Hello Everyone I have unhealthy EX120-2 and trying to figure out whats bugging it. The engine runs (idles fine, revs up etc.) But the hydraulic and tracks are slow and the engine does not seem to be under load when using the bucket etc. Reading other posts, I think have a bad solenoid. So I pulled the two pump solenoids off. The front one had a crack right thru the coil and it was covered in oil. The second solenoid had a small crack but not completely thru the coil, it was dry no oil. So I replaced both soleniods with new parts thinking I have solved my problems. Start her up same issue. Digging deeper I metered the voltage with just the key on, engine not running. The front solenoid connector has 24v, the one behind it as 11.5V (bounces around to 12.5V). I doubled checked that I had a good contact on my multi-meter. From reading on the fourms shouldn't they both be getting 24V. I checked the fuses, they are OK. From what I can see of the wiring it looks OK, but I have not gone over every inch with a fine tooth comb. Would it do any damage to switch the connectors on the solenoids around? Also the PVC computer was replaced in August 2010, because it was blowing fuse F7. This hydraulic problem started shortly after the computer was changed. Sorry for asking so many questions, loving learning about how this machine works and enjoy reading the posts on the this fourm. Maybe someday I will be able to give something back. I have also seen on the web were I can purchase service manuals, parts manuals etc... pdf downloads for $30 to 150 dollars depending on the manual. Would these help me or are they all in Japanese. I would hate to buy them and not be able to read it. Thanks
This might sound stupid but check the connector at the pvc computer.
Have you managed to solve this problem? We are experiencing the same problem with the EX200-3 model. Does anyone figured out the cause of the slow hydraulics? Cheers all!
i can help you with your problem sir. call me at 09173232700.
there is a lot of sensor failure of this machine with the same symptom. dp sensor, angle sensor, pump solenoid, pvc, pressure sensor, and rpm sensor. any of this sensor failure would result to slow hydraulic movement. check all the wirings of this sensors. hope this helps
Hitatchi ex200-3 hydraulics Hi all has anyone had slow hydraulics on hitatchi ex200-3
Any joy with your hydraulic problem on ex200-3? Cheers.
Can you still help us with the same problems as the earlier post, I have a Hitachi 120 with slow hydraulics I have put one solenoid on swapped the wires when the wires are swapped all the hydraulics function correctly but if you try to walk it or do more than one function it stalls out we have replaced the PVC controller with no avail
I had a hitachi 150 that would barely move, the screen in the hydraulic tank was plugged. Get your longest rubber gloves on and yank it out!
Hello from Louisiana - I have a Hitachi EX120-2 with the same problem (approx year 1994-1995). Here are the symptoms: Fire the machine up first thing in the morning, it will function fine for 30-40 minutes then all of sudden the hydraulics come to a crawl. The engine still runs fine, not issues here; will idle and rev up. Turn the machine off, let it cool for 20-30 minutes, fire it back up, the machine will function normal for 5-10 minutes then come to a crawl again. Checked all the fuel and hydraulic lines, changed all the filters. Had a mechanic come out and test all the sensors which displayed they were functioning normal. I just ordered a "ex120-2 main relief valve" which should arrive middle of next week, I'm not sure if this will solve the problem. For those of you that had this problem and solved it, could you please take a moment to post what fixed the issue?
dsharp, I have the same machine that was doing the exact same thing. On mine, travel would go away first, then boom functions would go away. Mechanic told me it was classic worn pump symptoms. One new pump later, it still malfunctioned, although in a somewhat different way. I finally noticed that jiggling the connector at the PVC (like DirtHauler mentioned above, although I found it on my own) would straighten it up for a while. The jiggling "sweet spot" has gotten harder to find, sadly. It will either kill the engine or not move. I think a new wiring harness should solve my problem, but I just can't stand the thought of spending all that money and not fixing it. You need to find a mechanic who has the DrZx reader and knows these machines. I had one out one day, had all the test equipment and a lot of spare parts, but the damn machine operated perfect all damn day. The next day it went 15 minutes before crapping out.
An update - the relief valve came in today... nope, didn't solve the problem, so that isn't it. I'll keep posting updates. @wilko - thanks for the information, I have not tried that, but will give it a shot. Did you sell the machine like that? or still using it?
Still fighting it. These machines are famous for electrical gremlins, diagnosis is tough, throwing money at it is a bottomless pit. At least parts are available on ebay. Go to the dealer and it's much more expensive.
hey DS harp. Sounds like your DP sensor is shot. Usually the coils the thing that goes and Chinese ones are dirt cheap and last around 6months max, but at least they are cheap enough you can keep a box of em and not feel bad about it. I am 80% sure its the DP. I haven't bought any on Ebay but basically you can get one for under 100 bucks.
