Trunion Shaft Seal Leak?
 

Morning Fellas,

So i just finished the Axel seals and Cork gasket on my 129, for a first time the process was easier than i expected to split the tractor thanks to the thread about that exact issue! So i get her all back together and get her cranked up and notice i have a leak, so i investigate further and find that it is coming from the Trunion rod where it passes into the pump unit. So im kinda at a loss here on where to go and what the next move is... is this repairable? or is this something that will need to be professionally done as i assume the pump will need to be split at this point? Any input is greatly appriciated yall.

Thanks,

Matt

Is it leaking from the left or right side? Left and right based off you sitting on the tractor.

The leak is going to be on the drivers side... left side of the tractor. When its running you can see little bubbles coming from around where the trunion shaft goes inside the pump housing. Shortly thereafter ill have a slow but steady drip once the fluid runs down to the cooling fins.

Matt

The pumps going to have to come apart to replace that seal, if you haven't already you need to download load the manual. I'd also recommend messaging Sam Mac as he's pretty knowledgeable with those pumps.

If you don't have a decent set of tools and a really.... I mean REALLY clean place to work in, I'd suggest having that seal changed by a shop. However, as someone who has done it and worked at dealers before, you may not "get what you pay for" so to speak. Few "mechanics" have pulled hydrostats apart. It's not a overly complicated job, but it does require some skill. If your going to do it yourself, I'd suggest buying and changing all the seals and gaskets on the whole pump. I personally don't suggest this job done by someone with little mechanical experience, just because of the sensitivity of a piston pump. They are similar to, but somewhat more sensitive, to dirt than the inside of a motor/engine.

I cannot agree with John more!
For us who know our way around tools/equipment it is just another walk in the park.
But for those who are a little intimidated with mechanical things, it can turn into a disaster.
Do study the service manual and online videos before you decide one way or the other.

It's not that big a deal to change it. Biggest issue to things need to be CLEAN. Take your time, read the manual, then read the manual again and after you do that read it again. Look at it this way, it was assembled by a human, no reason you can't do it yourself. Take care when driving the pins out of the swash plate especially on the trunnion side. It has 2 pins and you need to be careful to follow the manual or you will be in trouble. Other than that it's not a big deal to do one. Worst case if you screw it up you can find a good used pump on Flea Bay.

Do not try this without following the manual
 

There is a critical step in disassembly where you can ruin your hydro housing if not done correctly, not to say it is a difficult job, but it is a job that has specific steps that must be followed.

Sam Mac beat me to it.

Morning fellas,

Thank yall so much for the replys! I am reasonably mechanically inclined, and have the drive to do it. I have read the manual, and the only tool i dont have is press or vise to press the spring down in the piston barrel to remove the spring retainer. We actually just moved so my garage is really clean at the moment, cluttered with some boxes, but clean. Ill have to get a set of calipers from work so i can accurately measure the slippers. After reading over the manual i think i can do this. Im going to look up some videos on the youtube to get a better grasp on the whole thing as well.

I know the seals and gaskets are avalible through CCS as they have a "rebuild kit" are the barrings avalible through them as well? i dont recall seeing them yesterday.

And when the manual says to clean parts, i assume that means use a sacrificial quart of hytran or fresh hydro fluid?

Thanks again guys! great help!

Matt

WHOA, there cowboy!!

You don't need to rebuild it! I promise, it's in fine shape inside there. No need to buy a press or mic's to measure stuff.... or even borrow them. If the slipper pads are wore, you'll be able to see it with your eyes. They don't just wear a little, they basically don't wear at all unless something goes wrong, then it's usually catastrophic. DO NOT take the springs out of the piston blocks. Just leave them alone. DO NOT take the pistons out of the piston blocks, and be very careful when disassembling to try and keep them from falling out. They need to stay in the same hole if possible. Just order the case gasket, cork gasket, o-ring for the charge pump, O-rings for any of the fittings or for the relief valves if you want to remove and change them, and the seals. No need for bearings, or anything else unless you find something once you get in there. If you do find issues.... weigh your options. Good used hydro's go for between $75 and $125, so no need to spend a bunch of money on one.


Clean the internal parts with diesel fuel, then coat with hytran before assembly. Clean the case and other parts with mineral spirits or lacquer thinner.