milky hydraulic oil

[tylermckee]

Long story short we had our dealer out to CHANGE the hyd. oil in an excavator, and they didnt change it, they ran the old oil through a filter system they have and pumped it back into the machine. 1 day later we notice that the oil is very milky, looks like a brown/green milk. dealer so far wont actually come out and say that they f***** up, but they sent a guy out to 'flush' the system today and after an hour of use the oil looks almost as bad as it did. obviosly they didnt get everything out of the system, but what do they actually have to do to remove ALL of the contaminated oil from the machine. We have oil samples that are goining out for analysis tomorrow so we will be able to get a rough number of what and how much mater or whatever got in the system.

-What does it take to remove all the bad oil?
-what kind of long term damage can result from this? probably ran the machine ~10 hours, 5 of those hours with a breaker on.

[Kgmz]

What did they do to flush the system?


It is very hard to get the water out of hydraulic fluid. Sometimes can be removed with water absorbing filters in the filter cart. But you have to do it over and over again and keep changing the filters because they can't capture all that much water. Then you run the machine, cycling everything to get the contaminated fluid into the reservoir that was in the lines, cylinders, pump, etc. And then run all the fluid in the reservoir all over again, and again.

But the best thing is to drain all the oil out and start all over again with new fluid in the reservoir and the running everything to get what you could not drain into the reservoir and then running it through the filter cart. And the very best thing is to drain all the fluid out and then flush the system with a very light viscosity fluid and then drain and dump the flushing fluid. Then fill with your normal fluid.


I am wondering how the water got into your fluid. Could be that their filter cart was contaminated somehow, old filters with water in them, etc. Or it could be that the water was already in your system sitting in the bottom of the reservoir, and that when they ran the fluid through the cart it got emulsified into the oil and they did not have a water absorbing filter in the cart.


Depending on how much equipment a company has I recommend that most get their own filter cart. We bought our Parker filter cart a few years ago when our old excavators oil got contaminated with water. Still not sure how it happened, but I think the water was from condensation in the tank as it had been sitting unused for quite awhile. When I found out the cost to clean the fluid and system from the dealer, I decided it was better to invest the money in something I could use over and over. And since we own over 10 pieces of equipment that have hydraulic systems it has been well worth the investment.

Forgot to add we paid about $1100 for our cart, and I see now that they are selling for around $1400 now.

[John C.]

At this point the only way to get it out is to dump is all. That means dumping the oil from the bottom of the reservoir, taking the suction hose from the pump and draining that out and taking as many hoses loose and flushing them out as possible. You will still need to refill and run the system and then flush again to clear the cylinders, motors and coolers unless you go for a total teardown. I've done it both ways. If there is no metal I might just flush and take my chances. It may also depend on what the stuff actually is. It might have come from marine or aircraft use and not be compatible with your machine's system.

I would never run a high performance hydraulic system on any oils that are not specifically recommended by the manufacturer.

I take it that you caught the issue before running the machine for much time. Taking the oil samples is great because you now have an actionable claim against the dealer that did the deed. Push for everything you can and get an attorney on retainer for possible legal action. The fact that the dealer went for another flush instead of doing what was proper indicates their idea of the solution is somewhat less than what may be needed.

[rino1494]

Our one dozer had milky hyd fluid. We drained the tank and disconnected the hose on each cylinder one by one and we hooked up a air chuck to it and blew back through the tank. Changed the filter, filled up with fresh oil and now the sight glass on the hyd tank is crystal clear.

[tylermckee]

They drained our machines fliud into a 'clean' oil drum, then ran it through their filter cart into the machines tank. they have also ran 2 other machines oil through their filter after they did ours, and they say they didnt have the same problem.I think they had something in the drum, another kind of oil or water. we caught it within 8-10 hours.

When they came back to fix it they did 'flush' the system, but i dont know exactly what his procedure was.

As of now they have our machine at their shop, not sure what their plan of attack is yet. they seem to think something with the machine is causing the issue, but i'm having a hard time believing that when the oil that was in the system had 3,000 hours on it and looked great.

[mrnick777]

we had a bobcat withthe same problem and flushed it through the aux ports

[Catpower]

About 30 something years ago had that problem when exchanging hydraulic equipment with a friend. Was told years later that when you mix John Deere hyd oil with ( Ford hyd oil) it will turm milky! Is this still the same when mixing hyd oils? It amazes me that places try to say we didn't do anything wrong. Why they would let it go out the door or say that they are finished with it when they aren't? What do they figure that we aren't going to notice it?

