X500/K72 Tuff Torque leak up high---gas tank removal

[al3]

2015 Tuff Torque K72 in a Deere X500 that began to leak transmission fluid; drips on cardboard after mowing. Not a lot; 1 ring the size of a silver dollar or so. After a few cleaning/mow/examine cycles it would appear source of leak is the input shaft seal. Don't know for sure, but its coming from high on the upper case. Have verified the transmission fluid reservoir o-riings/grommet is not the source---too bad, easier fix.

Hoping I could pull the seat/fender assembly/gas tank to gain access to the shaft/drive pulley/fan assembly. Seems like a better approach then removing the entire transaxle.

Anyone remove a gas tank and can report how long it took?

Also thinking I could pull the old seal using the sheet metal screw in the side trick.

Anyone replace the upper seal in a K72 this way with success?



Thanks

 

[tomplum]

The tank removal is pretty quick and easy. There are 2 bolts (13MM heads) on each side that attach the seat platform to the lower body and you will see them underneath at the back of the foot pads. On top the two 10MM headed bolts. Undo the fuel cap and stretch a nitril glove over the outlet to keep dirt out. Unhook the seat switch harness and pull it through the body to lift off. The tank normally will just / lift twist out one it is unhooked. Sometimes the support rest under the neck- like a long bolt has to come out, sometimes not.

It's a great time also to filter your fuel out of the tank and clean things up.

 

[al3]

Appreciate the reply Mr Plum. Sounds pretty straightforward; hopefully will give pretty clear access to the upper case components. Good idea about cleaning the dregs from the tank, too.

 

[al3]

Finally getting to this; good winter project.



Turns out it isn’t the shaft end seal, rather the small (1 3/8 dia or so) rubber plug located on the cases’ top side. (see red pen tip) Rubber is cracked, fluid had the appearance of oozing from the cracks, but at 20 degrees not a lot of oozing to be done, at least quickly. Seems like an odd design for a plug.....

Looked at both JD and Tuff Torque site. From pictures of the replacement parts I’m assuming its a press in? Anyone replace and use either the Deere or TT part and care to evaluate?



Access was indeed pretty straightforward. Bolts/seat switch harness removed as suggested above. For anyone else doing this, you’ll need to unload the drive belt tension by removing its spring. Impact wrench on fan nut will release it and the pulley. Also need to remove two fuel hoses from tank fittings.

 

[tomplum]

That's the official fill plug. It will just pop out with a sharp chisel. Underneath may be a magnet that when lifted out could point to the overall health of your T/A. This would be a great time to change the fluid. Tuff Torq has an updated fluid recommendation. I use 15W50 synthetic, dunno if you you do snow work with this if they still recommend low vis. or not.

 

[dstig1]

You find the part yet?

 

[dadohead]

Use Low Viscosity Hygard for the HST.

One important step in the re-assembly is greasing the input shaft splines! (prolly too late for OP being Sept) The input sheave/shaft joint will 'fret' (micro-motions that create the characteristic red oxides that erode the joint). The factory applies grease to the splines to slow their growth. If not serviced, the input sheave will fret and eventually strip out at about 400 hrs (it is softer than the transaxle shaft). I re-grease this input shaft every 200hrs at the transaxle oil service.... some fretting is present then.

 

[al3]

I’m equal distance (35miles) from two Deere dealers, both had item in stock and picked up yesterday. Need to clean outer cases before removing the old plug.

When disassembling noticed the input pulley had provision to attach a puller (two 180 degree spaced threaded holes) but none was needed. Will take a close look at condition of input shaft teeth, thanks. Unit has about 170 hour.

Interesting design with the expansion tank located above the transmission. Would seem to guarantee a leak/seep if the plug cracks like this one did, at least if the expansion tank is filled above the minimum line. When previously changing the transmission fluid I re filled thru the expansion tank; thus the original plug aged to the point of plastic failure. Looks like that was a bad plan......

 

[Spindifferent]

For future reference, here's another post from a different site regarding the issue:

https://www.mytractorforum.com/threads/x530-transmission-fluid-leak-update.1321515/page-2

I'm bookmarking this thread for my X584 should it ever have the plug leak. I did have to replace the expansion tank as it cracked and then leaked. Not sure to blame Deere or TuffTorque for the poor quality materials...

Good luck with the repair!

 

[dadohead]

I was senior engineer at JD and had responsibility for transaxle before retirement. The K72 was bought complete with overflow bottle and came pre-filled. Tuff Torque owned that design. The K71 before it came without. JD owned the bottle design, installed, and filled the system on the JD line.

BTW- The reservoir provides the necessary pressure head to the pump. From memory, the HST has several internal 'tanks' that are independent of each other. The plugged hole and reservoir hole are used to initially fill the transaxle. This ensures both internal tanks are filled properly before assembly line testing. Hope this helps!