Contaminated hydraulic oil
My crew has a CAT 259D3 (high flow) skid steer that we have to loan out to other crews as needed. Unfortunately, whenever we loan it out, it always seems to come back with issues…
A couple of weeks ago it was dropped off by a crew, sat in our yard for two weeks, and another crew came by the other day to pick it up and borrow it.
I’m pretty religious about my pre-checks before I use our machine, so I was checking the fluids before it was loaded on the trailer, despite the other guy giving me shit and saying he never bothers to do that.
When I checked the sight glass for the hydraulic oil, it was maxed out in the red on the overfill side. I let the guy know I had to do some investigating and that he might not be able to take it with him. He didn’t even know where the sight glass was. 🤦🏻♂️
When we opened the cap for the hydraulic oil reservoir, the oil was a milky pink color. Our mechanic confirmed that the oil was contaminated. The other guy was still wondering if he could take it, and I said hell no.
Our mechanic said it could be water or possibly another incompatible hydraulic oil.
I wanted to see if anyone here has run into something like this before.
Some possibilities I’ve been running through my mind:
-Condensation buildup from temperature fluctuations?
-An issue with the hydraulic reservoir breather allowing moisture in?
-Contamination from a hydraulic attachment that had incompatible oil in it and was previously used on our machine?
-Someone accidentally putting diesel into the hydraulic reservoir? The fuel gauge was at 1/4 tank, and I could have sworn that when the machine was dropped off, the other crew had topped it off with diesel…
The machine had been sitting for about two weeks before I found this, and fortunately I caught it before we started or operated it.
Thoughts?
Edit: Thanks to a commenter I also just realized that our mechanics may be stocking replacement oil that is plant based, ie: CAT Bio HYDO Advanced oil. I do not know whether this skid steer was sold to us from the dealer with the typical petroleum (mineral) based oil, CAT HYDO Advanced 10 or the Bio HYDO.. I know that they cannot be mixed. The HYDO Advanced 10 is listed on the SDS as red, the Bio HYDO is listed as amber. The mechanic said the oil should look clear amber, which indicates they are using the Bio HYDO. I’ll have to ask them what they stock and what the machine was ordered with.