Smoking mystery marvel

Brian, Check your swash plate O rings. Most of the time these O rings crack and start leaking. It is very hard to tell where its coming from even if you wash the trans down. I replaced my O rings and had no leak for about a month. Then developed another leak. Turns out my dipstick tube was loose and leaking out past O ring. Replaced and haven't had a leak in 6 months.

Hi Kevin,

Thank-you!

What/where is/are the swash plate?

Again, the fluid is a clear, yellowish fluid...hydralic fluid?

You are right in that it is hard to locate the leak as I cleaned the tractor up and still could not discern where the leak was coming from.

Is the swash plate "O" ring a bigger job?

Coincidently, I replaced my dipstick tube last fall.

Thank-you again.

The John Deere Low Vis Hygard trans fluid is a golden or yellow color, so this is what you are seeing. The swash plate O rings are located at the end of your speed control shaft, well on the shaft that connects to the speed control. Just follow your foot pedal that makes the tractor go forward and reverse back to where it connects to the shaft coming out of the trans. and under the bolt and washer are 2 O rings. You will need a small pick to get the O rings out. Also will need snap ring pliers. I have a set with right angle jaws which makes it much easier to get the snap ring out. Some people have done the work with the trans in place. There is a hole in the side of the frame to fish a socket and extention thru to take the bolt out. I partially took out the trans from the frame. I unbolted everything that connect to the frame or was in the road, but left the drive shaft connected. I then jacked the frame up so the trans would fall down to access it better. After that it was a lot easier to replace the O rings. When you get the O rings out and put the new ones in, make sure you use plenty of vaseoline on the O rings before installing. OH and one last thing you have to drain the hydro fluid before you start. It took me about 2 hours when I did it only because I never did it before. I think a could do it in an hour now. Having a tech manual doesn't hurt either, especially if you get stuck. Good luck.

I have used Marvel as a combustion chamber soak before. I just roll the engine close to TDC, pour in enough to cover the piston, and roll over by hand a couple times to coat the cylinder and valves. Roll back to TDC and cover the piston back over with MMO. I let it soak a few days, MMO is not a fast working solvent.
I once did a little experiment, I had a Kohler K301 I was freshening up a head gasket on. I took the head off, and since I didn't need the tractor anytime soon, I covered the piston and valves with MMO, and let it soak about a week. All the hard carbon deposits could be easily wiped off with your finger. Top of the pistons and valves were as clean as new.
If you are doing it with the head on, go ahead and let it soak as I described, but take the spark plug out and, with some rags over the plug hole, crank the engine over a few times to blow all the remaining MMO out. If you leave the oil in the cylinder, you will hydro lock the engine and not be able to crank it over.
Also change the oil, as whatever seeps by the rings will get in the oil.
If you are to use it in the oil, don't go over the recommended amount. I think its 20% MMO 80% oil. The MMO is pretty thin, and would not properly lubricate an engine at running temps.