Hello For a few years now I and several mechanics have been trying to get to the bottom of this issue on my excavator. It began as a load on the hydraulics you can hear when you start the machine. Starts and sounds normal, then the hyd system loads up and you can hear it put a load on the engine. For a period of time, surging the right track would return the system to normal load, only to return in 3 seconds. It also used to have worse problems in fall and winter but went all summer with no problem. Now it has manifested into a problem of mayor power loss, the machine will stall/deadhead at the with most functions tracks and stick seem to be affected the most. Replaced pilot pump, rebuilt pilot valve, both full of debris and not functioning properly. To my amazement this did not solve the issue. Replaced 2 leaking cylinders that may have discharged the debris into the system also. Just ordered dp sensor, angle sensor, high speed solenoid, but we are guessing. It is an asian machine and biggest problem is I can't find specs for it or plug in to it for diagnotsitcs because it is grey market. Another off symptom I'v noticed is that when machine sits on a steep incline while working it works correctly for a period of time. Yesterday I was letting it idle after getting pilot pump and everything back on and the engine idle excellerated on it's own with the hydraulics safety lever still in off position. It did it again so I climbed in the cab and the green lights on the dash were dim and flickering. Alternator has been tested. I could really use some advice, can't replace the machine just yet got to get back to work.
Welcome to HEF natemarine ! This could be the entire problem. What kind of debris? Did you take pictures to share? Did you check the suction screen in the hydraulic reservoir? Drain reservoir and inspect the bottom for debris? Cut open the hydraulic filter and inspect for debris as well as the pilot filter. If the debris got spread through the system then it could be causing various functions, solenoid valves, etc to operate intermittently. Next time your instrument lights act up, disconnect the blue/yellow wire from the alternator and ground it to see if that resolves the light issue. If not then connect the wire back to the alternator.
Thank you... I dont have any pictures unfortunately. It was pieces of plastic in the pilot pump probably from the bucket and boom cylinders we were thinking but I don't really know where it came from....Bucket cylinder was in bad shape and I ran it that way for a bit not knowing any better. The pilot valve had clogged ports and had alot of buildup inside. The guy who rebuilt it was a pro I was not the one. The filters were visually inspected, but not cut open, reservoir not drained. We are going to get into the cab and inspect all wiring and harnesses etc. tomorrow.
ok sorry I'm new at this forum I wasnt sure if I had to quote you in my reply to send an alert
Have cheked all wiring and fuses and harnesses. Replacing the dp sensor high speed solenoid and angle sensor today, but I'd like to know what the next step should be....
Just replacing those parts will mean nothing unless they are properly adjusted. If not properly adjusted they could make the problem worse. Is there debris in the tank? If your hydraulics are under load at start up then swap the solenoid assemblies on top of the pump to see if your hydraulics change.
When we swapped the solenoids everything sounded right.....the engine engaged quickly when touching the levers, instead of slowly revving up and having a load....it fixed the problem by sound but all the functions were super slow ..... does this tell us something? Also any advice on adjusting? I only had one new one to replace. They are the same solenoid correct?
Also when I bought this machine the line from the pilot pump used to pulse, I am reading here that that is normal, my machine no longer does this.... I have no manual but I just ordered a hard copy I hope its the right thing it is a technical shop manual for hitachi 120-3 it supposed to be here next week but any advice you could give to keep us going would help
Id be happy to talk on the phone if its easier/faster my #443-677-2324 I text too.....Nate
Yes the 2 solenoids are the same. If you had aggressive hydraulics before swapping and then had weak hydraulics after swapping then one of the solenoid valve assemblies are defective. I believe you mentioned aggressive hydraulics in your original post. Did you have aggressive hydraulics before the swap?
I don't know if I'd call them aggressive but fast like normal, maybe a little faster than normal
to clarify, when they were switched the functions were clearly different, all of the hydraulic problems seemed to go away by ear. but functions were slow. When switched back it went back to the same old problems. Does this mean one was bad? or both? I had one new one we used to check them. I'ts still on there.
Take a look behind the seat and the computer should have a light on it, I forget now how the light works but if memory serves me right it has to do with power to ecm, there are a couple fuses in there, 1 amp DO NOT PUT ANY OTHER FUSE IN ITS PLACE. How Fast the functions run, or their touchyness/aggressiveness can be adjusted. I purchases a tool to read codes on hitatchi at one point for similar issues. Debris in the pilot pump...... The pilot pump shifts the swashplate, maybe corelated, there is a pilot filter to look at. The service manual will tell you to check the arm atatched to the sensor on the pump is attatched.
