Hitachi Ex120 Problem

[-3Doc]

Another thing you can try is to swap the electrical plugs on the pump displacement solenoids on the back of the hyd. pump. If the problem goes the opposite way (everything super slow and no engine pull down) then you have a bad solenoid.

 

[tomex120]

Hi, I'm Tom from Ontatio, Canada. Did you find the problem with your ex120 stalling when under load (or cutting out) ? I have the exact problem with mine but it only happens once the machine is hot. When its cold it runs fine.

 

[tomex120]

Did you and spunkeymonkey solve the hitachi ex120 hydrolic stall problem, I have the same problem only when the machine gets hot?

Tom

 

[-3Doc]

Tom have you checked your fuel screen in the banjo fitting? I haven't heard weather spunkeymonkey fixed his problem.

 

[tomex120]

yes, the banjo fuel screen was clean and I .also replaced the fuel filter, but its still the same problem. any other ideas?

 

[-3Doc]

If it is only doing it when hot it may be one of the pump displacement solenoids starting to break down electrically, what you can do is swap places with the two solenoids and see if the problem goes the other way and the machine becomes very slow when hot.
they are held onto the pump with 4 allen head bolts, just unplug and change places and plug back in and give it a try.:canada

 

[-3Doc]

Tom what machine do you have ? An EX120-1 ,2 , 3, or 5.?

 

[tomex120]

I'm not sure, how do I find out?

 

[tomex120]

I just checked the machine and its a ex120-2

 

[-3Doc]

Here is a breakdown of your pump, the two solenoids are up on top, release the pressure in the hyd tank before you swap them.

 

[Pgentech]

Hmm

Very interesting Can anyone help me find a manual for teh 120-2?

 

[-3Doc]

I can supply you with one if you are interested. Just PM me.

 

[tomex120]

I narrowed down the problem with the ex120-2 cutting out when hot. It was the displacement solenoid valve, The electrical coil was crack and that was because the two oil seals behind the coil leaked and would slowly preasurize the electrical coil and expand it, then cutting out the coil circuit ( the coil is 18 ohms resistance) then the excavator would start to cut out. I fixed the seals and now its OK, but I would still like to replace the coil or solenoid. Does anyone have one ?

 

[tomex120]

-3Doc. How much do you want for the ex120-2 manual?

from traepple@golden.net

 

[andre01]

I have a JD 490E excavator, the engine stalls whenever i put load on the hydraulic functions, tested the wire to the displacement solenoid and no current, also testing this wire shows the - (negative) is not grounded, no continuity with grounds. so it seems i have a current problem, if so , is it the computer that controls these solenoids. what to do? plz help.

 

[andre01]

also i disconnected the solenoids and tested them they are both working , but when connected on the excavator no current is going to them. i took off the connector and connected one directly to the battery via a long wire, and the machine moved very slowly but did not stall, however when i connected both of them to the battery the machine stalled as before.

 

[AtlasRob]

I have a JD 490E excavator, the engine stalls whenever i put load on the hydraulic functions, .........plz help.

Now you have 3 posts you can start a new thread.

Having a quick scan down the thread titles should give you some idea what to use as a title to get the help you need.

eg, JD 490E stalling under load. Advice please.

Copy and paste what you have already done and discovered here and see how it goes.

 

[-3Doc]

also i disconnected the solenoids and tested them they are both working , but when connected on the excavator no current is going to them. i took off the connector and connected one directly to the battery via a long wire, and the machine moved very slowly but did not stall, however when i connected both of them to the battery the machine stalled as before.

With the key on and engine not running you should have 24volts to one wire on each of the displacement solenoids, (the ground is controled by the computer and you can not check this easily.) If you don't have 24 volts to each solenoid then you can check the fuses first there is a one amp fuse for each in the fuse box. Make sure they are good then go from there and check the wiring from the fuse box back to the solenoids. Hope this helps.:canada

 

[Janni]

Worth checking it out
Every pump has solenoid or what they call proportional valve that make your pump to de stroke (since you said you have black smoke and then recover) so connection to PPV (inside or behind you’ll have check valve, it has to move freely) are very important and if you have some twisted connections(new wire harness) each connection will loses connectivity so eliminate that...
Good luck

 

[duck_nutt]

I can supply you with one if you are interested. Just PM me.

I"d be very interested in an operators manuel if you have one....my father in law just purchased a 1992 Hitachi EX120-2....he's been doing dirt work for 30 years, but all with a backhoe and dozer...the excavator is new to him, and all the instructions in the cab are in Japanese...

duck_nutt@hotmail.com


ANY information you can send on the EX120 would be greatly appreciated