782 Hydro Leak

[glippert]

I finally decided to believe that Spring is here, and I removed the snow thrower (QA42A), chains, wheel weights, and rear weights from my IH 782 (s/n 682355). And, since it will be a little while before I need to install the tiller, I decided to finally change the cork gasket to cure my hydro leak. I removed the fender pan and pressure washed several years worth of Hytran & garden soil from the entire rear half of the tractor. Then I decided I should follow Richard Christensen's (I think?) FAQ to ID all leak sources. Sadly, within a couple minutes I saw Hytran dripping from the left, trunion shaft seal. I've read many times that this is the one seal that can't be replaced without opening the pump, so I went to the manuals (1974 Sundstrand and 1990 Sauer Danfoss). That's when I got confused: both manuals have the same paragraph, saying all the seals can be replaces without opening the pump. Am I reading this wrong? I trust the experience on this forum more than my own comprehension of a manual. What say you all? Do I really have to open the pump and replace the seal from the inside? And, are there any good pictorials on the forum for this process? I seem to recall Marlin H sharing a wealth of information on these hydros, but I haven't had any luck with my archive searches. AND, the third paragraph in the manual also says to wrap the shaft with thin plastic, and lube it before sliding a new seal on the shaft? Does the plastic stay on the shaft? How can such a short section of manual confuse me so thoroughly?

 

[mgonitzke]

For the configuration used in the Cub Cadets, the LH seal cannot be replaced without disassembly. I would use the IH service manual instead of the Sundstrand or Sauer-Danfoss manuals, as it has the instructions specific to the variation of the hydro unit that you are working on.

 

[glippert]

Thanks, Matt. Good to know my memory isn't completely gone (yet)!

 

[glippert]

I have my hydro pump/motor opened up and ready to remove the swash plate. Per the manual, I need to mark my punch precisely at 15/32" (11.9mm) to drive the pins just far enough to remove the shafts and swash plate. I'm using a pin punch, with the little nub at the end. Should I measure from the very tip of the nub or from the actual flat part at the base of the nub?

 

[dschwandt]

I would not use a pin punch for that operation.
Use a brass drift to avoid damage to the shaft.

 

[glippert]

Thanks Dave.

 

[wh cc guy]

When you put things back together be careful with the swash plate and put it back in turned the same way it was when disassembled.

 

[glippert]

Thanks - I will. I'm pretty paranoid about doing this open heart surgery, so I've been studying the manual a lot, as well as FAQs & old posts, and even youtube. I'm aware that the swash plate, the valve plates (pump vs motor), and the charge pump housing can all be installed backwards/incorrectly. I even made the wooden block to hold the assembly steady on the bench. But I'm open to all suggestions and advice. I really appreciate and respect the combined knowledge and expertise on this forum.

 

[glippert]

Well, I got the shafts & swash plate out. Without a doubt, the scariest thing I've done to a Cub Cadet. When I got the pins down almost to 15/32" and everything was still tight, I double, triple, and quadruple checked my tape marker, then GENTLY tapped, tugged, tapped, twisted, etc, until (after what seemed like hours) the shafts were both free. While tapping, I was trying to decide whether to cannibalize the 147, 1450, or 1650 when I ruined it. But despite my negative self talk, suddenly all was good! And Spee-Dee Delivery showed up today with my parts (THANKS CHARLIE!), so I can have my nephew weld the trunion control repair part, replace seals and start reassembly before I lose anything or forget wghere it goes. Here's a pic of my happiness:

(The blue tape is hold the the repair part to it, so I don't lose it.)

 

[glippert]

When you get the new cork gasket mounted, you know you're headed in the right direction.

 

[glippert]

SUCCESS! I got everything back together today, ran it through its paces in the garage on jack stands, took it for two, count 'em - two, test drives around the block, ran forward and back at various speeds, and no signs of any leaks! And it even goes faster forward than back - guess I got the swash plate correctly oriented, huh? I also rebuilt the steering, did the trunion control repair & replaced the damper springs, shimmed the hydro cam plate, etc, and adjusted the speed control lever tension. It's never behaved so well while I've owned it. Thanks to this forum and members for providing the information and courage I needed to attempt this scary journey (opening a transmission). I can hardly wait to go to my brother's shed and look under my 1450 & 1650 to see if they have marked their spots, lol.

Did I mention how happy I am about this? It's going to be a game changer for tilling, to maintain a set ground speed, have good tight steering instead of 180 degrees of slop, and not having to add Hytran with the tiller attached.

It doesn't take much to make an old man happy, right?

 

[kmcconaughey]

Greg, glad to hear that the 782 hydro repairs went well!

 

[jkoenig]

Good for you Greg! Glad to hear it worked out. I haven't figured out yet if mine doesn't leak, or if it's empty from the splits in the filter that probably came when the driveshaft came loose.

 

[glippert]

Thanks. Looking back, it wasn't as bad as I feared. Just had to follow the manual, step by step. I'll keep my fingers crossed for you, but if it does leak, don't put it off for years like I did. Good luck!