[Johnsoils]

A PAO synthetic hydraulic fluid will not emulsify typically. I've had problems with conventional oils in large air compressors and hydraulic systems. After switching to AMSOIL, I've been able to leave the machine down overnight and drain the condensate/water off the bottom of the crankcase or tank.

Another good maintenance practice is to use a desicant breather on your hydraulic system to filter out both contaminates and moisture. Moisture enters the hydraulic system through open reservior breathers or vents. We had a lot of problems with industrial gear boxes here in NE Iowa in the humid summer months. Since installing the desicant breathers and AMSOIL, no more moisture or maintenance issues. Please feel free to contact me if you need vendor information on the desicant breathers or AMSOIL.

[Durette]

There's no replacement for actually CHANGING the fluid. Your oil can get coked (partially burnt) because these systems can run up to 200 F. Absorption of air and contamination with water only make matters worse. Petroleum oils form acids when contaminated like this, and it forms acids which can eat your seals, valves, and metal parts.

Yeah, it costs a lot to change the fluid, but your seals and system will thank you.

[Johnsoils]

I agree that if your fluid is contaminated and/or oil analysis shows that it needs changed that this is the only option. Synthetic hydraulic fluids will stand up to temperatures way above 200 F. If you want to see some spec sheets on synthetic hydraulic fluids let me know. I would be glad to send them to you. Here in Iowa a newer problem with hydraulic systems over heating is the new air planters that the farmers use to plant corn and soybeans. These planters are huge, 24-rows or more. The air blower motor is powered by the hydraulic system and man do they get hot. Several of the farmers have switched to AMSOIL synthetic 5W-30 tractor hydraulic/transmission oil and dramatically dropped their hydraulic system temps. They are also able to run the fluid longer, as it is not breaking down or coking under the extreme operating conditions. Also, AMSOIL uses a full-synthetic base stocks, the best in the industry. This higher TBN base stock has no parrifin, sulfur or nitrogen molecules in it when it's new. These contaminates are common in new conventional petrolium oil, so when you add heat and moisture you have acid formation right off the bat. AMSOIL's full synthetic oils helps combat acid formation. Each AMSOIL product is formulated for a specific application and engineered for peak performance, reduced wear and extended drain intervals.

The AMSOIL ATF was tested to 500 F and it would not give up. Finally the third party testing service called of the test. If your having short oil life caused by high operating temperatures and acid formation. I'm sure that AMSOIL synthetics could help you out. See my web site (**************.com) for more information on the products and data sheets, or drop me an email and I'll get the information to you, or call you. Providing knowledge and documentation on AMSOIL product performance is what I like to pass on to folks. I'm here to help if people are having problems, or just what some information to gain some knowledge on synthetics, greases, or filtration. If it turns and burns, I'm interested. Thanks, John

[Durette]

I agree that if your fluid is contaminated and/or oil analysis shows that it needs changed that this is the only option. Synthetic hydraulic fluids will stand up to temperatures way above 200 F. If you want to see some spec sheets on synthetic hydraulic fluids let me know. I would be glad to send them to you. Here in Iowa a newer problem with hydraulic systems over heating is the new air planters that the farmers use to plant corn and soybeans. These planters are huge, 24-rows or more. The air blower motor is powered by the hydraulic system and man do they get hot. Several of the farmers have switched to AMSOIL synthetic 5W-30 tractor hydraulic/transmission oil and dramatically dropped their hydraulic system temps. They are also able to run the fluid longer, as it is not breaking down or coking under the extreme operating conditions. Also, AMSOIL uses a full-synthetic base stocks, the best in the industry. This higher TBN base stock has no parrifin, sulfur or nitrogen molecules in it when it's new. These contaminates are common in new conventional petrolium oil, so when you add heat and moisture you have acid formation right off the bat. AMSOIL's full synthetic oils helps combat acid formation. Each AMSOIL product is formulated for a specific application and engineered for peak performance, reduced wear and extended drain intervals.