If old problems were stalling when activating a function, then yes there would be a defective solenoid valve.
1. My main sympstoms are dead heading and stalling the engine when, tracking, lifting weight aggressively, or extending the boom stick or bucket cylinders all of the way. It coincides with extra vibration, black smoke when it labors, hydraulics bleed off, when sitting stationary. I can hear a load on the hydraulics on cold start after 3 sec. 2. I would buy that tool if I knew it would work but this is a grey market machine. 3. Also the pulsing I used to hear in the pilot pump doesnt exist any more I hear this is not right 4. I did a test I see alot of people recommending on here. Switched the solenoid valves on main pump and there was a change. I hear this indicates a bad solenoid. One was replaced with a new one, I'm unsure if this is the issue but about to order another new to be sure they are both operational. I will look for a light, to clarify you mean behind the seat on the computer itself not the instrument panel corrrect?
my apologies I just got this laptop and can't figure out how to cut and paste yet lol further details above but basically the original issues were it would stall when a load was put on it, black smoke, and stall if you lift too heavy of weight or track without pausing, or extend any of the cylinders on the boom all of the way I didn't have out of the norm fast movements or anything
also I did check all the fuses.... and...they were all fine assuming they were all in the correct spot I have a diagram I'm going to confirm. I took the bottom plate off and cleaned the two main grounds but they were probably fine. The two computers in the back have an active red flashing light on each one.
Yes these can be head scratchers, sounds like your pumps arent shifting, which: A) The internals of the pump arent shifting (mechanical issue) B) The Sensing system is not picking up that it needs to shift, Dp sensor, Angle sensor. C) The the Control side is not shifting the pump, Pump Solenoids The Dp sensor is expensive from Deere, however I have bought aftermarked DP sensors and they where junk.
Did you replace all the parts with the original hitachi parts? Specialy the pump solenoids? Did you set the angle sensor correctly? China made parts wont solve the problem on electrical side. This machine is very complicated and fragile to handle. Did you check also the pilot pump pressure reading? Is the pvc computer working properly? Did you check the wiring continuity for all the sensors and solenoids?
Then maybe the wrong solenoid was replaced?
ll be honest, from the symptoms I'm starting to think I had one bad solenoid at first. Then I had a muffler problem that was causing over heating. The temp got up high a few times but when the buzzer came on I always shut down operation to let it cool. Im thinking during this time the other solenoid may have started to malfunction as well. Is it possible to have two of them malfunctioning? Also I have to ask, why are the aftermarket replacement parts no good? Dealership wants way way too much money for original parts. After all this isn't an american hitachi. The part numbers matched.... everything seemed exactly the same. Is there any particular reason they won't work? Besides the dealerships upcharging their brand names for a ridiculous profit, is there really a difference?
we tried many combinations with the new solenoid changing location and then switching wires back and forth. No matter what combination we used we either got slow functions with no load on hydraulics, everything sounded right and normal for once. When switched the functions turn fast and jerky, and the load on the hydraulics returns. The fast and jerky didn't start until we installed the new solenoid, it definately caused a change. So i am assuming the one we replaced was bad and it seems like the other may still be messed up, another aftermarket on the way....
I'm hearing mixed reviews.... is there a problem with after market parts? Dealership wants way too much money for them, what is the difference? the dealer said its the same but it affects warranties, I dont have a warranty lol. pilot pressure pump was just replaced I'm assuming the pressure is good. Have checked all the wiring and harnesses for frayed wires or wear but not for continuity. It has been a problem to get shop manuals and specs because it is gray market machine. I just found a guy with the john deere 490 e program on his computer but I'm thinking about ordering dr. zx (mine is ex) Did not adjust angle sensor tried to put it in exact position as the other (do this by ear? using laptop? please advise...) Both computers (on top of eachother behind seat) had flashing red lights when I checked beyond this I don't know if pvc is functioning properly I have tried to hired heavy equipment repair companies to fix it but they can't ever figure it out
My Experience with aftermarked sensors can be summed up by this box, notice the shiny DP Sensors, and the shiny angle sensors, all junk the problem is you will chase your tail after you put a new after market sensor in. I believe the new DP sensor is $1000 from Deere. Setting the Angle Sensor take a special harness The scanner is nothing special, basically a code reader made out of a PDA, those machines do not have super diagnostic capability, probably a 94 machine, think of the diagnostic capability in Cars in 94, Ford was probably still using the analog analizer to count out codes. To bad I was just in Maryland, stayed on the patomic river in harpers ferry if memory serves me right.
