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Thread: Moisture in Hydraulic Oil
07-23-2005, 01:52 PM #1
The hydraulic oil in my John Deere tractor is contaminated with moisture. I've heard that this isn't a problem for tractors that are worked hard and often enough to warm the oil and keep the moisture out. Mine doesn't get used often enough.
So, I was thinking of draining the oil and warming a gallon at a time in a crock pot to 220F and see if I can remove the moisture. Has anybody tried this? Does it work?
Are there better ways to remove the moisture?
Yes, I'm a cheap skate and I don't want to buy another $100 worth of oil if I don't have to.
07-23-2005, 02:10 PM #2
Hydraulic oil is not that expensive, but if you want to salvage the oil just drain it in a bucket and let it set for a few days. The water will settle to the bottom and you can reuse it. Warming the oil to 220 degrees is definitely a bad idea. The source of the water is probably a poor seal around the gearshift, so you need to fix that. Your tractor is left outside right? If you can’t afford oil then you will definitely not be able to afford transmission and hydraulic failure.
07-23-2005, 02:11 PM #3
I wonder if a little moisure in the hyd oil even hurts anything. My tractor is an 86' model. I only changed hyd oil once since then and that was because I damaged the hyd filter on a log. I bet if you used that tractor for a 8hr day that moisture would be gone.
07-23-2005, 02:51 PM #4
Equipment like this will get water in the oil without having any place for water to "leak" into the system. The oil is somewhat hygroscopic (attracts water, similar to brake fluid) and relies on heat buildup from hard use to keep the moisture driven out. Once the oil becomes milky looking, you can let it sit for months and the water will not fully separate. Some will separate, but unless the container is tightly sealed, the oil will continue to pick up additional atmospheric moisture primarily due to temperature changes. The one gallon at a time routine in a crock pot would work, and there's no harm done to the oil by heating it, but it would be a real PITA doing it a gallon at a time if the system has much capacity. You can buy immersion type thermostatically controlled heaters on Ebay on a regular basis, often brand new, for less than $50. If you weld a pipe coupling into a 30 or 55 gallon drum, screw in one of these heaters, and wrap the drum with insulation, you'll have a perfect hydraulic oil "dryer". A drum with a removable top works best because it lets the moisture disperse into the air more easily. A closed top drum will tend to let the moisture condense on the inside of the drum top and drip back into the oil.
Regarding the question of whether or not the moisture is harmful, most manufacturers of hydraulic equipment will tell you that, aside from materials or workmanship failures, roughly 90% of all hydraulic component failures are due to moisture in the oil.
My dad was in the crane business for 34 years. During the time when most concrete was poured with a crane and bucket he had almost zero hydraulic problems with the cranes because pouring concrete works a crane hard and keeps the oil hot. Most all the cranes would pour concrete for a full day at least once every couple weeks, and the oil was always clear as a bell. As concrete placement moved more toward pumping, there was little opportunity to do any type work that would load the machine in a similar manner. Problems became much more frequent, and were water related almost every time. We started changing and drying the oil via the method outlined above on a regular basis years ago, and it took care of most of those problems. Some of the oil was probably close to 20 years old, but any time we ever sent samples off for analysis, we never got a report back indicating the oil was "worn out". We kept a couple hundred gallons (enough to change the oil in our largest machine) dried and in drums. When changing the oil, we would pump the old stuff out and put in the dried oil, so we could then dry out the removed oil without keeping a machine down. Over the years we probably saved over $50,000 in oil that would have otherwise been thrown away due to moisture contamination.
07-23-2005, 02:57 PM #5
if the tractor has a hydrualic oil cooler ..then i would blank some of it off withg silver foil or something.
all the best.mark
07-23-2005, 03:21 PM #6
You don't say which tractor you have. The newer ones are much fussier about water than the older ones. Hydrostat systems are the fussiest.
In a hydrostat system, 2% water will reduce the life of the system by 95%. This can be a problem when equipment with hydraulic wheel motors gets stuck in water/mud, and is then shut off while waiting for something to pull it out. The cold water cools the motor, and sucks moisture past the seals.
