We just bought a Hitachi EX100-2. When we went and looked at it, ran great, hydraulics were fast, but were unable to actually dig with it. When we got it home and went to dig a hole I was very disappointed. Hydraulics are fast, but it is short on hydraulic power. I checked pressure at the pump and it is 4-4200 psi. I tightened the main relief valve the last 1/2 turn that it had left and no change in pressure. I pulled the relief valve out replaced all o-rings and zero change. I ordered a new relief valve thinking this one is just shot, that will be in next week. Does anyone have any other ideas of what could be wrong? Also does anyone have a parts book for this machine that they would part with? Thanks in advance, Andy
I can’t say if ours is a -2 or -3, I’ve not got the plate or othe books in front of me. Does this machine have the buttons on the display that changes priorities? Strong man Stick Boom I know ours performs different when those are adjusted.
It does, and I played with those. Those seem to change speed but do nothing for power
Was the surge relief valve pressure checked? I think Hitachi calls it an Overload Relief??
Where is that one located?
Incorrect term. Surge relief is correct, overload is the circuit relief. On the bottom of the control valve. Accessed from below machine. One half of the control valve will have 3 circuit reliefs, the other half will have one relief. The single relief is the surge relief. It is supposed to be set to 5300 - 5350 psi. System relief setting is 5000 - 5150 psi (both set with engine on "P" mode with hydraulic oil at 50*C). So the system has to be set higher temporarily to set the surge relief, then turn system down to it's setting.
Today I replaced the main relief valve, with no change. Then I screwed the surge relief in and also didn’t change anything. I cannot get more than 4200 psi on the outlet test port on the pump. All functions make the same pressure. Where do I go next? Angle sensor adjustment? Thanks.
Hi everybody, With symptoms like this. The first I will also do as Mr. MG guide. Next, I will check the UNLOADING valve set as shown below. When this valve set is stuck it will also cause the phenomenon of not being able to increase the main pressure.
what section of the service manual is that in? I’m having trouble finding it. What part usually sticks? Do I need to completely disassemble the valve to get to it or can I just take the plug out on the top and make sure the spool is moving freely with a magnet? Also, Will I have to drain the hydraulic tank again?
Ok, I’m seeing where you are at on the valve now. What you have highlighted in green is what the service manual calls the relief valve, and number 11 on your diagram is called main relief when the service manual calls it the surge relief. So now I’m even more confused. I have had the relief valve which I believe you are calling the unload valve out, torn apart, put together with all new o-rings, now replaced with a new one and have zero change in pressure. With it out I stuck a magnet down in the hole and was able to pull the spool under it up maybe 1/4-3/8” of an inch. Seamed to move up and down freely.
Please do not confuse the unload valve with the main relief valve. The unloading valve is at the top side and main relief valve is at the bottom side. The main relief valve has a screw to adjust, and the unloading valve does not have a screw to adjust.
The system relief controls the unloading valve. The unloading valve is underneath the system relief. They work in conjunction with each other to control system pressure. The system relief actually monitors load sense pressure and when load sense reaches the setting of the main relief (it should really be called a load sense relief) it then allows the unloading valve to shift dumping pump pressure. So what LACHAU is saying is the unloading spool may be sticking and not allowing the system to build full pressure. Here at Deere we call the main relief in his drawing a surge relief and the valve over the unloading valve the main relief.
So the spool that I can see when I remove the relief valve is the unloading valve correct? That seems to move with a magnet ok. Both the relief valve on top and the surge relief on bottom are adjusted all the way in, and I am only getting 4200 psi.
O-rings on the reliefs OK?
I replaced all of the o rings on the main(top) relief but I did not remove the surge(bottom) relief. I figured I’d have to drain the hyd oil to do that.
Alright, I really need some help guys. I have now adjusted the angle sensor to 4.412v, it was at 4.745 before adjusting. And also swapped solenoids on pump with no change. Could it be the DP sensor? I’m starting to lose sleep over this thing. Haha
Just to rule out something electrical, did you get the blink codes from the PVC (that would be the bottom controller of the two)? Looking into the diagnostic connector with the lock tab up, short the two terminals on the right with a paperclip. Key on and count the blinking codes. They will most likely be two digit numbers for a hydraulic related issue. For example, long flash, pause, long flash, pause three short flashes (23). There could be more than one as well. Post if any.
