Water in hydraulic system

[Blue-Fox]

Bought a used 720A this winter with a Wing on it when my Cat trans went out. I’ve had some weird hydraulic probs that don’t make sense, operator said it feels “stiff” from setting a few years. Machine is loosening up and working pretty good now. Having a random articulation going hard right and staying that way. Blew a hole in the steering line the other day and when I picked up the new hose the hydraulic shop said there was water in the old one.

I’ve had a piece of swamped equipment before and took a full drain and purge and tank cleaning to get it dried up.

You guys know any cool tricks for getting water out of a hydraulic system?

 

[Blue-Fox]

Will one of those water stop fuel filter elements grab the water out of the system?

 

[Entropy1]

Water is heavier than oil and will find the low spots within the system. If fluid velocity isn't high enough, localized low-points within piping/hoses (and any other system-components with localized low points) will trap & retain water - which can cause serious issues in freezing temps.

Most spin-on hydraulic return-filters will trap water - even if they're specifically not designed to separate water. The return filter needs to be orientated vertical and large in size to effectively separate water. If the filter is too small (aka fluid velocity through the filter is too fast) it will flush the water through the filter & back into the system - in lieu of trapping it.

The best place to start is the bottom drain on the hydraulic tank. Pull the plug and drain out the water - until oil comes out. Run the machine, let it sit, and repeat. Ensure the pump is not drawing in standing water from the hydraulic tank - before you try to dewater other parts of the system.

 

[Delmer]

Water absorbing filters will take the water out, but they are expensive for the amount of water they take out.

I've dreamed of building a vacuum dehydrator out of an old electric water heater, a refrigerator compressor and some valves and hoses, but then you'd HAVE TO HAVE a centrifuge too, so that's not going to happen.

Heating the oil and bubbling air through it is remarkably effective for how simple it is. If you do it in the tank, insulate the top of the tank so the water doesn't condense and drip back down. If you drain the tank into a separate container, set it up so you can pump the fluid easily with a few PSI of regulated air pressure because you'll have to repeat the process several times. Every time you do it, and then run the machine, you'll mix more water out of the system with the oil. Once you get the oil dry, then change the oil and filter, or at least the filter. I threaded a piece of steel brake line through a rubber hose for a simple heat exchanger, the air going through the brake line to the bottom of the tank to bubble, and the hot moist air going the other direction to preheat the air, sloping down so the condensation drains out.

 

[John C.]

The saying that water and oil doesn't mix, doesn't apply to hydraulic oil. Hydraulic oil is formulated to combine with water and form a colloid. It can be heated to a certain point and the water will form into a vapor and leave the oil. It's called dehydrating. The other method is to install water filters on the system but last I checked, the filters are very expensive and plug up real fast. It cost about the same or more to try to filter a badly contaminated system than to drop all the oil and flush the system. Do a search for "water in the hydraulic system, heavy equipment forums" and there will be several discussions over the years.

 

[Entropy1]

Drawing vacuum on the system will boil off standing water (see low pressure saturated-steam tables). The problem with doing this, is that the machine's valve body will typically isolate the load-circuits from seeing the vacuum - thus you'll have to draw down each isolated part of the system separately. Use caution on the main tank. If you draw appreciable vacuum on the main return tank, you might actually crush it like a can (most return tanks normally see a small positive differential pressure, and never get subjected to a strong vacuum).

IMHO, drawing vacuum on the system to remove water is overkill in most situations. Vacuum drying is something you'd normally accomplish on a large closed-center hydraulic system.

 

[John C.]

The dehydrators currently being advertised are run like a kidney system. The dehydrator is plumbed into the reservoir and oil is drawn in and subjected to vacuum and heat, then pumped back into the machine. All the functions have to be cycled enough to remove the water in the system. I contacted the manufacturer for a price and was told around $30K. It is both a slow process and it includes some expensive filters as well.

I would suggest getting an oil analysis and find out how much water you actually have in your system before you go any further.

 

[1693TA]

I winched a TD-15 out of a pond and the hydraulics were full of water. I think more water than oil actually as the tractor was almost to the top of the ROPS, (submerged). I helped the owner drain all the fluids and fuel, remove filters, then disconnect all the hoses and fittings possible that would be a low spot. Compressed air was used on hydraulic cylinders and lines by pressurizing them, and then dumping the air suddenly. Was a mess for sure. All removed hoses were washed in warm solvent bath, reinstalled and the system refilled with reclaimed clean AW-32 oil in the hydraulics for a flush. The tractor received proper fluids in it's respective reservoirs. Upon engine start it was allowed to warm and then drain cocks "cracked open" daily for several days till no more water was found draining. The hydraulic oil was then changed along with filters again.

To my knowledge, no damage to any system as that tractor was around for several years afterward.

 

[Entropy1]

If you don't have standing water in the system, but only have water-saturated oil, then simply drain & change out the oil. It gets expensive if you change the oil, and there's still standing water in the system - you'll be changing the oil over and over to clear the standing water.

Oil/air coolers are your friend. When they go bad, they simply leak. Oil/water coolers however are a complete nightmare. When the tubesheet fails, or a tube ruptures, you're cross-connecting water directly into the hydraulic system. And if your hydraulic system is on a ship or submarine, you're pumping "seawater" directly into your hydraulic system.

Most earth moving equipment hydraulic systems are open-center with a slightly pressurized return tank (water normally cannot enter). If water is getting into the system, the source of water contamination should be identified/corrected first.

 

[Blue-Fox]

I don't think its Saturated, the machine lives outside in the cold and fires up and operates at -20F without issues other than it seems "stiff" Lol. Which is now making sense with little ice plugs all over! It's been out winging roads and worked about 80 hours since Xmas when I bought it. It sat for two years before that, prior owner said he worked it about 80 hrs that prior winter.

One of the rams on the wing leaks almost constantly an oil film on the body and has a bunch of bad spots in the ram that lead me to believe its Ice getting past the scrapers and seals when that cylinder is retracted. I will be draining the tank to see what is in there for sure.
Now that I think about it, there is a random deal that we were trying to track down the cause of how sometimes when we would fire up the machine cold the articulation would crank hard to the right and doesn't want to return. Like the switch doesn't even work. We ended up putting the pins in it so it can't articulate waiting on a solenoid block, since the retainer nuts for the solenoids on the block are rusted away so bad they are going to get drilled out to swap out solenoids.

I have an old forklift that got rented to a commercial fisherman, that they swamped on the beach, flooded with ocean water and silt. They swamped a tractor trying to drag it out of the surf. Its not the first time I dealt with water in a system but I was hoping there was an easy way to trap it in a filter or drip leg. Last time with the forklift I poured a gallon of straight methanol in the hydraulic tank and let it circulate. That seemed to help grab the water and bring it all out the drain with the fluid. But had to cycle about 3 times the normal hydraulic system volume to get all the cloudy fluid out. What a nightmare!

Guess its time to get the rain gear on and pull plugs.

 

[Blue-Fox]

Really appreciate the feedback!!