The factory probably recommends oil changes about every 3000 hours or 5 years (have to know what it is to check the book). New oil is much cheaper than any repairs. Green painted iron sells for $10.00 per pound for simple stuff you can make yourself, to $50.00-$100.00 per pound for complicated stuff like hydraulic system parts.
As for sources of contamination, don't forget attachments with remote mounted hydraulic equipment. These removable hydraulic attachments can make troubleshooting the source of contaminants a real pain.
07-23-2005, 05:28 PM #7
Thanks for your replies.
My tractor is a JD 1520-gas. I've heard these --20 series tractors were more prone to water contamination than others.
I've also known that hydraulic oil is somewhat hydroscopic, so it doesn't even have to sit outside to become contaminated. Unfortunately, my tractor does sit outside, which certainly doesn't help matters any. An addition to the shop this fall should remedy that situation.
A couple years ago, I filled a quart mason jar with milky oil and let it sit for months. About half of it became clear, while the lower half remained milky. I don't believe it would ever settle out.
My tractor has approximately 10 gallons of hydraulic oil capacity. A couple years ago, I replaced the oil, but not all of the old stuff drained out and the new stuff was quickly contaminated, diluted contamination, of course.
That's why I've been thinking of ways to decontaminate what would otherwise be perfectly good oil. Needless waste bothers me more than spending money.
07-23-2005, 05:36 PM #8
You could heat the oil tank from within .
you could put in there a little radiator running off the the main coolant supply.
A heater matrix would do it.
and the oil would only get as hot as the main engine about 88 degrees cent max.
all the best.mark
07-23-2005, 05:59 PM #9
Don't they have "magnet heaters" for large diesel trucks in the winter...ala stick the magnet to the crankcase/oil sump and plug in?
Granted that might get the shop hot but it may or may not help.
Part of the problem with adding heat as I mention is what Metalmuncher suggested...that the moisture will just migrate to a cool part of the enclosed system and condense there...leaving the oil, but staying in a housing or cavity and collecting there. A small amount of airflow is needed to remove the "humidity" and that's hard to come by in an enclosed system.
07-23-2005, 06:15 PM #10
At my last job all the machines had soluble oil in the hydraulics.
by machines i mean trucks as well.
same stuff you use as your lathes cutting/coolant.
anyone want to guess where I worked.
all the best..mark
07-23-2005, 09:42 PM #11
I would suggest changing oil and running the equipment a little more, wasting time with crock pots etc, isn't worth the time or money.
To drive off the moisture the oil will have to be heated to 130-160 deg range and it must circulate.
Operating the equipment also provides the benefit
of driving the moisture off the the engine oil too, your engine oil has more water in it than you think.
I spent a number of years working with oil chemists and proper operation clean oil and good filters were always found to yeild the best results.
07-23-2005, 11:12 PM #12
John, I must be as cheap as you say you are. I did what you are suggesting a few years ago. I bought a JD300 backhoe that had been sitting in this guy’s back yard. Oil looked like milk. First I got a new rubber boot for the gearshift handle. I knew I needed one because there was not one on it. We got the machine running, drove it some, and worked all the cylinders. Drained about 20 gallons out and replaced with new. With a backhoe, you cannot drain all the oil from the cylinders without removing hoses. So with the new oil in, it still looked milky. But was a lot better.
I heat my shop with a wood stove which is basically a large steel box made from ¼” plate. I had a SS pot that holds about a gallon. I placed a few firebricks on the stove and the pot on top of them. I found that if you put the pot directly on the steel stove, it would boil the oil, which I figured was bad for it. By adjusting the bricks, I could get the oil to just barely bubble. It would take a day or two for the oil to clear up. I would pour it thru a filter back into 5-gallon buckets.
Took a few months to finish but all it cost me was a little time. I was running the stove anyway. When it all was clean, I used it to change the oil in the tractor again. And did it again the next winter.
Can’t say for sure if it hurt the oil, but I don’t think so.
Go for it, Chief Mcgee
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