Bobcat 753 hydraulic oil turned milky ........

[inane2]

Good morning all,

Working on my 02' 753. Fan gearbox was leaking and left pintle seal was leaking. New seals, o-rings and a speedy sleeve later and I'm back in business. I already had an engine jig for a 763 so I ended up pulling the motor and fuel tank out and giving this thing a proper cleaning. Years of gunk from those seals leaking and neglect from the previous owner.

Got the motor back in and everything fired right up. Probably put 5 hours on it and when I re-checked the hdy fluid, it's milky, almost like coffee with way too much creamer. Took the breather cap and strainer out of the tank, shined a light down in there and the whole fluid reservoir is like that.

While the bobcat was down, I did: left and right pintle seals and o-rings, new drain case filters on both sides, new fitting on left drive motor (broke while changing drain case filter), new hydraulic filter and I ended up putting right at 5 gallons of hydraulic oil in it. Took about 3.5 gallons to get it up on the stick before I started it and after starting it and cycling everything, I ended up adding about another 1.5 gallons. Using Traveller 10W30 motor oil from Tractor Supply for the hydraulic oil. Every connection was capped off while the motor was out, both on the machine and on the engine. Hydraulics are running fine and everything is quiet. Didn't have any of this milky condition prior to pulling the engine.

I see that air or water are the usual suspects. I don't think water is my problem unless some snuck in during the cleaning process (using an electric pressure washer). I guess I need to drain / refill the reservoir and try to clean this out. Thinking about going to an AW32 or 46 this time around and ditching the 10W30. Any thoughts, suggestions or tips from the pros here on the forum?

 

[Roadworthy]

If you plan to drain it again anyhow find out what the manufacturer recommends for hydraulic fluid - hydraulic fluid or engine oil. Yes, the milky consistency does sound like water in the fluid. You could probably drain off a sample, let it sit for a day or two and see what you get to settle out.

 

[inane2]

Thanks Roadworthy. My owner’s manual calls for 10W30 in the hydraulics but I’ve learned that Bobcat discontinued this practice in 2006.

Cracked open the hyd filter and drained a little out. Starting to think it is water mixed in.

 

[aczlan]

Looks like water to me, I would replace it all.
If you can, I would lift the loader all the way up and curl the bucket fully, then shut the engine off, drain the hydraulic fluid, dump the bucket, then lower the arms (don't put them in float).
That should drain most of the fluid out and leave the loader cylinders filled with air. Then refill the hydraulic tank and cycle the loader up and down a few times to push out the air.

Aaron Z

 

[SSdoxie]

AW 46 is closest match to Bobcat Hydraulic/Hydrostatic fluid, or 32 if 46 is unavailable.

 

[laurencen]

water, does not take much then working machine soon turns it to soup, myself I would flush it with cheap motor oil, when draining ensure all cylinders are at there shortest before dumping then fill with the correct oil as per Bobcat.

given time the water should seperate and would be good for lubrication uses