Milky Gear Oil

[Susquatch]

Gunna try something different.

Background

I have a 7ft bushhog (rotary cutter) that popped the bottom seal out of the gearbox a few years ago. Clearly hydraulic expansion. I suspected water in the oil because the remaining oil was milky. I replaced the seal (HUGE JOB) and tried unsuccessfully to change the gear oil. The problem is that the gearbox has no drain and has an upper and lower chamber separated by a bearing. No way to drain it all other than flipping the whole machine upside down. I can only drain out about half using a siphon.

I suspect (with high confidence) that the water is getting into the oil from condensation in the gearbox assisted by southern Ontario temperature cycles and high humidity. Gearbox cools in the evening and sucks in wet humid air. Temperature drops overnight, causing condensation inside the gearbox. Next day's heat bakes the gearbox and it breathes out dry air leaving water at the bottom of the oil. Next night draws in more wet air and the cycle repeats.

Temporary Solution

Overfill the gearbox with oil. This reduces the amount of wet air that can get in. But it is messy. The oil expands and leaks out the vent cap. That creates a space the following night and some water gets in.

Over time, the oil still got milky.

I unsuccessfully looked at ways to add a drain.

I tried insulating the gearbox. Didn't help.

Tried just changing the oil routinely. Got expensive real fast.

The Plan

Clean the oil and re-use it. Not so easy. The water doesn't separate easily.

So I'm gunna try boiling it off in a vacuum. The vacuum will significant reduce the boiling point so it can be a regular stove top process.

I've ordered a big cheap rice cooker and I have a vacuum pump.

Stay tuned.

Other suggestions welcome.

 

[Downwindtracker2]

Don't the oils have additives to capture water ?

 

[jorogi]

Had a JD 450 track loader years ago. It started making oil but I had some work that needed doing before I inframed her. I put a quick drain plug in the pan and at lunch and the end of the day I'd drain the oil. Put it on a propane ring whilst I ate and had nice clean oil when I returned to work. Did that for a month or so.

 

[PeterT]

Not sure what rice cookers go for & then the vacuum plumbing hardware/work on top - but 'degassing' pots are very common. I use this to de-gas resins. Nice thing is it has a clear plexiglass lid to see what's going on. And you have the valve right there in case you want to control vacuum ramp or bleed it off. ( Resins typically foam & it's possible to over-degas so you need this manual control). You might the the pot useful for other applications since you already have the pump. BTW you don't typically use the pot itself to hold liquid, just place your container of whatever inside it. No cleanup.

Removing water entrained in oil can be an interesting challenge depending on many variables. But some universal things that can help are (Stokes law): reduce the viscosity of oil, generally by heating. A shorter hydrostatic head for water to rise through. And demulsification chemicals. Here you are on your own because there may be effective additives but which may adversely effect the oil if they stay entrained.

There are other methods that are essentially distillation towers but you'll spend more on that than the oil.

 

[Susquatch]

Don't the oils have additives to capture water ?

Short answer is no. Some water can be absorbed chemically, but very very little. Sooner or later the amount of water that builds up cannot be chemically absorbed.

 

[Susquatch]

Put it on a propane ring whilst I ate and had nice clean oil when I returned to work.

The problem is the level of emulsification. I tried simple heat and it didn't work.

 

[Susquatch]

but 'degassing' pots are very common. I use this to de-gas resins.

Wish I saw your pots before I ordered the rice cooker. It's basically the same thing though. A clear lid and a seal to trap pressure. No gauge and no valve. I spent some of today today making the parts you warned me about...

 

[jorogi]

Would methyl hydrate help. The stuff for air lines and fuel ?

 

[Mike R]

Can you add a desiccant breather to the fill port? Catch the water before it gets in. Heres the idea, not necessarily the one I'd pick but found it fast.
https://www.princessauto.com/en/1-4-in-in-line-desiccant-air-dryer/product/PA0008105470

A little bit more off the wall idea - don't exchange any air with the outside. Plumb up a bladder that fills and empties as the gearbox heats and cools.

 

[OliverTO]

If your theory is correct and wet humid air is condensing in the gearbox and leaving water behind during the heat of the day, would you not see the same effect in an engine ( car, tractor or otherwise)?

 

[Susquatch]

A little bit more off the wall idea - don't exchange any air with the outside. Plumb up a bladder that fills and empties as the gearbox heats and cools.

I REALLY LIKE THIS!!