@wilko - tried to move the wire around this morning, etc. that didn't solve the problem; Didn't notice any difference at all, but thanks for the suggestion. @digger_hunter - I purchased one of those a few weeks ago, but it was for the 490E John Deere. When plugging it in (machine was cold, had not started from the previous day), nothing functioned, I put the old one back in and the machine operated fine for 30-45 min before the hydraulics went to a craw. I'm going to buy one specifically for the Hitachi EX120-2 to see if that will solve the problem. I also ordered the Hitachi Dr. Ex Scan Tool from sinocmp.com. It should arrive end of this week, so hopefully I'll be able to plug it in and get some results on pressure, temps, electrical components. I'll keep everyone posted on my findings. What's interesting is that there are people that have these types of issues, but they never come back to post what actually solved the problem.
hey Sharp. We had the same fault as yours. Tried everything man! I bought no less than 3 sets of the Dr EX and nothing worked. In the end I got the correct software and bought the correct cable from JD and guess what worked straight away. Very good to have that tool but I'm afraid it won't help much solve this problem. I would suggest you look at the small solenoid Valvebox and reseal it. Thats what did the trick for us in the end. I can't remember exactly what but I think it had to do with how that solenoid Valvebox affects the load on the DP sensor. So too much pilot oil makes the DP think more flow is needed and maxes out the pump and ends up being dumped as excess heat. If you need the manual let me know I have a copy I can send you. But try resealing the O rings and seals on that solenoid Valvebox as you probably need to do it at somepoint. Ours was well messed up since the machine had overheated several times and the hot old had cooked the seals.
PS: I have the software for the Hitachi that someone on this forum gave me, WinDR I think and I also have the bill for the cable (pretty pricey I think!) but it does work
@digger_hunter - I purchased a manual, which has been super helpful! I'm thinking I should get a new DP Sensor right away, mine did come from China. Maybe I'll order a couple... Just so I understand, the Solenoid Valve or the DP Sensor could cause the pump to run at a max output, which in the end, heats up the hydraulic system causing it to come to a crawl? I have noticed, but have not confirmed temps yet, that my hydraulic fluid gets pretty hot. Thank you so much for taking time to answer these questions. I'm sure that others will have the same issue, at some point. Maybe we can make their life much easier.
hope so! Yeah the hydraulic oil gets so hot that it actually melted the plastic of the level tube! So you can imagine what it would have done to the seal. We needed up replacing every seal and o ring on the machine after that because the operator just worked it till the thing boiled over several times! at first it was a faulty dp sensor. but one of the solenoids end up loading the pump as well if the oil starts bypassing it due to faulty o rings
@digger_hunter - Mine hasn't gotten that hot yet. We shut it down, however, I bet those seals need to be replaced. Where can I find the actual o-ring sizes, etc for those valves? Is there a parts diagram somewhere that shows the breakdown of the valves with part names and part numbers?
@digger_hunter - I've ordered another DP Sensor, it will be here tomorrow. All others reading this post: I recently learned that http://finneycorp.com/ out of Birmingham, AL has most, if not all all of the sensors for the Hitachi machines. Another member on the forum informed me about them. They are great people and super helpful! Their number can be found on the website.
Hi, do you know if they have genuine DP sensors? I have been looking for genuine ones for ages and looks like its out of production so cheap Chinese made ones are the only option. From my experience, we have experimented with all kinds of these sensors and controllers from China and some from Korea and the only thing thats bad is the DP sensor. looks like a seal fails and lets in old into the coil part and that messes up things. However the rest of the parts like the pressure switches (around 10-15 bucks), computer around 300, angle sensor around 50 were all very good. The DP and also the high speed solenoids are the culprits. Even the high speed solenoids, if you are craft you can get the cheap coil into the valve body of the original and its better.
@digger_hunter - I do not know if it is genuine. I assume that it is not, but not certain. I can take a picture of it and post it here when received. Thanks so much for pointing out the solenoids, I'm definitely going to replace the seals on them. I'll keep you and everyone posted.
An update: The new DP Sensor I ordered came in yesterday. Bad news, did not solve the problem. Currently going off of @digger_hunter recommendation and replacing all the seals and o-rings in the "Solenoid Valve Assembly". Waiting on parts to come in. Will keep updating as I have information.
Update: Nothing new at this point. I resealed several of the values in the "control value"; installed a new A-Sensor (angle sensor). Going to do a little more testing on the machine this coming weekend.
