Strange Hydraulic Fluid Cloudiness (Massey GC1725M)

[Robin Veerman]

Yes for me too, 2/3 hours northwest of you in Ontario, the winter was off to a slow start. Been busy the past couple of weeks though. Good on you to be watchful of your fluids. That’s one of the easiest maintenance items to do, observe/check levels, and the most important first step to equipment longevity. Keep us posted…

 

[hube2]

Could it be that the cold oil entrains some air because of the higher viscosity and then releases the air once warm and thin?
Eric

Cloudy oil could be due to water in the oil. But it can also be due to tiny air bubbles. After going through all the valves with the 3pt last, the oil dumps into the transmission. It can entrain air then. The bubbles would be gone by the time the oil reaches the pickup point at the bottom of the trans.

Keep in mind that the sight glass is at the back which is where the oil dumps in. So it's close to the source of the bubbles. The pickup is about 6 feet forwards, at least on my Branson. The glass being close to where the oil dumps in would also explain the higher level when the tractor is running.

Right now, as rScotty says, seems the most likely.

Also reading this that I found

Release of dissolved air — All hydraulic fluids contain an amount of dissolved air, which can be released when the pressure is decreased rapidly. This can occur at valves and orifices, as well as where the fluid returns to the reservoir.

I also read somewhere else that the higher viscosity of the cold oil creates more pressure, not sure about this one though.

Then there is the fact that the fluid dumping back into the sump will be warmer than the fluid at the top it is dumping into and the sight glass is at the top of the fluid. Could possibly be a contributing factor. Would warmer oil hitting colder oil cause the release of air as well?

But it all kinda makes sense.

I won't say "mystery solved" just yet though.

 

[jonsstihl]

I think eptm hit the nail on the head. the cold oil has a harder time releasing the air bubbles stirred up by the normal operation of the system but once it warms up the air bubbles can move to the surface of the oil more freely.

Makes sense. I don't have a sight glass on my tractor.

 

[hube2]

So I went out yesterday, 40F outside. I let the tractor warm up for 10 minutes. Fluid had the cloudy appearance in the site glass. I have nothing attached to the mid PTO and I ran it for about a minute. Checked and the cloudiness was gone. Couldn't get pictures.

Anyway. I have no leaks, I've never seen any oil on the ground. Fluid is maintaining level. I'm going to call this normal, at least for now.

 

[RjCorazza]

My previous Kubota L3410 had a sight glass, and the oil would always look cloudy after use (through the glass). There was zero chance for water contamination, so I eventually just ignored it.
When draining that same tractor warm, the oil coming out was always crystal clear.
I prefer the dipstick on my current L4060.

 

[hube2]

Yeah, like I said in a previous comment, I had never looked at the glass between warmup and shut down before. The only exception was after I mounted or unmounted the FEL because you loose a bit of fluid each time you do that. I'll just continue to check the level, as long as I'm not gaining or loosing I'll assume it's good. I was planning on changing the fluid in the spring and I'll see what it looks like then.

 

[rScotty]

Yep, air. Thanks for checking.

 

[GeneV]

If it's working fine I wouldn't worry about it.

 

[Robin Veerman]

Well, just remember that air bubbles in the oil might result in reduced lubrication compared to oil without air bubbles…

 

[hube2]

Well, just remember that air bubbles in the oil might result in reduced lubrication compared to oil without air bubbles…

There isn't any way to know if the bubbles are just at the top or not. My assumption here is that they are just at the top because running the pto for 1 minute clears them. If there were bubble throughout the fluid they would not clear that quickly.