The AMSOIL ATF was tested to 500 F and it would not give up. Finally the third party testing service called of the test. If your having short oil life caused by high operating temperatures and acid formation. I'm sure that AMSOIL synthetics could help you out. See my web site (**************.com) for more information on the products and data sheets, or drop me an email and I'll get the information to you, or call you. Providing knowledge and documentation on AMSOIL product performance is what I like to pass on to folks. I'm here to help if people are having problems, or just what some information to gain some knowledge on synthetics, greases, or filtration. If it turns and burns, I'm interested. Thanks, John

I'll agree AMSOIL is the best there is. I use their TSO 0w30 in my car. I used to work at NAPA, and I sold stuff from their whole line. For a while I actually bought the stuff directly from their distribution center in Orlando. Unfortunately, not everyone uses good synthetic fluids. All people see is the short term benefit of using cheap dinosaur juice, and they don't sit down and do the math. Good synthetics offer longer equipment life and longer change intervals; you'd be stupid to do anything else.

[sea_goin_dude]

Have had milky hydraulic fluid on industrial equipment I've worked on over the years. Some companies do not care!!!!! Drain some of the oil into a clear plastic bottle like a two liter or smaller for small system. Let it settle until it all separates. Entrapped air will also add to a milky appearance. If you do flush / drain your system remember that there are many dead end places in the system where the oil may not circulate once it gets there. Like some cylinders. Only way to clear them is to loosen the hoses and drain all the fluid out.
A lot of moisture enters your system by the oil and tank cooling off causing it to draw in air as the oil cools which brings moisture along with it. If the system can sit for several days, drain some oil off the bottom of the reservior, even if you have to siphon it off to see if you have much water at the bottom. After many hours of running this air. water. oil mix, it does take a while for the water and air to settle out. The water will gradually make it's way to the bottom of the tank and the air wil float out to the top. The bottle of your sample will give you a good idea of any real problem you might have.

[fast_st]

I've never had to deal with a massive hydraulic system but had a 10 gallon system get drenched with water, drained it and seperated it. After filtering it still looked milky so I had it in a steel barrel and carefully heated it to 220f and let it vapor off for a couple hours. Seemed to become crystal clear, let it cool and put it back in. Went on the turkey fryer idea, nice slow smooth heating.

[Nige]

I've never had to deal with a massive hydraulic system but had a 10 gallon system get drenched with water, drained it and seperated it. After filtering it still looked milky so I had it in a steel barrel and carefully heated it to 220f and let it vapor off for a couple hours. Seemed to become crystal clear, let it cool and put it back in. Went on the turkey fryer idea, nice slow smooth heating.

My 2 cents worth .........

1. First off, all mineral-based hydraulic oils are hygroscopic. That means they have a tendency to attract water, just like brake fluid only not quite as bad.

2. Water can be present mixed in hydraulic oil in 3 distinct forms.
a) Dissolved - you can't see this.
b) Separated - what sits in the bottom of the tank (if any).
c) Emulsified - the milky colour you can see.

3. The additive package in the oil is designed to work on water particles in the oil in 2 of the 3 cases above.
a) Part of the package assists in the absorption of water into the oil - (dissolved).
b) Another part of the package is designed to help small water particles coalesce and become so large that they fall out of the oil to the bottom of the tank - (separated).

4. The fact that the oil is milky in a hydraulic system would suggest that the additive package designed to assist in treating water (see above) has depleted to such an extent that it can no longer cope and so the water is neither dissolved nor falls out of the oil and so it mixes to form the milky emulsion you can clearly see.

5. Typically in the case of an emulsified oil you might have in the range of 1000-5000ppm (parts/million) of water actually dissolved in the oil, & a similar amount in emulsion.

6. Careful heating will no doubt drive off the visible water and return the oil to a clear bright colour again, but you are not doing anything about the dissolved water in the oil. The additive has chemically combined with it and nothing you can do will "un-combine" the water & oil mixture.

7. As per my example in 5 above by heating you have only driven off half the water anyway.

8. The critical part. If the additive package in the oil designed to treat water has depleted to a point where it no longer works then what about all the other additives present in the oil designed to prevent corrosion, foaming, anti-wear, etc, are they more than likely not depleted also ..?

Hope this might shed a bit more light on the subject.

[HeavyMan]

My 2 cents worth .........

1. First off, all mineral-based hydraulic oils are hygroscopic. That means they have a tendency to attract water, just like brake fluid only not quite as bad.

