Changing Hydro-Differential Fluid on 123
 

Ok I just searched and also watched a youtube video on changing the hydro fluid. lets see if I got this right:

Obtain 2 GALLONS (7qt) Hy-Tran equivilant fluid
https://www.tractorsupply.com/tsc/pr...ic-fluid-2-gal
Refer to Roland Bedell's filter cross-reference here for a filter option:
https://www.onlycubcadets.net/forum/showthread.php?t=12

1) remove spin on filter
2) remove rear cover bolts with big pan underneath
3)When it stops dripping, replace cover after cleaning surfaces as needed and with new gasket.
4) spin on the new filter
5) Find the oil fill and pour in 7 qt of the above hydro-gearbox oil (where is the fill point?).

Anything I missed?

Make sure you take the cover off first and drain it out. Hopefully there will be no water in it. Then remove the filter and then clean it out the tranny with brake cleaner as it will be gunky.
It is filled where you check the oil level on the rear cover.

cool. IF I find water, whats the process? flush with something else thats cheaper perhaps?

It is suggested that you leave the 2 lower bolts in the cover backed out only maybe 1/4" at most, that will slow the oil some, as you don't want it on yer
choose, socks, and mostly miss the catch pan.:biggrin2:
if warm, it comes out fast and before you can say oh chit, it is a a big mess.
Then the dog, cat etc. tracks it over a greater area,
or worse, someone is filming it sort of like a "Here hold my beer and watch this" moment.:beerchug:

George that really made me laugh! and I have said "oh chit" a LOT in my back yard over the years! :beer2:

Nothing special, Hopefully it will not be frozen.

I forget where I saw it but someone changed the fluid on a hydrostatic rear end once and then it wouldn't move properly; took him forever to figure out why. Turned out he wiped it out (the empty rear end) with a paper shop rag and a piece of it got left behind that he didn't see. It somehow made its way into somewhere in the pump or the relief valve, I forget where, and it stopped the flow of fluid, rendering said pump/rear end/transmission etc immobile. So if you go to clean it out avoid wiping it with anything that disintegrates easily.

One thing I mentioned before but do need to mention again is, I don't believe all 7 quarts of fluid will fit in the axle housing without flowing right back out the fill plug. Once you get it running, some of the fluid (about 1 quart IIRC) will be sucked up into the pump/motor, once fluid is in there the level in the case will have dropped, at which point you can add the last quart.

I, unlike you all, never had to deal with a catch pan, because when I took the cover off my replacement hydro, it was right about empty spare a slight bit left in the indent in the bottom of the case! :biggrin2:

No worries though, the suction tube (one of those long ones that snakes around the filter and pump shaft) had a pretty good crack in it and while sitting all the fluid leaked out. Replaced that suction tube with the one from the original hydro, no more big leaks :beerchug:

I watched your video, always feels good to breath life back into one of these machines don't it? That carb was definitely not saveable though, as clearly the choke was rusted shut.