The Unexpected Twist and Turn.
The snap ring was smaller than a dime, and probably cost about a nickel to replace, but it became clear that the problem with the machine was probably due to the failure of the snap ring, and not the scarred piston. Now I had to figure out where it came from without dismantling the entire tractor.
Time to hit the service manual again, and look through the pictures to find out what and where the snap ring came from. I poured through the manual looking for anything with a snap ring reference, but to no avail. I couldn't find it anywhere, and I was becoming concerned. It had to be something small, but usually snap rings hold bearings in place and bearings are usually on shafts. Now shafts are round and usually can't be removed easily. So if it was a bearing failure as the result of a snap ring failure, that would probably require "breaking" the tractor into three pieces. The front with the engine, the middle containing the transmission, and the back where the rear wheels and such are. This is the worst case scenario, and the one we were hoping to avoid.
I grabbed the trouble light and decided to get under the tractor and look up into the transmission from the bottom in the hope that I could see what was wrong. If you can diagnose a problem, then you stand a much better chance of learning how to fix it.
As I was looking inside, I had no idea what to look for, but I knew it was something small and round and had a groove for a snap ring. I was just about to give up when I noticed a metal hydraulic line that was rubbing on the main pump shaft. As dumb as the engineers who designed this tractor were, I knew they wouldn't have metal rubbing on metal. I cocked my head to the side, adjusted my light, and there it was... the other end of the hydralic line had a fitting that was pushed out of it's designated orifice.
I didn't know if it was where the snap ring came from because they usually don't connect hydraulics with anything but threaded fittings, but it was definately out of place, and so that was where I needed to start.
I had to take out the main hydraulic pump to access the designated hole for that particular hydraulic line, so I did and got a good dousing of hydraulic fluid in the process. Once the pump was out, I could see that the line was under quite a bind, and as I readjusted it, the rest of the snap ring fell off of it. Bingo.
As it turns out, this is the main supply line for the servos, and when it got blown out of place, there was no hydraulic oil reaching the servos. Because they lacked the necessary oil to work properly, the piston was stuck in reverse just like a bad line from a vaigra ad. (Thanks KTM!)
This was the problem all along. It's unfortunate that I'd already blown a wad on the new piston, but since the old one was scarred, I couldn't feel good about putting it back in and having to go through this all again in 6 months. Sometimes it costs a little bit extra, but it's better in the long run.
After a complete circus act trying to find a replacement snap ring and seal that took 3 trips to town at a 60 mile round trip every time, we finally found the right snap ring. From there it took me about 10 minutes to fix the problem, another 20 to put the pump and inspection plate back on, and then another few minutes to re-fill all the hydraulic fluid. The only thing left was to fire it up and see if the problem was fixed.
Whenever you fix something yourself, or build it, you always wonder if you did it right and if it's going to work. It doesn't matter how many times I do something, I never get over this trepidation. I think that's a good thing.
I climbed into the cab and started it up. Now was the moment of truth. I reached hesitantly for the shifter and gently eased it into forward. Nothing happened. While that might not seem like a good thing, at least it wasn't going in reverse, so I was making progress. Hmmm... perhaps the oil just needed a chance to purge all the air from the lines, so I eased it even further forward. Much to my glee the wheel moved in the right direction, and then picked up speed and everything began to work just like it was supposed to. It went forward slowly... it went forward quickly... it went into reverse slowly... and it went into reverse quickly. Shoot, it even stopped when it should. *Whew*
All that was left was for us to put all of the shields and insulation back in place, which took another couple of hours, and then let the jack out from under the tractor and give it a field test. Everything worked as well as it could.
*sniff* I just love a happy ending...