Seperating water from hydraulic fluid

[Corley5]

  I tried it in an attempt to keep the Greisen valve body on my Tree Farmer forwarder from freezing up.  It didn't make any difference.  The machine had to be started and allowed to warm up for the valve to thaw.  You could watch the snow melt on the oil line going into the valve body and tell when it was going to work ;D  It was that way when I sold it.
  I did use it in another machine when the reservoir cap was left off and the fluid got milky.  The fluid cleared up but it may have been from heat in the system.  If it wasn't an old fashioned gear pump I'd have changed the oil ;) ;D  I've got a couple cans on the shelf in garage.  They've been there a couple years now. 

[Trahlin]

New oil, new clean up filters (short term), and change filters after a days work.  Most filters are have a cellulose (paper) media.  Water destroys the filter.  Use the clean up filters to trap the remaining water from the system.  Remember water and steel don't play well together.  Hydraulics are based on tight tolerances, and finely machined metal surfaces.  Pitted metal surfaces tear up seals and o rings.  It is a never ending cycle, if you choose the cheap route.  It hurts the wallet now, but will play out better in the long run.

This advice is based upon my career as a farm and industrial machinery dealer.  Pay now, or pay much bigger later.  I feel your pain!

[HuckFin]

Where I live we get a lot of moisture in the air during the winter so when I had my Case 580B (parked outside) I found out that if I drained the water off at the hydraulic tank drain plug before starting it the first time in the spring the milky oil problem went away.

[mike_belben]

Any oil using an organic plant based stock is gonna be hygrosopic, itll absorb the water particles that it comes in contact with through condensate in vented crankcases and tanks etc. 

The easiest removal is by heat and vaccuum.  I have done a few thousand gallons of waste vegetable oil that could have had fully seperated or emulsified water.  Settling time is your friend, as its very inneficient to try to remove large quatities of water by decanting.   Let sit in the sun for a time and without any disturbing of the vessel, open cap and draw the cleanest oil off the top with a suction tube rig.  Stop way before you get near the bottom as itll draw a vein of trash up from inches below the suction tube. 

Really filthy stuff can be settled in another tank or go into the decanter.  A very simple rig would be a 55gal drum on blocks over some coals.  There needs to be a valve welded into the bottom to let air in, and a hose out the top to a vaccuum pump.  You heat it up a while under vacuum.  After an hour or so there will be moisture in the headspace of the drum.  Open the bottom air valve and the vacuum pump will let it burble in while suctiom that moisture out the top.  Youll want to make a condensor jar on the the suction line so it doesnt all go into the vacuum pump oil.  A pickle jar inside a bucket of water works great.  Dont fill your drum past 2/3s or youll be sucking up oil too.  Also welding some verticle angle iron, rebar or flat strip from bottom to top will help keep the drum from caving in, it doesnt take much.

If you added a gear pump circulator loop through a bank of filters in parallel with sequentially finer stages youd have you a reconditioning rig.

40 gallons of perfectly clean looking oil will typically have a beer can worth of water dissolved into it fyi. 

[Gearbox]

Didn't think of this until today when I was trying to get all the wet oil out of my skidder . Jacked the cylinders up to top and down to bottom and pumped all the oil out of the trans. then put in 2 gallon and pumped that out . I use the spoon test . Take a small teaspoon put a little oil in it and heat it with a Bic . Any water trapped in the oil will boil off as bubbles and can be seen . Try it next time you think you may have wet oil .

[mike_belben]

Yeah, Lotta people call that hot pan test or hpt.  Its a good quick check for dissolved water.   bit more accurate if you smear some oil on the spoon or pan or in my case scrap of sheetmetal, then heat till it just starts to smoke a few whisps.  Now splash on a cap full of oil and look for the bubbles. 

If you start heating oil direct the oil itself will start to boil eventually and you can think its water.  The trick is to be above 212 yet below like 400 or so

[Randy88]

Really old thread, but the best way to determine the amount of water in any oil is to have it sampled and run the tests in a lab, they'll give the percentage of water in the oil along with all the wear metals and silica [dirt] and micro minerals in the oil, gives an overall condition report of my machine's internal shape of the components.     

As for settling out the water, most hydraulic oil won't release all the water, the additives in the oil with encapsulate the water and not release it.     

There are water filter carts out there that will take a large portion of water out of the oil, but the filters are not cheap, and you need large volumes of oil to justify the cart and filter setup costs, most implements can't justify the cost of those units, let alone any individual.     

My advice is to keep the backhoe inside under cover whenever possible, change oil often and put a set of filters on the system, if for nothing else, to clean out wear metals and clean the oil as it flows through the system.