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Dan, Technician
Category: Construction and Road Equipment
Satisfied Customers: 4291
Experience:  17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.
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My komatsu wa250 starts but does not move and the coupler is

Customer Question

My komatsu wa250 starts but does not move and the coupler is good
Submitted: 3 months ago.
Category: Construction and Road Equipment
Customer: replied 3 months ago.
We went through all the hydraulic pumps, the forward and reverse motors, and electrical connectors.
Expert:  Dan replied 3 months ago.

Hi my name is***** will be glad to try to help What is your machine serial number and complete model with dashes at the end?

Customer: replied 3 months ago.
Wa250-6 serial#75210
Customer: replied 3 months ago.
VIN# *****
Expert:  Dan replied 3 months ago.

Thanks for the info. What was done to the pumps and motors and was it done by a certified rebuild shop or in your own shop? Were the pumps calibrated on a test bench?

Expert:  Dan replied 3 months ago.

If the coupler is good but you have no pressure check the filter internally for fine metal debris indicating pump or component failure. Let me know the results

Customer: replied 3 months ago.
Hello Dan
Our original Hydralic pump went bad
We found a lots of brass in the filters ??
We bought a used pump we went through it to make sure every thing is good and we flush the system and bought new filters
Expert:  Dan replied 3 months ago.

Have you lost all functions or just travel? Click on this link for the breakdown. The work equipment pump is bolted to the HST pump so back out the Hyd pump and see if the HST is turning the hydraulic pump. Recheck the filter for metal for a potential new failure. Let me know!0!12!4620!44!52

Customer: replied 3 months ago.
It only starts it doesn't do any thing else we recheck filters they are very clean we cleaned the Hydralic tank hoses and the whole system we put new oil
Expert:  Dan replied 3 months ago.

If the pumps are turning but you are not getting any flow or if you are getting flow but no pressure, check your relief cartridges for debris and damaged o rings causing a bypass of pressure and the relief to stick.

Customer: replied 3 months ago.
The 2 cartridges are before the main pump looked ok when we flushed every thing so is there a way to test those cartridges ??
Expert:  Dan replied 3 months ago.

If actual pressure is low or non existent when gauge testing then either the pump is not putting out proper GPM which needs a flow meter to test or a visual inspection of the relief valves

Customer: replied 3 months ago.
Where are the relief valves exactly??
And how can u test them ?!
Expert:  Dan replied 3 months ago.

The reliefs are in the main control valve for the functions and there are also reliefs in the drive motors themselves. On the link i posted you can access the complete parts manual to check all the parts breakdowns to assist in identifying the components and their breakdowns. Let me know

Customer: replied 3 months ago.
We have a lots of oil pressure After the 3cartridges and the steering works so the articlaing pistons have oil pressure also ,there is a lots of oil pressure from the value by the left side access by the Hydralic filter ?we Inspected the control valve from the front accses every thing looked fine ??how can we Ck the relief valves
Expert:  Dan replied 3 months ago.

You remover them and inspect them as I originally mentioned for debris causing them to stick open and for damaged o rings or other damage. Remove the complete assemblies.

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