New member/new owner of a komatsu pc138 uslc-8 thats needs help.

Hello All
First time here and first time owner of heavy equipment and a very GREEN operator. I've owned farm tractors and a couple of coal trucks but that the extent of it.
I just purchased a 2008 komatsu pc138uslc-8 with 6800 hours on it. When i first got it to the farm i noticed that when i was backing down any small slope the right track would stop and restart, I thought it was just something i was doing and soon realized that it the machine.
I cant hear and kind of metal on metal,I checked the track adjustment and it has 1.25 inches of slack between the top two rollers, I drained the final drives and the oil looked good to me but i did replace it.
If anyone can help me troubleshoot this problem i would greatly appreacite it.

Are there any alarms on the monitor panel? Do you know how to check for fault codes? Here is a video showing how to get into the diagnostics in the panel.


Slack in the track should be measured with the track frame picked off the ground and measured between the middle bottom roller and the track rail. Here is a video showing basic maintenance for Komatsu excavators. The machines are older the the procedures are close enough to the same.


Does the machine walk straight when you travel up a hill? Are both tracks pulling the same when you try to turn the machine?

Mr. John
Thank you for the videos, the info will be very helpful.I never had any alarms but thanks to you i know how to check the history now. As far as the up hill travel i want to say that it is traveling straight but i will verify next weekend when i get the chance to get back on the machine, Its on my farm and i live 3 hours from it. I have noticed when i try to turn sometimes i felt like it struggled and sometimes it just turns on a dime. I will reply again next Sunday and let you know my discoveries.
Again thank you sooooo munch and if you have any other ideas come to you before i head there next weekend please let me know..