Look down along side the right side of the seat towards the back of the cab. You will find a square 4 terminal plug, flat terminals. It's just hanging there and sometimes is a bit hard to find.
we will be tempted to buy the replacement because of the price difference but it is always a waste of money either. I have a lot of that china solenoids. then I learned my lesson after a lot of money wasted. continuity checks for the wiring is a MUST to do. working parts is useless without doing this. dr zx will accelerate this task. you can see all the sensors reading on dr zx. and can start tracing for the sensor lines that is not have reading. for the actuators(solenoids) needs line voltage check. pump solenoid is ground controlled by the computer so live 24v is always constant via a relay which is also controlled by the computer. use the genuine parts specially the 2 pump solenoid. computer power blinking does not mean its working. quick parts problem elimination is by installing the suspected bad parts to a normal working machine but we don't have all the resources to do that. angle sensor should be set up properly with dr. zx or manually by a tester.
I know when the light is not blinking it is a problem, had a customer working on his own machine short out the computer.
Hope that is helpful. It's EX120-3 full Technical manual. http://www.mediafire.com/file/o8dxek1yvr4h5tm/EX120-3_T135E-00_Technical_Manual.pdf/file
The 490E program should work fine.
Update: I was told this wasn't a big deal but thought I would run it by you guys. When searching for answers I found the hyd temp sensor on the bottom of the hyd tank was definetly messed up. The wire broken and sensor wire end, sensor may be ok. A friend / diesel mechanic said no big deal just was hyd temp sending unit.... but is there more to it?
To be honest with you, I rarely see a hyd. temp sensor working on the older machines. Should not cause a problem.
lachau - do you have a link for the ex120-5 manual? Or is the -3 similar enough to use?
Update I have additionally replaced the pressure sensor with no change. Still waiting on second solenoid to be delivered. I have hard copies of the technical and shop manuals I have dr. zx software and data link wire with usb for laptop on the way. One of the kind members on this site connected me with the windr program and the technical manual. I don't have a laptop but I do have a brand new chromebook they say the new dr zx software is compatable I'm not sure. Are these programs the same? Is one better than the other? I'm thinking/hoping between all these we will find a true diagnosis. In all my research here it seems to me like multiple things may be malfunctioning. Anyone have any advice on which is better?
Setting the pump angle sensor with a multimeter is important, I don't think dr. Zx will accomplish that task, you need special harness, might be able to make one. See my earlier post for the harness, also you notice in my picture an angle sensor that did not pass setup and was junk, causing major operational issues.
It may be same like this.
WinDr became MPDr and that is the dealer level software.
Wow, we are getting serious now, never seen it in color before, I always had to deal with this problem with the manual open on the back of a service truck with the wind blowing or the mesquitos buzzing in your ear, you think i am joking but i bet the manual has mosquitos in the pages on the shelf. Have seen angle sensors aftermarket out of the box not pass this range test. There was a hydraulic kit out there that got rid of all the electrical stuff on this machine and made it a full hydraulic controlled machine.
dieseldog, have you ever seen one of those kits actually work? I don't think I have heard of anyone who installed one say it made the machine run like it was supposed to.
That 's called conversion kit. The first one which I saw in 1999. Let me show you the it's components. After that, I had drawn the principle.
Of course, the modified job may not work as well as the original. I have actually been doing that since 1999 with EX200-2 excavator.
I have not seen one on a machine, but considered buying one when I was pulling my hair out with a 120-2/3. I have one customer that has had 5 of these Hitatchi machines and each one has had its issues, in the end got some what proficient with these machines. I faought with parts that new were junk and that threw me for a loop, DP Sensor from Deere is like 1200 Bucks, overboard if you ask me. LACHAU, does the 200-2 normally run without electronics or is that something you came up with.
I have one question When field testing the solenoid valves on top of the main pump. I have read and have been told to switch wires to them and see what happens. I'm not sure what's supposed to happen,or what this tells me. Please inform. When I did it, the load came off the hydraulics and the rpms returned to normal. The functions moved very slow. When switched back they machine returned to the same malfunction. Its the first time in a long time I've heard the hydraulics running "stress free" (weak hydraulics that will stall at full displacement) Is there a way to test the solenoids with a multimeter? Still waiting on dr. zx data link cable, trying to use this time produtively
If you have TM1504, go to section 9025-15. Look for Introduction to Flow Charts and go to the first chart. The first line deals with engine stalls easily under load. Check to see if you have 24 V to both displacement solenoids with the key on engine off. Each solenoid has it's own relay that supplies them with 24 V. Yes. Spec is 15.5 (+/-) 5 Ohms The reason for change when swapping the wires is that one of the wires is supplying the voltage to destroke the pump and the other one is for placing the pump into stroke, so if you put the "destroke" wire onto the "in-stroke" solenoid then when the machine has no levers activated the PVC is sending a signal to destroke (activating the in-stroke valve) and your machine is under load at start up. You need to swap the entire pump displacement solenoid valve assemblies, not the wires to see if one of your displacement solenoids are defective.