It would mean I wouldn't have to remove the water from the oil more than once. I think I could just install the bladder for storage and remove it for regular usage.

Surely they sell small bladders for outdoor Canadian weather.....

 

[Chicken lights]

Add a desiccant style filter to the vent system?

That's what I run on my shop loader hydraulics. Yes I realize hydraulics is not the same as a vent but desiccant is desiccant?

 

[Susquatch]

If your theory is correct and wet humid air is condensing in the gearbox and leaving water behind during the heat of the day, would you not see the same effect in an engine ( car, tractor or otherwise)?

Yes. In fact you do. But the oil temperature exceeds the boiling point of water and the water vapour gets blown out by gases leaking past the rings and sucked out by the pcv system.

It's one of the main reasons it's bad to not fully warm up your engine each time you use it.

Last but not least, water in the oil pan does little damage because it isn't trapped in a confined space when it freezes.

 

[Susquatch]

Add a desiccant style filter to the vent system?

Yes, but dessicants only reduce the humidity, they don't eliminate it. They also fill up and have to be recharged, and they don't work well in cold temperatures. That Fn thing sits outside all year long breathing in and out every single day.

I am running full speed ahead on the bladder idea. I still need to flush my oil but it puts a whole new spin on the brown bag hyper ventilating deal!

If I can find a small one I can just replace the vent cap with it.

 

[Brent H]

@Susquatch : on the ship the anchor windlass did this all the time. The solution - annual oil change and forget about it. Monitor for any abnormal wear. Results : bearing change for peace of mind after 40 years.

 

[Bandit]

Yeah, an engine can take in moisture from just sitting out side, the sun hitting it in the daytime and then cooling at nite can do it. I have a 2.8 ford v6 sitting here that appears to have done this. While don’t know the history of the car or engine there is a film of rust on most all of the Ferris metal surfaces inside, I have not seen this on a running engine before, drained nearly 2 litres of water out of it. If you want the engine, it’s yours, come and get it, sorry will not mail it!

 

[Susquatch]

@Susquatch : on the ship the anchor windlass did this all the time. The solution - annual oil change and forget about it. Monitor for any abnormal wear. Results : bearing change for peace of mind after 40 years.

Hi Brent!

No good in my application. The water freezing in the bottom of the gear case ballooned the seal and then pushed it out of its seat after 3 years. Before that I didn't know I had a problem. I sure knew it when I started up the Bush Hog with no oil in the gearbox!

It screamed like my wife when she gets pissed at me. Can't have my machines doing that to me too!

 

[PeterT]

Wish I saw your pots before I ordered the rice cooker. It's basically the same thing though. A clear lid and a seal to trap pressure.

I'm not really sure how they seal but are intended for holding internal pressure. Kind of the same but potentially different than vacuum, but probably not at these low-ish pressures. Google says about 1.25 atm pressure which is more than a vacuum pump from an absolute standpoint. Now vessels & seals don't really work the same way. You can crumple a can that would otherwise withstand higher absolute pressure.

Another option, really depends on your oil. If you can install a slender clear flex tube at the bottom of your oil chamber. If the oil/water density is sufficiently different, water should settle in the tube over extended period when the oil is quiet & warm after use. Ideally, open the drain & bleed the water until you see oil. Its probably not that easy. Some oils have an affinity to make tight emulsions. But you could just do a test in a sight glass.

 

[Susquatch]

You can crumple a can that would otherwise withstand higher absolute pressure.

The rice cooker has a domed lid. I'd expect it to be better at lower pressures than flat, but with your unit available, I'm prepared to fail. It was a cheap pot.

The best way to look at pressures is as a gauge pressure. Whatever vs 14.7psi.

Another option, really depends on your oil. If you can install a slender clear flex tube at the bottom of your oil chamber. If the oil/water density is sufficiently different, water should settle in the tube over extended period when the oil is quiet & warm after use. Ideally, open the drain & bleed the water until you see oil. Its probably not that easy. Some oils have an affinity to make tight emulsions. But you could just do a test in a sight glass.

No access to the bottom half of the gearbox. There is a bearing in the way.

 

[Martin w]

You gotta stop unhitching it in the ditch.

Is this a Bush Hog brand or John Deere rotary mower? There is no drain. You need to turn the mower on its side. If it's a John Deere, you have likely reached the end of warranty and it's time to purchase a new one

I usually throw a bucket over the gearbox for the winter, if I remember. Funny how the Bush Hog can never find room at the inn under cover.