Hitachi 120-5 week hydraulics unless I deadhead any function

[anton_baydak]

Hey I’m having weak power to all functions unless I’m dead heading some function. Just spent 6k for a new hydraulic pump with no fix. What is my problem. Thank you

 

[KOBE STEEL]

Are you able to provide some more details, if you can I'm sure there are a number of readers that could try and help you get to the cause of your weak power issue on your machine. If possible, can you give more details such as...

What is the full machine model ( EX120-5 or ZX120-5 ?)

what were the functions that were not working before the pump was removed and has this changed after the new pump was installed.

Is the machine slow to operate in all functions or only some of them.

Have you carried out any cycle time tests or pressure test on the machine after the pump was installed.

 

[anton_baydak]

Hi. It’s a ex120-5. The diagnostics showed that the hydraulic pump#2 was weak. The new pump came with the test video showing good pressures. For example when I use my drives they are supper slow unless I hold open thumb button then it tracks normal. If I go to put boom down at idle I’d won’t lift the excavator unless I use any other function like open bucket or close bucket or even put pressure on swing. Then it lifts up

 

[KOBE STEEL]

Try starting at the pilot pump and check that the pilot pump pressure is adequate before and after the pilot pump pressure filter (these small aluminum filters bowls can be very hard to unscrew) , usually located in the pump bay. Some of the pilot oil is used to supply the main pumps positive flow control pressure via the main control valve.
the pumps flow control pressures can be checked during single travel operation off the ground to confirm if the flow control signal is being sent to the right pump at the correct pressure, usually 25-30 bar signal will put the pump at maximum displacement.

 

[anton_baydak]

Checked all of that put in a new filter. Still same problem. Track speed is slow and boom down no power unless I hold thumb open or close or boom out or in then it tracks normal

 

[KOBE STEEL]

measure and record the pump flow control pressures on both P1 and P2 pumps on boom power down while trying to lift the tracks off the ground, then record the pump flow control pressures again while doing boom down and holding thumb open or closed, what are these pump pressure readings after each test?
Do you by chance have access to a hydraulic schematic of your machine that you could post to me so that I can look in more detail at the the valve bank set up?

 

[Diesel Dave]

Do you by chance have access to a hydraulic schematic of your machine that you could post to me so that I can look in more detail at the the valve bank set up?

@anton_baydak and @KOBE STEEL , check your messages.

 

[KOBE STEEL]

@anton_baydak and @KOBE STEEL , check your messages.

Info received. Its a big help, Thank you Dave.