What Should Drained Hydraulic Oil Look Like?

[F_22]

Did the 50 hour service yesterday on my TC33D. When I removed the hydraulic filter I lost several quarts, no surprise there.

But the hydraulic oil that drained out was not honey-clear as I expected. Instead it had somewhat of a milky and frothy appearance. The tractor had just been run and the FEL exercised to warm things up before I worked on it. Is this air, or worse, water whipped into the oil? Should I drain and replace the entire 8.8 gallons?

I got a good deal on this 2002 TC33D because it had been repossessed by the dealer with only 8.5 hours on it but is still under warranty. But it sat on their lot for over a year without being run. Could water somehow have entered the system while it sat outside? Shouldn't the dealer have noticed the milky hydraulic oil when they installed the FEL just before I took delivery?

Thanks in advance,
Bruce

 

[jinman]

Bruce, I'd check the dipstick in the reservoir and see how the oil looks there before I operated the tractor and then again after it warms up. If the oil stays pretty stable, I would not be too concerned. If it's milky in the reservoir, you may need to drain and replace the oil.

My oil was clear to honey-clear in my tractor even until I changed it at 300 hours. I only checked it in the reservoir though.

 

[Bird]

Put some of it in a glass jar and leave it sitting overnight and see whether all the air bubbles disappear and/or whether there's water in the bottom of the jar. It does sound like a little water might be in there.

 

[JerryG]

Bird's point about putting it in a jar is a good one. I have seen fluid with air that took up to three days to go clear again. So give it a couple days or three. If it comes out milky on the dip stick, look at it close. It it is water, it will look real slimmy. Water and aeration will both cause the fluid to look white.

 

[AndyMA]

I like Bird's idea also. I think the system probably picked up a little mositure sittin gfor all that time. It's amazing what condensation and a little leakage can do.

Andy

 

[Soundguy]

If he has access to a centrifuge, he can speed up the clarification process, to help determine if it is air or water ...

If it were me.. I'd want to know why either one was happening.

The return line should be in an area situated so as not to incorporate air into the system, and NH spec oil shoul have anti-foam addatives.

If it is water.. I'd look for shifter area, and breather caps.

Course if it was re-poed.. that means the owner may not have been big on maint either.. considering he wasn't paying for the tractor.. etc..

Soundguy

 

[F_22]

OK, I took Bird's advice and let a 3-4 oz. sample from the reservoir sit in a glass for about 48 hours. No water has separated out but it still looks cloudy, although not as cloudy as when I first put it in the glass.

Wonder if it's air, and how it's getting in there? All hydraulic functions work fine. FEL and HST both whine, even howl, until it warms up on a 35-40F day, then quiets down nicely. But I've read other posts saying the same thing.

Thanks for the advice, all.
Bruce

 

[Junkman]

Many times the moisture in hydraulic fluid will become homogenized with the oil. To know for sure, place it in the freezer and if it gets hard or a gel like condition, then I would replace all of it. In fact, you might have to do two oil changes to get all the moisture out. When a tractor sits outside in the rain, the moisture is drawn into the tank when it is warm in the day time and cool in the evening. I have even seen water get past the seals on the pistons and get moisture in the oil that way. Tell the dealer, because if there is moisture in the oil, it can effect the hydro pump in a negative way. Save an oil sample for them. Better to err on the side of caution than to find out later that you should have notified the dealer because of a failure outside of the warranty.

 

[jinman]

I agree with Junkman that you should let your dealer see a sample of this oil. Since your tractor was a repo, there's no telling what the previous "owner" may have done out of spite when he knew he was loosing his tractor. You always hope for the best, but you really have no idea what might have been poured into your reservoir. With what you've seen, I think an oil change (or two) is cheap insurance. Good luck.

 

[JLD]

After I did my 50-hour hydraulic service, I drove around and warmed things up and found I overfilled it a little. I drained about a quart from the drain plug, and the fluid had the same milky appearance. As it sat there a while the milky look seemed to go away a little. I am guessing that the fluid mixes a little with the air in the system. I'm not worried about mine, but it has not been out in the weather for a year. I'd put some in a jar and see what happens.