Hitachi EX100-2

[Jason Klassen]

Was a solution found to this problem? I have a very similar issue on my ex120-2.

https://www.heavyequipmentforums.com/threads/ex120-2-system-base-pressure-too-low.94910/

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.

 

[TheMethod]

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.

Did you ever reach a resolution on this issue? Would like to know what you found as the root cause.

 

[bc timber]

I too can hear bypassing in the control bank and very week hyd on all functions. any more information would be great.

 

[Jason Klassen]

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: https://www.heavyequipmentforums.com/threads/ex120-2-system-base-pressure-too-low.94910/

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!

 

[bc timber]

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

 

[bc timber]

I should say the bypassing you can here is when any function is applied tracks or boom stuff

 

[TheMethod]

Hey bc timber and TheMethod, check out my thread: https://www.heavyequipmentforums.com/threads/ex120-2-system-base-pressure-too-low.94910/

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!

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.

 

[bc timber]

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

 

[bc timber]

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

 

[bc timber]

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

 

[Jason Klassen]

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.

 

[bc timber]

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

 

[bc timber]

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