how to oil change in the hydro trans?

[2fast4u]

I have a yt6700 and a yt 6800 mowers and can't find out how to change the oil in the hydro, trans , I can,t find a drain plug. Owners manuel has no info!  What type of oil should I use, Thanks

[Meofouse]

There is a thread on this forum that I started early last summer with pictures included. I rebuilt the hydro on my YT6700 because of lack of maintenance by the previous owner. There is no drain plug in the hydro to drain the old oil but there are two ways to drain it if you are somewhat mechanical inclined. The first and easiest way would be to remove the filler cup that attaches to the unit and using a small syringe and small tube try to suck out the oil. You will find that this doesn't work very well and will not get all the gunk and dirt accumlated on the inside bottom. The second way is to raise the tractor so you can access the hydro. If you remove the rear tire on the side where you pull the lift lever for hydro neutral you can see where the lift lever actuates a small button on the hydro. This button actually opens a passage that allows the oil to flow freely in the unit to prevent damage if you need to move the tractor without the engine running. Be that as it may, the button is held in place by a hex nut. Loosen and remove the hex nut around the button... be careful there is a small spring in the unit, do not lose it! The oil will drain out. If you can, flush the unit with kerosene or something to remove the sediment, blow the unit out with an airhose and replace the spring/button nut/lever. The book calls for regular 10W/30 motor oil but I put a straight 40 weight in, it improves performance on the older unit and adds better wear protection. The units can be repaired with some t-l-c and luck finding parts.
I am just a shade tree mech and if I can do it just about anyone can. If you need I can take some pictures of the area where you need to work.
Hope this helps,
Cal

[Meofouse]

Here is the link to the forum string concerning the 6700 hydro.
http://www.nabble.com/YT6700-transmission-td23788827.html

[RAB5050]

I found mine after pulling the rear deck and a good cleaning. Actually I took my best guess by scoping out every nut head and bolt, got lucky the first try. It was an Allen bolt facing toward the rear and it was right near the bottom left hand corner if I remember right.
 (some where on this site is a link to the owners manuals)
RB

[2fast4u]

 Rab5050, Thanks for the tip, Do you have any additional info or picture of this exact bolt to remove to drain the oil, Thanks again for the reply!

[RAB5050]

 I hope this will help, also the refill for the differential is that rubber tube at the top of the caseing.
RB

[2fast4u]

My yt6700 has a resevor at the top to fill the hydro with oil , It doesn't have a tube like yours, what model do you have, Thanks