Changing hydraulic fluid ?

[Birdseye]

Hi,

In repacking the boom and stabilizer cylinders on a 580se that had very deteriorated seals , when draining the hydraulic fluid out of the tubes, I noticed what appeared to be some water in the bottom and the hydraulic fluid is milky white. Once done with my repacking, I thought maybe I should change out the hydraulic fluid and start over with fresh fluid. I've not done this before so I assume there is a drain at the bottom of the main tank and I'll have to drain each cylinder tube by cracking open the upper & lower fittings and letting them drain out slowly given that there maybe fluid trapped above the pistons.

Is this a waste of time to drain the cylinders, should I just drain the main tank and refill ?

Thanks.

 

[aighead]

Here are a handful of links that should set you on the right path...

https://www.heavyequipmentforums.com/threads/hydraulic-flush.82627/

https://www.heavyequipmentforums.com/threads/getting-all-hydraulic-fluid-out.19687/

https://www.heavyequipmentforums.com/threads/pc60-2-hydraulic-oil-change.46200/

 

[Tinkerer]

It is a waste of time and oil to just drain and refill the hydraulic tank.
Or just the cylinders.
It is a time consuming process to do the flush correctly.
Have at least 25 or 30 gallons of new oil before you start.
I used 40 gallons when I did my last one.

 

[Birdseye]

aighead, thanks for the links.

The post by Willie59 on flushing the system seems to be the simplest and fastest way to do the flush so that’s what I plan on doing.

The comment by Maytag:
“...in a steel mill environment we run a water/glycol mixture instead hydraulic oil because it is a fire retardant(40% water)....” begs the question what IS the negative side of water in the hydraulic fluid?

 

[Tinkerer]

Corrosion and lack of proper lubrication.
It would be hell on a hydraulic pump.
Enough water and it would freeze if you are in that kind of climate.

 

[Nige]

As Tinkerer mentioned, water is neither a good lubricant nor does it prevent corrosion of system components.

The comment by Maytag: “...in a steel mill environment we run a water/glycol mixture instead hydraulic oil because it is a fire retardant(40% water)....”

There are a lot newer versions of fire-resistant hydraulic fluid for steel mill (and similar) operations than water/glycol. The most common are either an invert emulsion where the water is emulsified. That way the water never comes into contact with the surfaces that need lubricating. The other option is a synthetic hydrocarbon (ester) fluid. Either is 100 times preferable to a water/glycol mix from a lubrication/resistance to corrosion aspect.

 

[Tinkerer]

Dam, Nige!
I learn something new from you every week.
I didn't know that stuff existed.

 

[Birken Vogt]

I've got an ancient backhoe that has had the most watery hydraulic oil the whole time the last few owners have had it.

It freezes nightly here, but not very hard.

Everything is junk on it and not worth fixing, but it has been that way for years and years and it still works (occasionally).

Of course it is a bad idea, but I am just putting it out there, it can go on for some time.

 

[Birken Vogt]

Not sure if it was in the above links but here is another idea.

 

[Birdseye]

Impressive video , I like how you show that the external filter machine removes the white contamination (water?) and others particles, but I must have missed where the water and other contamination is removed from the filter machine , I’m curious how much water you removed from your 30 gallon system.

where do you rent those things and how much do they charge?

 

[Delmer]

The filters are special water absorbing, and they don't have a large capacity for water. Vacuum dehydration or boiling are other ways to get the water out of the oil. Repeat until the whole compartment is dry, THEN change the oil if needed. or take the hoses off one by one and flush everything...

 

[Birdseye]

For the sake of discussion I’ll mention the two alternative approaches to removing water from hydraulic fluid which come up in a web search:

1) YouTube video - fella fills a metal container with milky white fluid then boils the fluid with a hot-water heater element. After a while the fluid is clear and a bit darker.

2) Retrofit a 2nd port on the top of the hydraulic tank, then run a continuous flow of dry air from a room dehumidifier thru the head space above the fluid in the tank. Apparently this will over time draw the moisture out of the fluid.

The first approach sounds plausible, the second seems like it would take a long time.

Any thoughts?

 

[Tinkerer]

Keep in mind there is a lot of oil in any system, not just in the reservoir. I don't know if someone older than 50 would live long enough to use the alternatives to completely remove all the water.

 

[Delmer]

Yes, headspace dessicants/dehydration would take a LONNNNNNG time to remove liquid water from the bottom of the hydraulic tank, or stabillizer cylinder. Not so bad if the machine is running 24/7, but not going to work for most homeowner's antiques.

If you boil oil, it will bubble up and make a huge fire easily if there's any ignition source, be prepared. And it will have to be repeated several times to get the whole system acceptably dry. I'll have to find that youtube video, I've thought a water heater with suction applied would work swell, allow for easy suction out of the reservoir, spray the oil through and orifice under vacuum and heat.

edit: found the videos, gitter done! looks good

 

[Birdseye]

The scorecard so far then is:

- replace all oil after complete flush: 10 points, simple diy solution

- rent a filtration device: 9 points , hard to find device, expensive to rent but gets it done.

- boil the oil as per utube vid, inexpensive and potentially hazardous, heat may affect oil negatively, but seems to be effective
7 points


- headspace dry air water extraction, 2 points, way too slow, requires parking machine in building

 

[stinky64]

Is it actually possible to make any system absolutely pristine after water has been introduced without one of those fancy pumps in the youtube video? I've tried several times as per service manual procedure to accomplish this daunting task, working cylinders into buckets moving the hoe back and forth, when draining plugs on the bottom of loader frame (580c) always get a few drips of water....always have that slight discoloration..and at $40 plus per bucket, when do you throw in the towel? It gets below zero here in winter months and it has never frozen up on me..only thing that concerns me is premature pump wear....

 

[Delmer]

The 580C hydraulics was far from pristine the day it left the factory, most buckets of new oil contain plenty of dirt also, do your best and don't worry about it.

It should be possible to remove all of the visible/milky water with enough repeats of the boiling or bubbling. The trick is to set it up so that you can repeat the process easily enough to keep going until it's reached acceptably clear oil.

 

[stinky64]

Copy on the dirt in the buckets...I've got an old maple syrup sock that I strain all new fluid into clean buckets before use in any of my machines...I think the oil producers must have stock in the filter market as well...

 

[Tinkerer]

Paint strainers work good enough for me. Very slow process.
FWIW, My machine had hydraulic fluid that looked like a vanilla milkshake when I bought it.
I posted the way I flushed it quite some time ago.
It now looks as good as any new oil in a bucket. Probably cleaner because I changed the filter before and after I flushed the system.

 

[NH575E]

The last time my machine looked to have water in the hydraulic fluid it seemed to emulsify in the oil. In the past I could suck the oil out and over time it would separate so I could pump the clear oil off the top. Last time I let some sit for months and it never separated. I suppose the oil could have improved additives that caused it but I have always used the Premium Travelers from Tractor Supply.

I have never done a complete change. I just change the tank and filter and settle for the oil looking mostly clear. Since I got a barn to park it in it has remained clear. We haven't had the shift form hot to cold and cold to hot since the last change so time will tell.