Last time in Vietnam, we also had a headache with EX DASH 2 electronic parts, so sometimes we had to install the converter as a temporary solution. The electronic parts of EX-2 are now cheap in Vietnam, so we try to fix it as the original. If you are going to install the converter for EX-2, it will take you a lot of time for adjustment. Few pictures of EX200-2 on test bench for your reference.
Ok guys thank you all for your assistance. I will keep a long story short but here is what the 3 problems I discovered were. 1.angle sensor went bad first a year or so ago 2.(bad solenoid valve) muffler developed a hole and blew hot air on hyd tank and pumps causing additional overheating during that time one of the solenoid valves on the main pump went bad also 3.(reversed wires) at some point someone I had look at the machine a while back reversed the wires on the two solenoid valves trying to figure out what was wrong when it was the angle sensor The good thing is now I have the shop manuals and technical manuals and the dr ex diagnostic equipment for when it happens again. Thanks again, machine is sounding great, and lifting heavy weight easily again. Time to get to work!
Good job Nate! Thanks for posting the results. Happy digging .
Congratulations, the results sound about par for the course with these Hitachi's. A lot of the time I get calls from people of what is wrong that causes such and such, and alot of the time it is not as cut and dry as change sensor A, I have a proceedure for trouble shooting that works for me, and I have been successfull with however I can't write it down because it is more of a personality than a proceedure, some people would like you to get in and out in an hour, have an answer and machine fixed for $50, thats just not how it works, sometimes diagnostics is verifying systems are good in order to rule them out, like your wiring being reversed, seems simple to verify wiring, and 9 times out of 10 would be correct, but look you caught the 1 out of 10 that needed it. Sounds like you had the diagnosis part handled, we just provided encouragement!
I've been following this one and like others above it's nice when the person who started the thread actually comes back with the information regarding what the final fix (or fixes) was. Kudos.
Hi guys hope your all still following. We got back to work yesterday demolition on a pier. I'v noticed two things. The hydraulic power is stronger lifting weight easier and higher than before with no black smoke or load on the engine or stalling. When I hold the controls it functions normally over relief. What I've noticed is a lack of lift power on the boom and stick. Id say it's at about 75% of full power. It used to pull alot harder. I don't dig that often but my guess is it would affect that too. You all warned me about using after market parts. I'm not sure how I would know if that was the issue, and I'd hate to start buying genuine parts just to find out. I have set the voltage correctly on dp and angle sensors... but I don't know how I would tell. The aftermarket parts I put on were dp sensor angle sensor pressure sensor and pump control solenoid valves. I can't find a troubleshoot for weak functioning hydraulics with no stalling etc. I am still trying to install drzx and windr but unsucessful linking the machine so far. In a strange twist at the end of the day I shut the machine down normally, after shut down for 5 seconds the engine oil pressure alarm started going off..... not while machine was on....only when off 1. How do I tell if the aftermarket parts I used are good or faulty. The voltage checks out so far but I don't know if that's everything. 2. What would cause everything to seem right but just not have the power I should have. 3. What's up with that oil pressure alarm? 4. Machine will still rev up on it's own with no one in cab. As if someone had touched the controls. thanks guys, it seems like more that 3 problems....still better than it was but not done
What do you mean??? Performance of BOOM and STICK are SLOW or WEAK?? If their performance are weak, you should measure main pump pressure to check.
just weak, I think theyre moving pretty normal speed
All right, Have you check How is main pump pressure??
They should be as follow. Attention: Don't trust Dr.ZX completely, use a pressure gauge to measure directly at the main pump.
Naremarine did you ever get that machine going properly been reading all of ye posts there and they are really helpful i have a hitachi ex120-3 it go under load aswell not so much to stall it kinda half load but i still can work away but its get hot after a hour sometimes the tracks won't move but if I mess around with the joy sticks it will track on again anyone here have the same problem any help appreciated Thanks
natemarine was last seen June 2020 ,likely won’t hear from him. @john tom , suggest to start your own thread with problem details and what you may have done to try and fix the issue(s).