Which came first, the dirty exterior of the transaxle case or the leaking oil?

I would assume the leaking oil. If the oil didnt leak the dirt would'nt have anything to stick to.

Your tractor does NOT have the K46 in it. It has the T40 unit, which is similarly housed like a K46 but is different internaly. It is a sealed unit, so most likely you drained the oil out of the vent tube. The specs for the T40 are not found on TuffTorq's site, but I would guess that the oil capacity is similar to the K46.

If oil is coming out the vent, the transmission overheated (oil expanded beyond normal and purged out the vent). That likely left you low in oil, causing the transmission to overheat easier the next time.

A good oil change to a quality hydraulic fluid or 5w-50 syn engine oil might save it.

My unit has k46 cast into it. Also, are you calling the filler hole with the rubber plug the "vent"? This would be the only openning on my unit. Can you explain?

K46?? Unless it has a K46 housing, it SHOULD be a T40. And T40's have I believe a vent tube. I will look at my 100 series 115 (somewhat similar to yours) to be sure.

A T40 will still have "K46" cast into the housing. The only way to tell the difference is by the white serial number sticker on the back of the axle.

On top of the transmission there are two things, a round black "cap" and a smaller black breather. The breather is sort of a soft rubber. That is where I'm guessing the oil came out of. You add oil via the cap, which you can pry out. Fill to .5" from the top.

Serial number on tag is 40A-0076047. And this number JD PP PN:AM134125. Does this confirm it is a T40? Im going to refill with Castrol Syntech 5W-50 synthetic. This should handle the heat. I would like to thank you guys for the info. I hope I can bring it back to life. Thanks Bruce

I believe that 40A part means its a T40. I wish you good luck in fixing your mower. Oh, and if you find the time, could you please give a follow up?? Thanks. Oh, a little off, but I thank engine_tech for clarifying something I did not know.

I filled the transaxle with 5w-50 Syntec and put everything back together last night. Works great. No unusual noises or klunks. Thanks to all who commented. Bruce

Big Shark,

I have ran into the same issue you original post talks about. My K64 has oil on it, it sounds like a power steering pump on a car when it is low on power steering fluid. The mower has lost power going up hills, and the longer it runs the worse this gets.

I found on mine that the oil came from a cap that fits into the casing towards the front of the mower from the rubber capped vent. The cap that was in this hole, fits very loose. I'm able to stick my finger in the hole where this cap is and hook my finder feeling into the case. The cap here is shaped like a quarter with a couple of slots cut in it, with another quarter welded to it perpendicularl. The section with the slots face down into the opening.

My questions is what goes in the hole over the double quarter shaped cap? There has to be something, other wise dirt could just pour right in.

After you filled yours with the 5w-50, is it still doing well? If so I will fill mine with the same thing. I will probably fill it, run it, drain it, and re-fill it a few times; I image it has some dirt in it.

Re: Refilling with synthetic 5W-50 oil:
I replaced the input shaft last year on my Tuff-Torq K51. At the recommendation of the tech who helped me order the parts, I refilled it with synthetic 5W-50 (Castrol). He advised this is the standard fill in most of their units now. I haven't noticed much difference in performance with the exception that it seems to run cooler. It is reassuring to know there's a high performance synthetic oil in the unit when I'm towing my heavy core-aerator around the yard.