Cub Cadet 123 - Hydro Issue

[jgreer]

Hi all, not a new member, but this is my first post in a LONG time. 4 years ago I bought a 123 with a rebuilt engine and a hydro that wouldn't drive forward or backward. I intended on working on it back then and using it to push snow in the winter, but unfortunately my freshman year of engineering school was not the best time to pick up a new project . With all that is going on in the world today, I finally have more free time than I know what to do with so I am finally working on the 123 again.

I never got around to posting a picture of it after buying it, so I will insert that here:

After sitting 4 years, the battery is completely dead and I need to replace some cracked fuel lines in order to get the engine running. I checked over the transmission control linkage and trunion and don't see any issues there, so I went ahead and split the tractor so that I could work on the hydro for now. I was actually surprised how easy it was to split.
Here is how it sits currently:

Now, I'm assuming I can lift the rear wheels off the ground and spin the input shaft with a drill to test the hydro operation (please correct me if I'm wrong here).

I checked the fluid level, and it has the right amount of fluid. I'm not sure if the previous owner used Hytran or not, so I will be refilling it with Hytran just to be safe and replacing the filter as well.

This is my first experience with a hydro, so I would appreciate any direction or input from those with more experience than me. I have looked at the Sundstrand Troubleshooting guide, and plan on progressing through it to start.

Thanks in advance for any help, I will post updates on here as I work my way through it. Hopefully this 123 is back together and running smoothly soon!

 

[dschwandt]

Make sure you spin it in the correct direction which is CCW as you look at it from the front.
It will really tax a small drill motor as they take quite a bit of torque to spin.

 

[kmcconaughey]

Welcome back! Does that filter have a brand and/or part number on it? It's possible that it is not the correct type, might be an oil filter, not to mention it looks kind of beat up.

 

[gloughery]

Two things I learned when I did this with my first hydro are the manual vs auto valves and trunion wear. My 169 had manual valves and I put in autos, not sure which was OEM. The trunion is still a project but cubfaq has a good guide that has helped me tremendously. Good people here will be your best resource. And by the looks of your clean garage, there is a lot of room for more stuff. I bought a spare hydro to work on which allowed me to drive my 169 until everything was perfect...came a point where I had to decide to ride and play or just work, so I’m doing both. And I moved my other tractors out of the way so I could park my new 105 in the garage; hydros are slowly growing on me. I’m up to 7 tractors now and still searching CL and Marketplace for more.

 

[jbland]

sounds to me like the charge pump needs some attenuation

 

[jgreer]

Well I think I found the issue with the 123's Hydro.

I ended up pulling the hydro off of the diff housing and started disassembling it tonight. I didn't get very far before I found what I think is my problem

John B, I think you hit the nail on the head, the charge pump wasn't spinning with the input shaft

If I'm not mistaken, that little pin shouldn't be in 3 pieces.

I'm still going to continue disassembling the rest of the hydro unit just to make sure there are no other issues before I put it all back together, but hopefully this is it.

The input shaft is a little bit scuffed up where the charge pump sits, and I'm not sure if I need to replace it or if I can just polish it up with some emery cloth, or if it is even enough of an issue to worry about at all. Let me know what you guys would recommend.

While draining the fluid out of the diff housing, I found that someone previously had welded the differential in this 123. I can see how this may be beneficial if someone was using it as a puller, but then again I don't really see many hydro pullers, so I don't know why it was welded.

Kraig, unfortunately the filter doesn't have any readable markings left on it, so I'm not sure if its the correct filter or not. I'm definitely replacing it with the correct filter when I put everything back together

George, as far as looking for more cubs to fill my garage, I'm in the same boat as you always searching CL and Marketplace for another. Right now I've got my eyes set on another CC that has some extra attachments with it that's for sale in my area, just need to save up a little more $$ before I can make it mine. I also have the 122 that I inherited from my great grandfather that is currently in storage at my parents house, but I'm waiting to bring that out until I'm ready to start a full restoration on it.

 

[kide]

Make sure you index the pieces so you put it back together the same way as it comes apart.. the late (and missed) Don Tanner had a long thread a few years ago on rebuilding the charge pump in which he rotated the end of the pump 180 degrees.. Didn't work to well..

 

[mgonitzke]

I'd also grab a PDF copy of the service manual and familiarize yourself with the disassembly procedure of the hydro unit before you get too much further into it. There are some gotchas in there that will cause you to damage the unit if you don't know how it comes apart. Particularly, the spirol pins in the trunnion stub shafts where they connect to the swash plate. Upon reassembly, all parts need to be surgically clean.

I would strongly suggest replacing both needle bearings on the input shaft if you are going to take it all the way apart. When they fail, they will destroy the input shaft at a minimum and possibly the entire unit.