Purging hydraulic system (water in oil)

I own a semi trailer with a hydraulic beavertail. It has several
hydraulic cylinders and a hydraulic winch.
We run it using a hydraulic unit that we made with a Honda engine that
replaced the electric motor that was on the unit originally.
It always worked great.
The oil has developed a "water in oil" condition, and with cold
weather the ice crystals blocked the inlet and everything stopped
working. I suspect that this is so because the trailer's hydraulics
was full of water from the beginning.
We drained the oil today and I have plenty of new oil to put
in. However, I want to drain the old bad oil from all cylinders.
My plan is to remove the hydraulic filter that is on the return line
to the tank, connect a pipe to it that would drain into a bucket. Then
we would put new oil in the tank, and operate all cylinders and motors
until only clear oil comes out of the return line.
Would that give me a decent enough purge?
Anything I am missing?
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Open center or closed center hydraulics? I presume open center on a small unit like that in which case you get return flow when the pump is operating regardless of operating the cylinders, so you'll go through a lot of fluid by the time you cycle all the cylinders.
They make "tank tampons" that you can hang in a diesel fuel tank which absorb water, but not diesel fuel. Possibly they might be able to be used in your hydraulic oil to absorb water in the tank.
Reply to
Pete C.
Good question. I am not sure. But there is a number of valves that can be actuated to operate this beavertail. I do not think that they would work together if they were open center.
Reply to
Together or one at a time? If your power unit is a little gas engine and a basic gear pump it's most likely open center, more common and cheaper. Closed center uses variable displacement pumps and is used on large construction equipment allowing simultaneous operation of functions.
Reply to
Pete C.
You didn't purge it from the start, so it wouldn't contaminate your hydraulic pump? I thought that was -everybody's- first action, in case it contains water/swarf from a bad old pump.
I've seen a couple cylinders with drain ports, but I doubt that's the norm. You're going to go through several 5gal buckets of hyd oil in the process, but if you can't drain 'em, cycling is the only other way I know of. Then keep a tampon in there to sop up what you miss.
Reply to
Larry Jaques
And I bet that happened when you had trucked out to an auction site and had a fork lift loaded and waiting for you to lower the trailer. And the window for pick-up was about to close. My sympathies. Bob
Reply to
Bob Engelhardt
one at a time, or together.
The pump is variablle displacement. It is an expensive pump. It is not from some kind of a toy like log splitter. i
Reply to
Not a direct answer to your question, but I think the oil they sell for snowplows is supposed to have some chemicals that absorb water. Maybe, once you are done doing whatever it is you do end up doing, that kind of hydraulic oil would be the way to go.
Pete Stanaitis ---------------
Reply to
Pete S
Well, if it is a closed center system that will help by only having return flow when you are actuating the cylinders and whatnot. Less fluid needed and less contaminated fluid to dispose of.
Reply to
Pete C.

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