I have a 2001 Hitachi EX 120-5. Recently it has developed a problem with the throttle control and ignition switch. When I start the engine with the key switch the engine revs up then dies. I restart the engine and it will run normally. The auto idle will operate until the engine warms up then it will not return the engine idle as a low as it should. When I attempt to kill the engine by turning the key to the off position it goes to a rough very low idle. Then when I turn the key to the run position the engine shuts off. Does this sound like a problem with the ignition switch, the throttle control motor or some other electrical problem? Another unrelated problem is when the AC is running and the machine is under heavy digging conditions the engine heats up. I must stop work and turn off the AC for a few minutes and let the engine idle until the temperature drops and the light goes off. I have heard somewhere that using anything other than Hitachi hydraulic oil will cause the overheating problem. I have been using John Deere Hy-guard oil. anyone know anything about this? Thank you in advance.
Hard to say on the engine rev/start/stop stuff.... maybe computer related.... bad grounds or something that might mess with the computer??? could be the key switch it's old enough... not sure how the rough idle and speeds would be from that though??? how many hours? and any other info you can post up may help someone that knows more on this than I do as for the a/c thing just a far out guess but make sure the your radiator and condenser are not full of dirt/mud/dust it happens a lot on excavators around here and severely limits the efficiency of the engine cooling system... so much so that when you do use a/c the extra heat from the a/c condenser is enough to push the engine cooling system into the red.... anyways just one possibility of what might be happening and I am not too familiar with the -5's so not sure how they have all the coils stacked in there.
Thank you for your input. The machine has about 5300 hours. John Deere dealer worked on excavator in 2018 in an attempt to improve the cooling system but to no avail. still overheats. I'll check the wiring as best I can for loose connections. More than that I will be over my head.
When it's hot out here 75-80+ we have to clean the radiators twice a week in our 120-2 or it get a bit warm... it's a might older than yours but probably similar cooling stack I'd bet... there's usually screens you need to pull also in front(airflow) of the radiators. Sometimes the shrouds get busted up and aren't as efficient as normal, have also read of machines with hydraulic issues that do cause lots of heat to be generated in the hydraulic system and that in turn goes to the hydraulic cooler which *could* affect the engine cooling... there are just lots of variables involved including how hot it actually gets in degrees?
Ok thanks. Going to freeze here this week so don't have to worry about overheating until spring.
U HAVE TO run a throttle calibration.. a "learn".. When u turn the key ON.. do u wait a minute.. or do u try to start it like a car.. U have to wait until it runs thru its "learn" before u can start it.. It 's outta calibration.. it runs rough because it cant pull the lever to shut-off.. but its trying. & when u turn the key to RUN.. it cycles its throw & goes to shut-off in the cycle. Have u WATCHED IT.?? U gotta know how it works before u can fix it..
Your machine may need to perform "ENGINE LEARNING CONTROL".
My 120-5 ran fairly warm like yours before I blew out the radiator really good. First I made an attachment for my air nozzle, so I could insert it between the condenser and radiator and blow out the radiator core. Then slid a piece of cardboard down between the radiator and condenser so the attachement wouldn't hit the cooling fins on the condenser as a I moved the attachment around in there. It amazed me how much dirt came out. While it sill runs a bit warm, its no where near what it use to be like. When it hits 90f+, I still have to open the hood up though.
Pump Guy and Lachau, Thank you for the information. I'll try your suggestions. I'm not by any means a mechanic and know just enough to get myself in over my head. Shoe49
Last fall I installed a master switch on the battery ground cable. Could shutting off the power have anything to do with getting things out of sync?
pp13bnos I have tried blowing out the radiator with air but it is as you said difficult to get into. On the hot days I have been running with the side doors open with vice grips to keep them open. That helps some but not enough.
Hey Guys I did the the engine learning procedure as describe and now the ignition switch does kill the engine when I turn it to the off position. However, when I start the engine it goes to full throttle and by turning the throttle control knob I can get only a slight decrease in RPMs. When the AI is activated the engine decelerates only slightly also. Am I looking at an electrical problem?
Sorry for unclear information last time!! Have you performed same as the image below yet??
Ok thank you Lachau Ill try it all today.
When I've seen the problem you are describing with the throttle control, it usually had something to do with the throttle cable beginning to fail. Usually they get sticky and won't move past a certain point easily. This causes the problems with the computer knowing where the throttle stops are and creating the mis-reads by the computer.
John C I'm thinking you may be right about the throttle cable. Today I loosened the clamp on the stepping motor and pushed the lever to an idle position and the throttle control would cause the engine to idle ok but would not return to full throttle. Then when I restart the engine it goes to full throttle and will not idle down. I think I will order a new throttle cable before replacing the stepping motor. Although the throttle motor makes quite a grinding sound when I turn the ignition to the on position.
The grinding you're hearing may just be the stepper stalling because of too much torque to overcome a bad cable???
Ordered a new cable today...should be here in about three weeks.
To add to my earlier post... if there is grinding you should be able to feel it with the power off and moving the cable/stepper back n' forth a few times.
Some more causes for you reference. Good luck.
Thank you Lachau. My new throttle cable should be delivered by the end of this month. I strongly suspect the root of my problem is a seized throttle cable because the muffler has developed a hole in the bottom allowing the hot exhaust to blow directly onto the cable. I'm also installing a new muffler.
Thanks to all who offered assistance with my EX120-5 throttle control problem. I ordered a new aftermarket stepping motor from Mottrol and installed it today. After performing the engine learning procedure I finally have positive results. The throttle control is working again.
shoe49....I am struggling with similar issues with my throttle control, did you have any luck with the cable or did you determine it was the stepping motor? I have a 100-5 and I'm sure it has the same stepping motor. Do you have a link and or part number for that aftermarket motor?
bflobil, This shoe 49 under a new name. I suddenly could not access my account on this forum . I tried contacting admin but was not successful. Whe I tried to sign in I got a message that I needed a verification code from my phone app but could not get an app on my phone. Enough about that! In answer to your question about the throttle cable, I did buy a cable but did not have to install it. The stepping motor turned out to be the culprit. I ordered a new one from MOTTROLUSA, used the information from Lachau above and fixed the problem. Sorry don't have a part number. Dennis