Hi all, I have a 1994 Hitachi ex120-2 that is running hot on hydraulics after about an hour. No alarms or indicators saying it’s too hot. Checked with a temp gun and it’s around 160°-175°. Oil cooler is cooling the oil difference of about 10-12°. Pilot pump like has surge of chatter, one tick every 1-2 seconds. (Is that normal?) Filters are good, oil is good. I have a DP sensor to replace next oil cooler screen is clean. Has lots of power. The controls seem a little fast. Wondering if the pump is running full throttle all the time. Which causes oil to get hot. After the DP sensor I was thing replacing the pressure sensors and then maybe solenoids. Any advice is appreciated. Thanks!
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Hitachi ex120-2 hydraulics overheating.
- Thread starter TLogging
- Start date
Diesel Dave
Senior Member
Sounds like the hydraulic pump is in maximum displacement. First things , locate the PVC and EC controllers under the plastics behind the operator seat. With key on, the LED lamp on each controller should be flashing approx once per second indicating they are powered on. If the lamps are flashing you can check for any service codes.
You can check for fault codes using the red LED on the PVC controller.
See the link to an older thread below.
Post #14 shows how to enable the self diagnostic which sets an LED flash sequence, (if there are any codes).
https://www.heavyequipmentforums.co...u-load-the-hydraulics-on-hitachi-ex200.31811/ .
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The PVC is the bottom controller and EC is the top controller.
Ignore the light on the EC.
if there are any codes ,the LED on the PVC will blink in a pattern of long and or short sequence.
You can check for fault codes using the red LED on the PVC controller.
See the link to an older thread below.
Post #14 shows how to enable the self diagnostic which sets an LED flash sequence, (if there are any codes).
https://www.heavyequipmentforums.co...u-load-the-hydraulics-on-hitachi-ex200.31811/ .
.
The PVC is the bottom controller and EC is the top controller.
Ignore the light on the EC.
if there are any codes ,the LED on the PVC will blink in a pattern of long and or short sequence.
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Diesel Dave
Senior Member
No. The info in the older thread I referenced has the details of how to check codes.
Diesel Dave
Senior Member
Can you recheck the codes ?
- on a -2 machine there are no codes higher than 32.
- See if any new codes with the new issue
- on a -2 machine there are no codes higher than 32.
- See if any new codes with the new issue
Disregard this, I blew a hose yesterday and it was low on oil. I think it just had air in the lines.
Diesel Dave
Senior Member
You can upload the video to a platform like utube and post the link here.
I will message you my contact info in the meantime.
I will message you my contact info in the meantime.
Diesel Dave
Senior Member
I watched the video came up with the same codes as you 4 20 31 35 37 38.
Try clearing the codes. With key on , remove the jumper at the DrEx connector. wait a couple of seconds and reapply the jumper.
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Diesel Dave
Senior Member
Anyway , we are assuming the hydraulic pump is in max displacement. Prove it by backprobing the hydraulic pump angle sensor terminals #2 and 3. With key on , engine running and the pilot controls in neutral , if the pump is in max displacement the angle sensor output voltage will be approximately 4.40v - 4.45v DC.
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Diesel Dave
Senior Member
Try clearing the codes, report back the results
I'm curious why you want your hydraulics to run so cold?
Or think that is too hot?
I am happy when mine finally warm up to that. Doing the math, that is 71 C to 79 C, a normal oil temp, not high.
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Diesel Dave
Senior Member
Key question I neglected to ask , does the engine want to stall when any hydraulic functions are held over releif ?
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Because of this thread, I really paid attention today, while I was out on my case skidsteer, doing farm chores. My gauge is metric, so that’s why I did the conversion from 160-175⁰F into Centigrade, was for myself. I do know that my hydraulics work better and better, as the hydraulic oil heats up. When running some attachments that use a lot of hydraulic power, such as a trencher, snowblower, auger, etc. I've seen the hydraulics oil reach into the low 80s C, and its still in the green on the gauge. My gauge is in the yellow when its cold, and then once up to 46 C or 115 F, it finally shows it in the green. The green continues until its at 85 C or 185 F. At 86 C or 187 F the gauge shows it in the yellow, and the yellow continues up to 99 C or 210 F, where it then shows it as being in the red.
So since this is about being in the range of 71 to 79 C, I was just curious is all, as to why the original poster felt that was too hot, is all. I'm often worried about pushing any and all, of my equipment too hard, when the hydraulic fluid hasn't sufficiently warmed up. Same with engines, transmissions, differentials, etc. I tend to baby my stuff, until all fluids are warmed up, and that goes so far as frequently taping cardboard partially over oil coolers. Right now it's been fairly warm weather here, today it was 10 C or about 50 F outside, not too bad for March 4th where I live, so I have the cardboard removed from my equipment, including tractors, even my airplanes. But I tend to cover them somewhat when its colder out, even blocking the radiator ram air grill on my ATVs, to try and get them to warm up more, as running too cold, is actually hard on stuff. I ride my Can Am ATV almost every day, its how I get around on the ranch, or in the bush when logging. On the digital dash, the display can be changed to show 1 primary thing, and a few secondary items. I leave it set to water temperature, as the primary thing shown, and never get hard into the throttle until its at a minimum of 85 C or 185 F. Maybe I worry too much, I don't know, but I do like stuff warmed up.
Tomorrow I plan to fly my personal plane, and will still have its engine oil cooler, partially blocked off, despite the temps being relatively warm outside. On cold winter days, its not uncommon for me to fly with it 3/4 blocked off, as my planes engine is air, and oil cooled, not water cooled. Its very hard on the planes engine, if the oil cannot warm up. I'll pull it out of its heated hangar, and fire it up, let it run until the oil temps into the green, before applying take off power. If on my flight down to kamloops, the oil temps not running in at least the middle of the green area on the gauge, I'll block off more of its oil cooler, before I fly back. I prefer it to be 2/3 - 3/4 of the way up into the green, but can live with at least half way.