How to tell if hydraulic oil is fouled

Roment · Apr 22, 2015

I have a 1975 ford 7500 backhoe. Just pulled the hydraulic filter because hydraulics aren't working. Filter held oil even when removed from housing so I am sure it needs replaced.

The question is what should the fluid look like?
Appearance is milky yellow. First thought was it has water in it but I let the tractor sit a week and there doesn't appear to be any oil/water separation in the hydraulic tank.

Any advice will be greatly appreciated.

Tim PloughNman Daley RIP · Apr 22, 2015

Milky color is always an indication of water contaminated oil. Not sure if you'll see any separation.

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showcrop · Apr 22, 2015

my experience with various machines is that the water gets absorbed into the oil and very little will separate out. When you drain it try to get it good and hot first and let it drain over night.

Sean in PA · Apr 22, 2015

It depends on what oil was in it as to what additives it might have to allow it to keep water in suspension, but most of them these days have some sort of additives that will tend to keep it from separating, at least for a few days.

Mike(NEOhio) · Apr 22, 2015

This is gear lube, not hydraulic, drained after sitting a long time. The water didn't separate.

JF in MI · Apr 22, 2015

I had the same thing. It takes a long time for water to separate. Before putting mine away for the winter I drained all the
fluid into 5 gallon pails and let it sit for about 3 months. All the water settled to the bottom and either froze into a block
or the oil could be poured off the top. Poured it back into the hoe and now runs clear.

Ecnerwal · Apr 22, 2015

To some extent, if it's not in a new sealed container, it's fouled.

Aside from JF's technique for next fall/winter, the other good way to get water out is to use the heck out of the hoe/hydraulic system and get the fluid hot - the water will leave by the vent, as vapor.

Any hobby hoe will have water in the fluid shortly after it's changed, unless it's in a desert climate. They don't get used hard enough, long enough, often enough to stay clear, usually.

souNdguy · Apr 22, 2015

if it's contaminated and emulsified.. i'd dump in some atf, alcohol and diesel, run it till warm, then drain..

RodinNS · Apr 22, 2015

The only way to get water from emulsified hydraulic oil is to boil it out... so in other words, drain it and get new oil. You can try rinsing with diesel fuel, etc... but ultimately you're just going to end up doing a few changes. The best thing you can do is get the machine and oil HOT. Work it. Hard. The water will eventually evaporate.

Rod

Roment · Apr 22, 2015

Mike,

My Hydro fluid looks exactly like your picture....guess its time to drain it.

Roment · Apr 22, 2015

(quoted from post at 08:07:54 04/22/15)
Any hobby hoe will have water in the fluid shortly after it's changed, unless it's in a desert climate. They don't get used hard enough, long enough, often enough to stay clear, usually.

Since this is a hobby hoe...how much damage will I cause running it with the water in the oil? What are the repercussions?

I can get it hot and drain it but if its just going to be the same way in 90 days, is there any use or do I just change the filter regularly and hope for the best?

showcrop · Apr 22, 2015

(quoted from post at 13:16:33 04/22/15)

(quoted from post at 08:07:54 04/22/15)
Any hobby hoe will have water in the fluid shortly after it's changed, unless it's in a desert climate. They don't get used hard enough, long enough, often enough to stay clear, usually.

Click to expand...

Since this is a hobby hoe...how much damage will I cause running it with the water in the oil? What are the repercussions?

I can get it hot and drain it but if its just going to be the same way in 90 days, is there any use or do I just change the filter regularly and hope for the best?

Roment, I have some experience with this. I have an old forklift that always had milky crankcase oil. I rarely used it long enough to heat it up, but a friend in the forklift business told me not to worry about it. 25 years later it shows no ill effects of oil changes at only 500 hour intervals. One of my fairly late model farm tractors never had milky oil but suffered catastrophic transmission and hydraulic pump failures in consecutive years due to wear that they told me happened from particles in the oil causing seals to wear during the time that the previous owner had it. I will draw the conclusion that oil contaminated with water can cause damage to bearings due to lack of fluid oil film but I don't see it hurting seals. So even though your hydraulic system has bearings in the pump, your main exposure is in seals and I don't believe that your risk is that great.

Roment · Apr 24, 2015

Showcrop,
I appreciate your reply and experience. I am going to change the filter then go dig with it and see how hot I can get the oil....my wife wants a koi pond so I have the project.

Geo-TH,In · Apr 26, 2015

The problem with a backhoe is the cylinders and hoses hold a lot of oil. So draining it
will leave a gallon or two or three behind. It will require many oil changes to get most
all of the bad oil out.

How to tell if hydraulic oil is fouled

Roment

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Tim PloughNman Daley RIP

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showcrop

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Sean in PA

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Mike(NEOhio)

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JF in MI

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Ecnerwal

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souNdguy

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RodinNS

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Roment

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Roment

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showcrop

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Roment

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Geo-TH,In

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