There are no blink codes at all, and controller blinks normally without jumper in diagnostic port
I wasn't aware that an EX machine had load sensing? Your symptoms sound kind of familiar to a machine I worked on over twenty years ago. Same thing happened, plenty of speed with no load, no power when trying to dig something across all functions. We got tired of all the things it could be and just pulled the pump down. We found the case bore for the swash plate control piston worn out and bleeding control oil to the point of not being able to produce flow at high pressure. Had to replace the pump case to fix the problem. Probably not what you would want to hear but something you should consider.
Pump was gone through by a reputable shop the same time as the engine was overhauled about 300 hrs ago. So I would think that isn’t the issue. You can hear the oil bypassing in the valve bank when you bottom out any function I’ve had both reliefs out and re-sealed now, also tried a new relief on the top with no change.
Was a solution found to this problem? I have a very similar issue on my ex120-2. HeavyEquipmentForums The pressure is too low at idle with the controls in neutral and my max pressure is also around 4000 psi instead of 5000 psi.
Did you ever reach a resolution on this issue? Would like to know what you found as the root cause.
I too can hear bypassing in the control bank and very week hyd on all functions. any more information would be great.
Hey bc timber and TheMethod, check out my thread: HeavyEquipmentForums I ended up having to replace my entire main control valve with a good used one from a wrecker. There were internal cracks in the casting casusing oil to leak back to the tank which stopped the machine from building full pressure. I could also hear oil bypassing and now with the new control valve that sound is gone. It's a bit of a read but there is a lot of info in that thread, too much to repeat here lol!
Thanks for the fast reply, muchly appreciated. I will check out thread. I can here mine say mid to lower section on right hand side. thanks
I should say the bypassing you can here is when any function is applied tracks or boom stuff
Jason, UGHH! I read it, and I don't like it!!! When my machine is at idle, I don't have any pressure showing for either pump... Pressure goes up once you activate a function but then will go back to zero. My machine is a 150-1, so totally mechanical, but same gremlins could be affecting it I suppose.
Morning, UGHH is right. With a gage on the test port 1/4 inch on pump beside the outlet i get 650 psi at idle and 2300 with A function on but if i hit another function with a tap well holding the first one on it will bump up to 2500 to 3000 and hold there till i let go, I here my bypass only when A function is on. i starting to lean towards the head also. I started looking for a main control not much here in Prince George bc , i will try checking the unload valve and the over load but from what i see here sounds like the main. its ever function is the same. thanks guys
I should say its an ex100-2 and has the manual convention kit so no ecms head 425 4645 . and pilot psi is 800, and only hear bypassing when a function is activated
Well, i went for pump rebuild, put back in and still no power, heres one with new pump main boom will not lift unit but if i pull stick cly with boom at same time it lifts great but if i try stick and travel or mix stick with any other function no power
Sounds like it could be a problem with the load sensing shuttle valves. Since your machine has the manual conversion it is unlikely to be the proportional solenoids that control the variable pressure compensated valves. The computer controls these for combined operation of functions. The shuttle valves are like little one way valves. Each main spool has one. When a function is activated the "load" works its way through the shuttle valves until it reaches the unloading valve. When it gets there it helps hold the unloading valves closed so that main pressure can be built up by the pump to activate the asked for function. If more than one function is called for at the same time like stick and boom the function with the higher load one it will over ride the others as they pass through the shuttle vavles. This way the machine is always sensing the highest amount of load. In a normal machine with computers the load holding down the unloading valve is also directed to the dp sensor and then the computer tells the pump to increase output based on value of the dp sensor. On the manualized machines I think there is a hose coming out if the top of the main relief valve and it takes this "load sense" oil to the manual pump controller on top of the pump where the electronic pump control solenoids would normally live. The load sensing shuttle valves are not easy to get to. They are on the back of the main control valve facing the metal divider between the control valve and the engine. There are 7 plugs with square heads. Looks like a little plumbing cleanout plug. With the plug removed you can see the back of the shuttle valve. There is a small hole in the middle with a m5x0.8 thread. Screw a tiny bolt into it and use it to yank the shuttle valve out. All of this is way easier said than done. I cleaned mine when I had the control valve out of the machine. Do you have a manual? The trouble shooting section can help you narrow down the possible causes of your issue.
Thanks for the info Jason, I back in camp working for a bit. then i have hunting camp till nov, so not sure when i get time but when i do i will post thanks
well i got it working. it was the o rings on the surge relief. it also had damage on it. Possible shrapnel from the pump. thanks for all the info guys