

15 min

 

[EEHYD]

Funwithfule 13sec hot oil

 

[EEHYD]

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?

 

[John C.]

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?

 

[EEHYD]

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.

 

[EEHYD]

yes this is the initial machine

 

[funwithfuel]

15 min

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.

 

[funwithfuel]

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.

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.

 

[EEHYD]

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.

 

[EEHYD]

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?

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