WA 380-6 hydraulic oil overtemp even at an idle.

[shermanh]

HI First post ever. I am having issues with our wa380. Is overheating the hydraulic oil very easily after about an hour of run time. I did my first checks and changed hydraulic filter, Checked strainer, and Pressure washed the cooler out real good. I also checked fan speed and pressure, it checked out in spec. I hooked up pressure guage to main control valve assembly to check main pump pressure and function. System pressure check out good to relief..
So while running and going through functions all of the sudden noticed that the main pump would not destroke and you can hear going through one of the relief valves. (Which i think is my overheat problem). If I then manually send a fuction to main system relief it clears and returns to normal. But as the hydraulics get warmer it happens sooner and sooner.
I pulled the main relief and found no damage. Both springs in one piece. PPC pressure is in spec.

This machine has about 12k hours on it.

 

[coalrulz]

Shermanh, is you WA380 a -5, -6, -7, -8? Serial number would be handy as well.

 

[shermanh]

Shermanh, is you WA380 a -5, -6, -7, -8? Serial number would be handy as well.

This is a -6. SER number is A53046

 

[shermanh]

This is a -6. SER number is A53046

Sorry that serial number is A53065

 

[coalrulz]

Believe the key element you uncovered in your testing is the fact that you have noticed pressure in the work equipment system with out moving a work equipment function. This hydraulic system is what Komatsu calls CLSS (Closed center Load Sensing System) where the load sense pressure generated at the work equipment spool (based on load on work equipment cylinder) is taken back to hydraulic pump to act on work equipment pump servo to increase pump displacement. Have seen where a sticking servo spool will hold pump "in stroke" without moving a work equipment function, leading to the hydraulics overheating as you have described.

 

[shermanh]

That seems to be the direction I was headed for. It doesnt matter which function I use, weather bucket or boom it will stay stroked up. And it does this real quick and fast the warmer the oil is. I will update after more testing and a solution is figured out. Thank you for your reply.

 

[GKPHMECHANIC]

That seems to be the direction I was headed for. It doesnt matter which function I use, weather bucket or boom it will stay stroked up. And it does this real quick and fast the warmer the oil is. I will update after more testing and a solution is figured out. Thank you for your reply.

Did you ever find anything on this?

 

[shermanh]

I am having to have another company look at this. Im stumped. I had the local Komatsu dealer come out and they made a suggestion but didnt know for sure.. The tech suggested a new unloader valve. I replaced that and it did not cure the problem. Meanwhile after getting a $3200 bill Im done with them. Pretty pissed they said they would send the tech out again and after a month and not returning my phone calls I have decided to go another direction.. I just transported the machine in and will report after the other companies findings.

 

[Khuff]

Hi there
Does anyone have a solution to this problem? We have the exact same problem with our 380-6 with a close serial # as well. It appears this may be a common problem with these units.