I have a JD410 backhoe. There is water in the hydraulic fluid. It is white in color. Question, is there a drain plug where I can drain most of the fluid out. I haven't crawl under it yet to look. I will replace to 2 filters when I drain the fluid. I know I can't get all the milky hydraulic fluid out. I need to get most of it out and refill it with new fluid. Thank you in advance.
Look under the rear end... center line of bottom side.... should be a plug there... at least there is on my 310. On the filter side ( driver's right) there should be a "short" piece of rubber hose connecting the 'rear' to the filter housing.. Behind that would be a screen filter that is the 'pick-up' screen. Might be a good idea to pull that while you have it drained and check/clean/replace. The easiest way to do that is to loosen the filter mount and then it makes the job of removing (replacing) that short hose much more doable. Again... thats the way it was set-up on this 310b circa mid 80's You can check JDparts and look it up that way for your specific setup...but I think they pretty much did most of it the same??
With the price of fluid, consider either a process of disconnecting hoses and pushing fluid through each hose and cylinder in steps to waste as little fluid as possible and push as much of the old out as possible. Or draining the oil, drying it, putting it back in, running and repeating until the oil shows no more moisture. Oil can be dried by boiling, VERY carefully, vacuum dehydration, dessicant dehydration, absorbent filters, etc. None are easy. Draining and refilling will remove half the water or less.
IMHO, If you don't dehydrate the oil like Delmer suggested, or do a complete flush of the entire system with new oil you are wasting a lot of new oil and money by just draining the reservoir and refilling it with new oil. Just as importantly you need to determine how the water entered the system also.
I went through this every year on my NH machine. I don't know if it was condensation or rain getting in around the filler cap. I haven't had the problem since I built a barn to keep it in. Kind of an expensive cure for a few hundred dollar problem but I don't regret it.