Kubota L3400DT-air in hydrualic fluid

[asic ace]

I seem to have the common problem of a cracked suction hose and my fluid is a milky white. Fortunately, the hours is at 389 so I'll do a 400 hour service after I replace the hose. I'll be replacing all fluid and filters. I have a few questions:
1) Is the fluid left in the hoses an issue or is it mice nuts? I plan to raise all cylinders against gravity before draining and drop them all and drain some more.
That should (I think) empty all of the cylinders but not the hoses. Should I be doing something different?

2) There are two filters, an HST filter and an expensive hydraulic filter. What are those for? Why two?

3) I forget the last question so I'll just ask for any advice offered.

4) I remembered the third question. The steering has degraded to the point of being manual steering. Is there anything I should do to flush the steering lines?

-- Don

 

[Fallon]

HSTs are much more precision & sensitive than the rest of tractor hydraulics. So they protect them with finer filters.

There will always be a decent bit of fluid left in the hydraulic system. Don't wory about it or try really hard to get it out. Just dump the sump & refill it. Manufacturers expect this, similar issue with swapping impliments between machines.

There are techniques to prevent fluid loss when changing hoses or filters (shop vac on the fill port), but moot if you are doing a fluid change.

 

[100 td]

Milky fluid is generally water in oil, aerated fluid is clean fluid with microscopic air bubbles in it. Crack your drain plugs at each axle and let a small amount of fluid drip into a clear glass and allow the fluid to sit, and inspect the oil. Do the same for tranny drain plug. If you have water, check all your breathers, they tend to shrink and not seal, so when washing water may enter. I lift my hoe and FEL and drain, then let them down to get as much old fluid out of the system as possible, and push my stabilizers down by hand, especially if there is any contamination. If your oil is squeaky clean, less need to do this.