Aaahhhhh! 1250 hydro not moving
 

drained and replaced fluid and filter. released relief valves, they move freely. when i start the engine and push hydro lever to reverse it gives out that classic hydro hum but won't move. when i push the lever to forward theres no hum and definitely no forward. when i pulled out the fill plug the fluid is frothy. when i took the diff plate off to drain fluid one of the bolts is stripped out and only snug to maybe 2-5 ft lbs. can that cause an air leak and give me the no go? just wondering if there is anything else i'm missing? getting frustrated

sounds like a priming issue.
Did you install the correct filter?

there was a PH 710 on it and i replaced it with the napa gold 1410

Curiously.... Is this a new problem that developed after the filter/ oil change OR you were trying to remedy the problem with oil /filter change?

If new,....The right oil? Enough oil? Filter on tight?

If old, no broken/missing pins on the driveshaft? There is front and back!

Foam in the oil is not the norm.
sounds possibly the filter is not tight.

After it sets for a few hours or over night, does it still malfunction?
We are assuming you cleaned out the rear when you had the cover off?
The differential/reservoir in not air tight, and a stripped bolt will most likely leak but cause no operational problems.
Sometimes after a filter change or prolonged no usage (like a year or more) they need a gentle shot with an air hose in the fill plug hole to prime the system.
Now I'm talking a rag wrapped around the air hose, just a few pounds at most, not full pressure from the compressor!
let us know the answers we asked.
Also are you sure the release valves are popped back up after you pushed them up/down?
The last thing I'd suggest if no joy with mentioned advice is to swap the release valves side for side and see if the no wine/hum goes to the other direction, that would suggest a stuck relief valve.

Both spiral pins are good. the fluid was completely drained and everything wiped out. replaced fluid with tractor supply Traveller premium trans/hydro fluid and the NAPA gold 1410 filter. relief valves are popped up and the ball bearing moves freely in both. i did flop them and similar result, it hums like it wants to go when putting lever in reverse, no hum when moved to forward. the tractor has been sitting for Lord knows how many years at the previous owners and now I'm trying to resurrect this thing. i will try the pressurizing

sounds air locked. did you try and put any fluid in the filter before it got screwed on? Yeah its tough, you certainly won't be able to get it "full" as it will tend to want to spill out to the bottom of the hole when spun on.... I have had other machines with the same hydro setup (Sunstrand 15) that have been a pain to bleed upon a fluid and filter swap.

yup i had the filter as full as possible b4 screwing on. still havent pressurized it yet (pulled the engine on my '79 bronco sunday😃, squirrel!)

i charged the trans with compressed air. still not moving. interestingly, the left valve nipple is now sticking. when i took the fill plug off there was a pretty good release of air, like a bunch of pressure built up in the case. any ideas where to go next?

if you are getting air pressure in the reservoir you have to be sucking it in somewhere.
the suction line is under the oil level so it shouldn't happen.
is the nut tight on the suction tube on the bottom of the hydro ( it is by the side of the filter and goes into the front of the rear housing at the bottom):bigthink:.

i'll look into that in the morning and reply asap

took the suction tube off put a new o-ring on. havent fired it up yet. but i'll re pressurize it and start her up some time this week

Please elaborate, I don't remember an "O" ring on the suction tube.
The top has a tubing nut on the flair where it screws to the hydro,the other end where it goes into the diffy case/reservoir, has a brass compression fitting.
if they don't leak they are usually ok.
Reviewing:
Did this tractor work properly before you decided to change fluid/ filter?

where the suction tube screws onto the hydro pump there was an old dry rotted o-ring, no other compression fitting or tubing nut. so i replaced that. the 1250 is a project i picked up in march. it was rough, sat for lord knows how many years. previous owner had it given to him by an old collector who passed away. it looked like someone scavenged parts off it. it was missing ignition, pto switch, coil, starter. i've gotten the engine back up running. i'm just stuck right now on this tranny.

ok if you look at the Cub cadet parts look up at the top of our page banner
you will see a fitting that screws into the hydro, yes it has an "o" ring but I have never ever removed that fitting as no need to, but no problem.
I just loosen the tubing nut on the tube that screws onto it,and remove the
suction tube.
Thank you for the clarification, we now know no one has any idea of the hydro's condition, and we should assume nothing.
As far as we know a rag/obstruction could be in the suction tube.
Or someone could have swapped charge pumps and left the "O" ring seals off or installed it 180 off rotation and it won't pump.
Or worse it was "done blowed up" as the good ol'boys say in NASCAR
So where does that leave you?
swap in a known good hydro from a reputable seller or keep trying to find the hidden cheese like a hungry mouse.
That is what I would do because I am "curious George"
Sorry I can't help more, maybe others will have a idea.
does the charge pump look as it has been removed/loose bolts?:bigthink:

thanks george! i'll re check the suction tube for obstructions. the gears all move freely, i checked that when i changed the fluid. if i take the hydraulic pump off is there anything to look for?

The charge pump MUST be installed the way it was originally installed and not turned CCW from the original position.

Question: Did this unit work properly BEFORE you changed filter and fluid?

nothing worked when i took ownership this march. probably hasnt run in last 15 yrs.