Diesel In Hydraulic Tank

[camelchop]

FOREMOST - I apologize if this is a redundant inquiry. I did perform a search in this forum and the first few pages didn't yield any hits. Earlier this afternoon, I received a call from a buddy who performed some excavation work related to a pad I am getting ready to pour for a double wide to sit upon. He had left his Case 450CT and headed off to another job. I was using it at my property and broke a track. Unbeknownst to all, the unit had a severely worn idler, we assume causing too much lateral movement/improper tension. Eventually the machine found the weakest spot in the track I guess and it ripped. It gets worse.... Now, after retrieving the machine last week, he has experienced an issue with the relief valves, first starting with the machine lifting a full load in the bucket. He took the unit to a shop and diesel was discovered in the hydraulic tank. I put 21.x hours on the unit and filled it twice IN THE PROPER tank on the right side of the unit. He is a great friend, long history, etc. He isn't pointing fingers, but provided reasonably confident assurance the unit was not exhibiting such performance issues prior to it operating at my property/my use. We are unfolding an investigation, but it is doubtful anyone is going to burst forward and accept responsibility for the error if someone did. I had various parties "helping" (or not) during the span which the machine was present. The shop has switched the forward and reverse dump valves, flushed the system, and replaced the fluid. The service technician advised the machine was "on borrowed time" with the drives and possibly the pump. He advised it is currently operating closer to its normal considering its hours, etc. My questions are: a) Is it inevitable the drives will fail prematurely? Like in dozens of hours, not hundreds, or thousands. The unit has 2,700 hours on it now. b) What symptoms would this machine exhibit during operation after the hydraulic system was contaminated initially? (I don't have a threshold for what its normal would be...I noticed, as did the owner when he retrieved the unit, the area of the hydraulic reservoir where it appeared it had been "belching") Would the mixture foam when agitated? c) Does the Case 450CT come with 10W-30 OEM and what would mixing traditional hydraulic fluid into the system do? Same extent as the diesel? I also have a Ditch With 3500 and asked someone to add hydraulic fluid and am wondering if he topped off the wrong machine. Again, in a direct confrontation it is unlikely I will get any party to admit doing so. And regardless, ultimately it is my responsibility to my friend.

 

[Tazza]

Diesel is still a lubricant, i would like to say that it would not automatically give the machine a set number of hours left. It would really depend on how it was used during that time, if it was really working hard i can see possible wear happening, but if not it may have done no damage at all.
I'd swap the oil out a few times till it smells right and see how it goes.
The lowered lifting power could be that the oil was thinner.

 

[OldMachinist]

Diesel is still a lubricant, i would like to say that it would not automatically give the machine a set number of hours left. It would really depend on how it was used during that time, if it was really working hard i can see possible wear happening, but if not it may have done no damage at all.
I'd swap the oil out a few times till it smells right and see how it goes.
The lowered lifting power could be that the oil was thinner.

How much diesel could they have added? The hydraulic tank would have had to be pretty low in order to get enough in the system to do any real damage with only short usage.

 

[Rodonyomom]

I mix slick diesel in my hydraulic tank in the winter . Makes for smoother operating in cold weather . Learned it from a county state worker that says that's what they do with all there equipment in the winter. So a little Diesel ain't gonna hurt anything

 

[Mustang Guy]

Adding distillate diesel fuel to a hydraulic system for any length of time is a pretty ignorant slack-jawed idea. Yes, they are miscible but the diesel will dilute the paraffinic base stock of the hydraulic oil, and worse, it's anti-wear additives and modifiers, not to mention taking the viscosity to the basement (Have you performed an oil analysis?). If you're going to be operating consistently in sub-zero arctic conditions there are cryogenic hydraulic oils formulated for that purpose - ISO AW 10 and ISO AW 22. ISO AW 23 hydraulic oil has about the same viscosity as SAE 10 motor oil, so if you really feel the need to tinker with viscosity dilute with one of those oils. For me, I use a multi-grade hydraulic oil (ISO AW 32/46/68) in all of my machines, and it works equally well summer and winter.
But y'all do what ya want.