312A Transmission Oil Question

[flyncasafo 0]

I have a 312A Hydrostatic Drive Unit that I got from the previous home owner. It has about 1000 hours on it. I love the tractor.

I was mowing yesterday in the heat. The tractor did fine for about 2 hours. Then I was going up hill and the tractor was slowing down to a crawl. I took it to the garage and saw that there was a ton of clippings around the cooling fins of the transmission. So, I started cleaning. I ended up taking the seat and fenders off, cleaning the entire back end. I also drained the old tranmission fluid. I added a little fluid to the resivor and it will not drain in. So how do I get the fluid to go in? The manual says to use 20W oil and it only takes 3/4 of a quart.

Thanks

[CasualObserver 3,406]

:whistle: I don't have an answer for you, I just wanted to welcome you. I'm a gear drive guy, hydros are voodoo to me... but others will be along shortly with an answer to your question.

[TT-(Moderator) 1,129]

The 312A models use an Eaton model 7 hydro unit that is separate from the transaxle.

Changing the oil in the hydro unit is not recommended, except for major service (but it's old enough now that it won't hurt.) The hydro unit requres 3/4 of a quart of S.A.E. 20 oil and when full, the level should be approximately 1 3/4" below the top of the reservoir. (the off-white reservoir with the black plastic cap, located under the rear fender.)

I'm guessing you have drained the oil from the transaxle. (through the hole with the pipe plug -- on the very bottom)

Refill through the dipstick tube under the seat with roughly 3 quarts of 10W-30 or 10W-40 motor oil. (until the level is between the "L" and "F" marks on the dipstick)

Do not exceed the full mark!

[flyncasafo 0]

It was not the transaxle. I know which one you are speaking of, but I did do the transmission pump.

The fluid in the transaxle looks good.

Does the engine need to be running to get the oil to go in? Is there some trick that I need to be doing?

Thanks

[TT-(Moderator) 1,129]

:whistle: I owned a 312A for about 5 years and never tampered with the hydro oil.

I would think that starting the engine and running it at idle for a brief period would draw the oil in to the pump. If the oil level doesn't drop, shut the engine off immediately.

[flyncasafo 0]

Thanks TT, I did start it and nothing happened. I am afraid the pump is shot.

Maybe someone else can help that has done this.

Thanks

[TT-(Moderator) 1,129]

Do you still have the seat & fender removed?

My Eaton manual shows a venting plug on top of the housing on the motor side of the hydro unit.

You'll need to remove that plug and add fluid through the reservoir until it comes out the venting plug hole.

[kj4kicks 151]

Slightly different animals, but both of my 520's and the 416, all have the same issue. Seems to get air-locked, and takes FOREVER to refill the hydro!

$.02.... over and out.

PS. :whistle:

[TT-(Moderator) 1,129]

Eldon -- the model 11 has the same venting plug, so next time you might want to give it a try. :whistle:

[kj4kicks 151]

Eldon -- the model 11 has the same venting plug, so next time you might want to give it a try.

Thanks TT !

I'm such a dork sometimes.... :WRS:

[flyncasafo 0]

Thanks again guys, I will try that now.

[flyncasafo 0]

Gentlemen, we have success! I did not find the venting plug, but I removed the "T" fitting which made a larger hole for the fluid. My son drove it around the yard and we rechecked the fluid and its good.

You gotta be 10% smater than whatever you are working with. Today the tractor was smarter than me.

[TT-(Moderator) 1,129]

:whistle:

So far, so good!

Now you have to give it the "working in the heat" test.

Let us know how it goes.

[TT-(Moderator) 1,129]

Slightly different animals, but both of my 520's and the 416, all have the same issue. Seems to get air-locked, and takes FOREVER to refill the hydro!

Just doing a little more research and realized that the motor side of the housing used on the WH's is turned 90 degrees on the 11's. (from what it shows in my book) Meaning that the venting screw doesn't exist.

They draw and return the oil from the transaxle housing, so the air locking problem must come from the narrow dipstick/fill tube with no other vent in the case. :whistle:

[kpinnc 11,076]

Just another $.02 as well.

The hydro resivior has a "krap trap" screen in the bottom of it. Though I have no idea what the correct method for cleaning it safely would be, they do tend to clog up fairly easy.

Just for future reference...

Kevin