Dsharp, did you replace the high speed solenoids on the pump yet? They can cause exactly what you are describing - I've heard of the coils sometimes getting a break in the windings that closes up when they're cold, then when they get hot things expand just enough to break contact and then they stop working. When you go to test them with a meter they've usually cooled off enough to have continuity again and you move on thinking they're fine. Annoying as heck! One thing you can try is to swap the solenoids around, they are identical And see what happens. If after the usual 30-40 minutes it starts to bog down and really move fast or starts labouring the engine and blowing black smoke then it's pretty sure to be the solenoids. Hope you get this sorted out soon!
Dean the stuff you sent me yesterday ,what I read of it, will be a big help. I bought pressure gage and going today and get fittings to check pilot pressure.
@spitzair - I have to tell you that this machine is driving me nuts! Just so you understand my problem, after 20minutes of the machine running, the hydraulics come to a crawl. The engine still runs as normal, will idle and rev up. Yes, new solenoids, here is check list of things I have done: - All new fuel filters. - All new hydraulic filters. ... Removed Hydraulic tank, had it cleaned, pressure tested and flow tested. - Replaced: ... (new) Main control valve (the valve in the center of Control Value) ... (new) Both solenoids on top of the main pump. ... (new) DP Sensor. Actually two of them based on reading that sometimes you'll get a bad one. ... (new) Angle Sensor (A-Sensor) - Checked/Resealed ... The three relief valves in the Control Valve ... Pulled the solenoid valves in the "Solenoid Valve", located just behind the cab. ... Swapped the solenoids on the valves. ... Had pressure (w/ gauge) at main pump @ 5200-5400 lbs. ... Had pressure (w/ gauge) at pilot pump @ 700 lbs ... Had a computer hooked to the machine, tested all electronics, no fault codes anywhere. Pressures displayed from computer program were reading perfect. The only thing that I haven't done yet is to reseal the "solenoid valves". Meaning, pull the sleeve out of the body and install new o-rings. Hope this helps; and would appreciate any other things to try/test.
That's a tough one... Something seems to be preventing the computer from knowing when to stroke the pumps up, just to find that gremlin will be the fun part. Another thing it could be is the actual mechanical mechanism in the pump but I doubt that. Have you checked the pilot sensors on the blocks behind the cab? There are 2 rectangular blocks on the floor of the compartment just behind your cab that all your pilot lines run through with sensors on them that sense when you move the controls and basically tell the computer that something is about to need flow, and if those don't send the message along they could cause these problems. Could be that these sensors stop working when they get hot or maybe a wiring issue somewhere in there...
I've thought on my machine that it would be nice to tap in to the wiring at different points (like the solenoids, angle sensor) to see what kind of voltage readings you are getting when things work vs. when they don't. Would need to ground the test meters through the computer and perhaps straight to the battery in case the ground for the computer is weak, which could be the cause of your problem all by itself. Electronics problems are the worst.
I just got in from working on my 490e there's a lot of ground wires underneath when you take the covers off the bottom. I going to check them along with the pilot pressure tomorrow.
Got my Dr zx and it tells me to check connection. After about 30 time of plug and unplugged still saying same thing. Any suggestions
Hey guys. Haven't checked in a while. D sharp. It might be worth you getting hold of a diagnostic cable from JD. I can send you a contact. I think it's around 300bucks. I tried so many of those DRZX stuff on eBay and threw them out as nothing worked except the genuine cable with the software which I can send you. It shows the position of all the sensors and pressure readings etc live so you can see what's happening when the problem occurs.
I'm having same problem... What was your issue?
dsharp and others, with all the problems you blokes are having with these older machines and the time and money you are throwing at them, would it not be better to rip the electronics out and replace with a old school pilot controled system? I worked these machines new back in the day and were great little jiggers, reliable and rugered. Seems to me everything has a use by date that is getting closer to the purchase date.
Tones, more detail would be appreciated.
Wilko, I have read somewhere on this board that there is an outfit that makes a hydraulic loom so that the electronics can be removed. If what I read was correct then I reckon it would be a great option. A hydraulic shop owner who I deal with said that it can be done on the machine I own. It's not an excavator but even more complicated.
Can you blokes who are having problems with Hitachi's 1, tell us the age and engine hours 2, post a photo of where the suction line for the pilot pump connects to the system I have some info which suggests your problems may not be electronic.
Dear all Please find attached note which solved our problem similar to yours.
