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Dan
Dan, Field Technician
Category: Construction and Road Equipment
Satisfied Customers: 5544
Experience:  17+ yrs. shop and field experience with all major brands of heavy equipment, trucks and farm equipment - 1995 WyoTech graduate.
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1.) I had a problem regarding the LS120 Mitsubishi Excavator

Customer Question

1.) I had a problem regarding the LS120 Mitsubishi Excavator where I had replaced the main pump and also the small pump for the hydraulic control but the travel motor works soooo slowly and it doesn't work normally and what shall I do to correct the problem?
2. Also the same with the same model LS120 Mitsubishi Excavator I had also replaced the Main hydraulic Pump and the small pump for the hydraulic control but the unit when at its operation the engine even at high idle will shut down and what's the problem that we can solve it very soon.
Submitted: 1 year ago.
Category: Construction and Road Equipment
Expert:  Shantal-Mod replied 1 year ago.
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Expert:  Shantal-Mod replied 1 year ago.
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Expert:  Dan replied 1 year ago.
Hi Mario, Be sure the system is completely flushed and there is no metal/debris in the system or filter. 9 times out of ten slow travel is related to rotary manifold seals bypassing pressure internally. Reseal your rotary manifold.
Dan, Field Technician
Satisfied Customers: 5544
Experience: 17+ yrs. shop and field experience with all major brands of heavy equipment, trucks and farm equipment - 1995 WyoTech graduate.
Dan and other Construction and Road Equipment Specialists are ready to help you
Expert:  Dan replied 1 year ago.
Hi Mario did you reseal the rotary manifold? If so and there is still trouble your drive motor will likely be faulty. Check for excessive case drain pressure by removing the case drain line, running a hose into a bucket, pin the track and sprocket to prevent travel, engage travel and if oil comes out under high pressure the drive is bad. It should be low volume of oil. Compare both sides
Customer: replied 1 year ago.
Yes that's what I am thinking of to inspect the LH/RH drive motors but I am also in doubt why both travel motors was defective immediately and is it it possible that there's a problem in the control valve? And the reason I asked you because I believed that 2 heads are better than one and being a mechanical engineer and also service manager to an American and Japanese products it's also my thinking that I can solve it with more suggestion rather than opening right way the system from the unit. Thanks
Expert:  Dan replied 1 year ago.
Hi Mario, As mentioned in my first response rotary manifold seals are the number one cause of travel problems and commonly get misdiagnosed for a failed travel motor. Resealing the manifold is a part of troubleshooting. Also check the relief valve cartridges on the main control valve and check for excessive case drain pressure in the drive motors.