I drained 15 gallons of milky looking hydraulic oil from my backhoe this week. I'm sure there's afew more gallons still in all the hoses and cylinders so I plan to run it and change it again.

Water seems to stay in suspension in it and not settle out like other oils.
I'm wondering if there's a way I can dry it out. Vacuum, heat, filters...

I hate to waste 30+ gallons of expensive hydaraulic oil.

Ideas?

I would think you could carefully heat it and drive the water out of the solution.

Would take quite a bit of energy to heat 30 gallons to 215°F.

Google on removing+water+hydraulic+oil and you'll get some hits. As you suspect, some of the methods involve vacuum, heat, filters...

I don't know if any of them would be practical as a DIY proposition.

15 gallons of new oil cost me over $100. I figure I can heat up 30 gal for less. I'll most likely try to do it 5-10 gals at a time.

I'm thinking a 55 gal drum (since I have one on hand) containing 5-10 gals, heat the bottom and pull a vacuum while heating.
Might crush the drum if I'm not careful.

A 55 gallon drum won't take much of a vacuum prior to collapse. A high vacuum would allow a much lower temperature, but, would necessitate a very strong container. For low vacuum levels, it's not worth the bother.

What's the difference in vapor pressure between hydraulic oil & water? If you know that then you can figure-out how much of a vacuum you'd need. of cours PV=nRT so you have to look at the temp relationship, too.

I am available to make those calculations. My fee is $100.

I suspect I'll get better results if more oil is exposed to dry air. I'll try just heat first.

Hot oil waterfall/film over a hot plate might work best.

Should cost me a little over $100 to build something.

Buy a turkey fryer and do it in 3-4 gal. batches. You can find a cheap one for less than $40 and pick-up a fryer thermometer for less than $10. It doesn't take long at all to heat it up. Almost frighteningly fast.

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1980 300TD-China Blue/Blue MBTex-2nd Owner, 107K (Alt Blau) OBK #15
'06 Chevy Tahoe Z71 (for the wife & 4 kids, current mule) '03 Honda Odyssey (son #1's ride, reluctantly) '99 GMC Suburban (255K+ miles, semi-retired mule) 21' SeaRay Seville (summer escape pod)

I bet if you posted this on the diesel forum, the WVO guys could give you more on the subject than you ever wanted to know.......


I only know I had a guy work on a small backhoe I had once that had essentially the same problem and he flushed out the cylinders with isopropyl alcohol from a pressurized yard sprayer. I always knew that is what you clean the plungers with but he said it also displaced any residual water.

The alcohol won't attack the seals?

Buy new oil. Fluid is so important to the life/operation of hydraulic systems it's better to just bite the bullet and spend the money. All the more so since the ideas you're finding for dewatering are going to cost you close to the same amount. I realize that there is the whole thing about once you construct a dewatering device you'll have it available, it will only be a one time cost, but even still, perhaps it might be best to spend that time and effort making sure that whatever happened to get water into your hydrualic fluid never happens again. That way, you'll never need a ramshackle dewatering device again.

MV

I broke the boom on the thing too soon burying a horse before it would have had a chance to do any attacking, ifn it were so inclined, and had it hauled off.

Thats the equation for ideal gases, not liquids. Actually its

PV=znRT z factor is the gas compressibility.

It is probably forming an emulsion of some sort. You could use an emulsion breaking chemical, I would want to find out how water get in there in the first place. Is it condensation? Maybe filter it out. If it is an emulsion, let it sit, it may settle on its own, depending on the relative densities of the fluids.

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MB-less

Rigged up an old air tank as a flash evaporator. Plan is to pessurize the contaiminated oil, force it thru a filter then heat by passing it across a water 220v htr element running on 110v then out thru a small orifice to flash the water to steam.
Another idea I had was to use an electric griddle. I found a 1500 watt "Presto" unit that has a trough and small drain hole in the front. The plan is to trickle contaiminated oil at the rear of the griddle on a very slight slope to the front. Griddle set to 300f should boil off any water. Dry oil drains out the hole in front. Might be slow and take a few passes. Large surface area exposed this way though.

No plan to re-use the oil in the hoe. Just a challege to get the water out more than anything else. Plus I hate to throw out 30 gallons of $8/gal oil if I can help it. I'll use it in a waste oil htr for the barn/shop.