So just had hitachi out to look at my hydraulis as the motor stalls out when you use inputs. All seems fine regarding pump and pressures, however no power at scan tool connection. Mechanic thinks I have wiring problem.... I am thinking about installing conversion kit to manual. Has anyone used this kit? I use this on my farm so can't afford to dump a pile of money into it. (Early 90's ex120~2)
As I haven't had any responses on my post regarding my JD 790 staying on high pressure, the 'DP' sensor mentioned several times here I assume is the Discharge Pressure sensor? I replaced mine with a Chinese made unit with no change. I jumpered in a rheostat before the sensor plug and could vary the voltage return from 4.8 (no load) down to 2.2 (mid load) and could change the engine load and pump output at will or disconnect it (no voltage return) and go full tilt. This test is making me believe the sensor IS the problem and maybe the new unit is faulty also from the post #22 that these from China are often bad new. Do I take the risk and get another from JD?
I would say you are correct. I bought a China sensor for my Cat. I had the same problem after installing the "new" one. I measure the voltage while engine off/running, Etc and it did not vary like it should. Of course the seller didn't believe me so I took a video of it in operation. They refunded my money. I bought 'another' one from China and it works great.
Thanks CatKC! I am going to take the risk and added expense and get one from my JD dealer which hopefully will be a non chinese made unit.
The JD ones are likely 'foreign made' also but they will probably be 'tested'. If you have the time you can always try another one from China. I tried again because the -price difference- was $85 vs $400 + and I was in no hurry.
I'm in a bit of a hurry and checking online, JD's price is $175 so hopefully I can get up and running soon. Thanks!
I have a JD 490 E and have been fighting to find my problem with the main pump control system for 6 months. The electronics on the machine are a PITA. The machine's engine runs fine but after a couple of hours of operation it ran hot because the main pump was putting out too much flow. I have been through more than I have space here to delineate, including two service calls by JD techs, but long story short it turns out both the the pilot system regulating valve and pilot system control valves were bad. Neither met pressure specifications, both being low. The DP sensor saw the low pilot pressure as a demand for more flow and signaled the PVC to increase the flow. The increased flow simply went through all the pressure relief valves making heat in the process. I am still in the process of readjusting all pilot control circuits. I have learned a lot about this machine and how it works in this process and overhauled or replaced many unnecessary parts. To those resealing the pilot control solenoid valves, read the service manual and put the sleeves back in with ports oriented to the valve body ports. Initially I did not, which caused wild pressure spikes and made proper solenoid adjustment impossible. That issue caused a complete job redo. I now believe the heat weakened the springs in the pilot system control and regulating valves accelerated the over pressure/over heating problem. The machine had always run on the high side of the green range since I have owned it. My operator slid the machine into a pond and in a panic to get it out, disregarded the heat gauge, which significantly increased the overheating problem. Along the way while trying to get all systems into specification, I was trying to get the pilot pressure regulating valve up to the specified pressure by adding shims. The manual said a 0.010 shim should give a 20 PSI increase. When I added a 0.010 shim, I was getting less than a 10 PSI increase, so I kept adding shims until it locked the regulating valve closed and blew the pilot filter housing into 4 parts. Then I read such a blockage could/would cup the head of the pilot pump and reduce its capacity by 40%, so I had to get a new pilot pump. Lesson learned: If it does not respond as the manual indicates, STOP AND FIX THE PROBLEM before something else expensive is destroyed.
A good point. If you are not getting the expected results, STOP and rethink what you are doing. Do not continue to attempt to force the results expected. I'll confess I have done the same thing, but fortunately it did not turn into such a costly mistake.
An update on the Hitachi EX120-2... I'm still in the same boat. I brought the machine to have it looked at but in the end I'm experiencing the same results. Just doesn't make any sense. All pressures are good coming from the main pump and pilot pump. I've replaced just about every sensor on the machine, all filters, computer, you name it. Around March, when it warms up, I'm going to see if I can figure it out again. I haven't "resealed the solenoid valves"... I think I'll start here. If there is anyone in the area that has the tools, knowledge and thinks they can figure it, message me.
dsharp-This is really old but did you ever fix your machine?
I fixed mine, but it was a PITA. After going through most everything (read expensive and time consuming) it turned out to be the pilot control system. Neither the pilot control regulating valve nor the pilot control reducing valves would meet pressure specs when tested per the manual. Along the way I replaced a lot of components, including having the main pump disassembled and inspected and replacing the pilot pump. I also resealed the pilot control solenoids. Those solenoids are actually flow balancing valves that are electrically controlled. Setting the balances requires that function to be in operation.
Thank you, I feel mine has the same problem as yours. I have replaced about everything and it operates great for about 30 min before going into slow mode. Just feels like hydraulic fluid is bypassing. Are the pilot control regulating and reducing valves hard to fix?