Oil & Fuel JD 4100 has milky hydraulic fluid...why?

   / JD 4100 has milky hydraulic fluid...why? #1  
I

imq707s

New member
Joined
Jun 29, 2017
Messages
2
Location
Strafford
Tractor
John Deere 4100
I noticed the other day that my power steering felt a little notchy and not smooth and the brakes were making some noise.....and then today I noticed that the 3-point hydraulics up and down felt really rough, almost like there was air in the system.

I checked the dipstick for the hydraulics fluid in front of the seat, and the hydraulic fluid is really white and milky looking....it's got moisture in it. It's been a few years since I've changed the hydraulic fluid, but the tractor doesn't really get used much...maybe 40hrs a year. Usually for short durations....fire up the tractor, move a pallet around, or move a trailer and then 20ming later shut it off.

I'm just trying to figure out how the moisture got in the hydraulic system.....is it just from humidity? Is it from using it for short durations and not letting the hydraulic fluid get hot enough and evaporate off the moisture?

I've got some JD Low-Viscosity Hy-Gard to dump, clean the screen filter, and refill the hydraulics this weekend. I'm assuming it wouldn't be a good idea to do it again after a few hours of use...just to get all the moisture out. Hopefully it didn't damange the pump, brakes, or anything in the hydraulic system.

Did I just wait too long between fluid changes? Any other ideas on how moisture got in the hydraulic fluid?
 
   / JD 4100 has milky hydraulic fluid...why? #2  
Welcome to TBN.
Sounds like you are on the right track, about how the moisture got into the tranny fluid. Gear or hydrostat?

Did this tractor also sit outside in the weather? If so, I would suspect rain water found a way to enter the system.

Given that the fluid is contaminated, I would for sure dump it and refill with new. Then monitor the new fluid closely to evaluate the oil. Likely will still have some residual contamination but hopefully can then assess whether to change fluid again.
Wish you good luck.
 
   / JD 4100 has milky hydraulic fluid...why? #4  
I had a 4200 with milky trans fluid. I ran it for quite some time until it literally froze in cold temperatures. Changed the fluid and flushed the lines and cylinders to steering and on loader. Quite a process but worth it. It prevents you from dumping the oil a second time.
Even with flushing, you're not getting everything out. Just change it sooner next time.

How the moisture got in, I have no idea. It was a collar shift. No boot on top of the tranny. Yes, it sat outside. I bought it used with unknown history. Back then, I didn't know this forum would exist.

No damage to the pump.
 
   / JD 4100 has milky hydraulic fluid...why? #5  
Yes, early tractors had a metal 'collar' on the shift lever. Wasn't until later rubber boots were used.
 
   / JD 4100 has milky hydraulic fluid...why? #6  
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