2. Water can be present mixed in hydraulic oil in 3 distinct forms.
a) Dissolved - you can't see this.
b) Separated - what sits in the bottom of the tank (if any).
c) Emulsified - the milky colour you can see.

3. The additive package in the oil is designed to work on water particles in the oil in 2 of the 3 cases above.
a) Part of the package assists in the absorption of water into the oil - (dissolved).
b) Another part of the package is designed to help small water particles coalesce and become so large that they fall out of the oil to the bottom of the tank - (separated).

4. The fact that the oil is milky in a hydraulic system would suggest that the additive package designed to assist in treating water (see above) has depleted to such an extent that it can no longer cope and so the water is neither dissolved nor falls out of the oil and so it mixes to form the milky emulsion you can clearly see.

5. Typically in the case of an emulsified oil you might have in the range of 1000-5000ppm (parts/million) of water actually dissolved in the oil, & a similar amount in emulsion.

6. Careful heating will no doubt drive off the visible water and return the oil to a clear bright colour again, but you are not doing anything about the dissolved water in the oil. The additive has chemically combined with it and nothing you can do will "un-combine" the water & oil mixture.

7. As per my example in 5 above by heating you have only driven off half the water anyway.

8. The critical part. If the additive package in the oil designed to treat water has depleted to a point where it no longer works then what about all the other additives present in the oil designed to prevent corrosion, foaming, anti-wear, etc, are they more than likely not depleted also ..?

Hope this might shed a bit more light on the subject.

Dealing with water in hydraulic fluid



If you have worked with hydraulic equipment for any length of time, it's likely that you've come across a hydraulic system with cloudy oil. Oil becomes cloudy when it is contaminated with water above its saturation level. The saturation level is the amount of water that can dissolve in the oil's molecular chemistry and is typically 200 - 300 ppm at 68°F (20°C) for mineral hydraulic oil. Note that if hydraulic oil is cloudy it indicates that a minimum of 200 - 300 ppm of water is present. I recently audited a hydraulic system with cloudy oil that was found to contain greater than 1% (10,000 ppm) water.

Why is water in hydraulic fluid bad?

Water in hydraulic fluid:

Depletes some additives and reacts with others to form corrosive by-products which attack some metals.
Reduces lubricant film-strength, which leaves critical surfaces vulnerable to wear and corrosion.
Reduces filterability and clogs filters.
Increases air entrainment ability.
Increases the likelihood of cavitation occurring.
How much water is too much?

A number of factors need to be considered when selecting water contamination targets, including the type of hydraulic system and reliability objectives for the equipment. It's always wise to control water contamination at the lowest levels that can reasonably be achieved, ideally below the oil's saturation point at operating temperature.

Water removal methods

Methods for removing free (unstable suspension) and emulsified (stable suspension) water include:

polymeric filters;
vacuum distillation; and
headspace dehumidification.
Vacuum distillation and headspace dehumidification also remove dissolved water.
Polymeric filters - These look like conventional particulate filters, however the media is impregnated with a super-absorbent polymer. Water causes the polymer to swell, which traps the water within the media. Polymeric filters are best suited for removing small volumes of water and/or maintaining water contamination within pre-determined limits.

Vacuum distillation - This technique employs a combination of heat and vacuum. At 25 inches Hg, water boils at 133°F (56°C). This enables water to be removed at a temperature that does not damage the oil or its additives.

Headspace dehumidification - This method involves circulating and dehumidifying air from the reservoir headspace. Water in the oil migrates to the dry air in the headspace and is eventually removed by the dehumidifier.

In the case of small systems with high levels of water contamination, changing the oil may be more cost-effective than using any of the above methods of water removal.

Prevention is better than cure

Like all other forms of contamination, preventing water ingress is cheaper than removing it from the oil. A major point of water ingression is through the reservoir headspace. Many hydraulic system reservoirs are fitted with breather caps that allow moisture (and particles) to enter the reservoir as the fluid volume changes through either thermal expansion and contraction, or the actuation of cylinders.

Replacing the standard breather cap with a hygroscopic breather will eliminate the ingression of moisture and particles through the reservoir's vent. These breathers combine a woven-polyester media that filters particles as small as 3 microns, with silica gel desiccant to remove water vapor from incoming air. The result is relative humidity levels within the reservoir headspace that make condensation unlikely, therefore reducing water contamination of the oil.
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