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!
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). HeavyEquipmentForums . . 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.
Sounds good, I will check tomorrow. Is this what you are referring to?
No. The info in the older thread I referenced has the details of how to check codes.
Got the codes, 4, 20, 31, 35, 37, 38.
Just started the machine up after checking codes and now the hydraulics are very slow and choppy. Hasn’t done this before. Could checking the codes have caused something to short out?
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
Disregard this, I blew a hose yesterday and it was low on oil. I think it just had air in the lines.
Just checked again and everything is the same. Long blinks 10’s and short blinks 1’s? It’s a grey market machine. Not sure if this changes anything?
I have a video if there’s a way to send it to you. Maybe email?
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.
Here’s the link.
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.
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.
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.
Key question I neglected to ask , does the engine want to stall when any hydraulic functions are held over releif ?
Confirming you are correct. Over 100c would be hot. Crazy to fix what ain't broke
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.
Sorry for the long post above.
I do exactly the same with my John Deere Skidsteer. Move very slow until engine up to 160F and then increase slowly until 180F. I need almost every vent blocked for it to warm up in the winter, and always blockheatered for 3 hours before starting. Simon C
Here is a way to warm up hydraulic oil prior to work in cold temperatures and was the warm up procedure for UH series Hitachi excavators. With the dipper fully extended and the bucket ram fully retracted, allow the engine to warm up, then at half throttle hold the bucket lever in the dump position for 5mins. Next hold the dipper lever and bucket ram lever in the ram retracted position for 5mins with the engine at WOT. Then go to work. Pumps on those machines were good for 14-16 thousand hours if serviced and warmed properly. I don't know of any reason why you couldn't do this with your machines in cold climates.
I got an optional hydraulic oil heater on my skid steer. I'm not sure if it's even an option on most other brands.
A customer of mine has a Deere 210G excavator with a diesel fired heater that goes through the hydraulic tank before going through the engine in a loop. Even at minus 30C his machine starts and is ready to work in a hurry. Not as hard on hoses either. Simon C
I was basing my assumption it was starting to run hot because I have a komatsu feller buncher and have been told by multiple operators to keep temps below 160°f if possible. It’s been cool weather and it was running that hot I was concerned when it warms up it would get too hot. Just wanted to get ahead of any issues if possible. I tend to worry too much about my equipment. Ounce of prevention worth a pound of cure! Also, cleared the codes and will run it some more. Could the codes be different because it’s a grey market machine? Also, no stalling issues. Has lots of power.
1 cents worth of worry can cause dollars worth of curse
What’s the serial # of the machine ? Are there any part # ‘s on the EC or PVC controller casings ? . The fact that your machine has lots of power and the engine is not stalling under load ,sounds like the hydraulic pump is not stuck in maximum displacement and the pump displacement control is working as designed.
@TLogging , that serial # you posted is legit for an EX120-2. Lots of people on this forum with same serial # format. I suspect the EC and or the PVC are aftermarket parts resulting in unique service code #’s.
@Diesel Dave I will check for that. What would cause the hydraulics to be inconsistent? Notice the last few days when I let it idle for 10-15 mins when I start working it again the hydraulics are very jerky, barely move or very jumpy. Also this is after it running smooth for 3-4 hours. If I move the thumb or curl the bucket eventually it goes away.
Gotta love intermittent problems. Having DrEx live data in this situation would be ideal but try old school for now. Battery voltage is steady with engine running ? should be around 25.0 -27.5v. . Try swapping the 2 solenoid valves on top of the pump, do not swap the wire harness connectors. See if anything changes. . With a volt meter and backprobing sensor terminals #2 and 3 , Monitor the sensor output voltage at the - DP sensor . With pilot controls at full movement output should be approx .50v. With pilot controls in neutral , output should be 4.5v - Pump discharge pressure sensor at 5000 psi output should be approx 4.5v, pump discharge pressure at 400 psi output .60v Measure the sensor output voltages when machine is functioning correctly and try again when the hydraulics are slow/ jerky.
An electronic bypass kit may be your best option for this machine. I've installed a couple of those and they worked out quite well. Look on Ebay or google search "electronic bypass kit for Hitachi -2 excavators. It does away with the pump solenoids and converts the pump to a manual regulator setup. The instructions aren't great but I was able to get them to work. Hope this helps.
@ohdeereme , you sir are about to become a very popular guy .There are numerous Deere / Hitachi hydraulic pump “conversion kit“ install threads here mostly dealing with poor machine performance after installs. Good to hear you have some success !
The instructions do leave a lot to be desired. One I installed stayed at max angle and another one wouldn't work at all. Both turned out to be a plug in the port in the bottom of the new regulator that went to the decrease end of the servo and the other on was vice-versa. I spent a lot oa time working on Deere 490E's and 790E's which use the same electronic control system as the -2 Hitachis. They were the most aggravating machines I've ever worked on, I've went home with several headaches because of them!
I have heard you lose a little power when making the conversion. Is that true?
I replaced the hydraulic fluid and filters and the machine had not had any of the inconsistencies/jerky functions unless it is getting hot. I have noticed when it has idled for 10-15 min the power is reduced to about 60-70% when at full idle. If I shut it off for a few minutes and return it to full idle it has tons of power. Only time I notice it lose power is when the hydraulics start to get around 175-180°F.
Machine had no start today but has good power, when looking around I found this braided copper strap loose on one end. Should i reattach it to the starter mounting bolt or should it go somewhere else. Also would this cause or contribute to the low throttle issue after idle?
That strap could very well be the cause of the problems, take it off and clean up both ends and were it mounts then reattach. A poor earth causes lots of problems.
Copy, got it back on and still won’t start. I checked the battery relay and have 24v leaving it. All fuses are good and everything on the starter is tight. I can hear a faint click at the starter. What else should I check? Also, found the control cable at the T-link for the governor control had come out of the bracket to hold the cable. I’m assuming that may have something to do with the idle inconsistency when the engine control motor adjusts? Will know more after I get it to start.
Does solenoid go clunk with your hand on it if someone holds the key in the start position. I like with a tiny hammer to rap on solenoid while someone holds the starter in start position. If it starts to crank you know the starter is done. Simon C
I should of asked, is it no crank or no start. Simon C
I’ll try that, I tried it without someone holding the key but didn’t work.
More often than not there's a copper plate that's at the end of the solenoid and goes into the starter motor body that gets corroded. Take it out and clean it. A good chance the starter will work again .
Actually, I knew a guy who use to silver solder the copper plate back up to full size to fix them. Yes they can be fixed, just depends what a guy finds inside if it is a starter issue. Simon C