IH Farmall 350 transmission fluid change

Hoping to get a little help. My uncles asked me to help them with their 350. It is a 1957 350 row crop with TA. It appears they had not changed the tranny fluid in 20+ years. As a result, enough water has accumulated in the tranny. It froze up this past weekend to the point where it would not drive. Obviously a significant amount of water. Unfortunately the tractor was parked in the woods, about 6 miles from the barn. I spent about 3 hours yesterday with heaters under the tractor thawing out the tranny. Was able to get it home and in the barn where I can work on it.

I know there are 3 drain locations on the tranny. I spotted a couple of them quickly yesterday while under the tractor. I noticed the one about mid frame on the tractor requires a square drive socket to remove. Could someone tell me what size that is? I had assumed it was a standard 1/2" or 3/8", but that is not the case here. This drain is at about the lowest point on the tranny. Actually part of a narrow plate I believe. I also have no identified the correct place to fill he tranny with hytran once I have it drained. I believe I am looking at 7gal to fill it. Would appreciate confirmation of that too.

I would appreciate any suggestions or lessons learned in the fluid change. Obviously I have never done one on this tractor. Just want to make sure I don't overlook anything. I wanted to take a few days to gather info before I head back out to the farm and work on it. I appreciate any help you guys can provide.

Drake9898

hytran or equal-- I don't know the exact amount but its more than 10 gallons. The fill hole is the three bolt plate to the right of the shifter.
There are plugs on the left side of the tranny fill till it comes out the lower hole. The water is either condensation or its getting in around the recessed bolts that hold the transmission cover on.

A 1/2 or 3/8 wont fit? It will be loose,not a tight/perfect fit. If that still wont work,find a piece of square stock and grind to fit,then use a crescent wrench to turn. What size? Grab a ruler and find out.Be sure to did all the 'crap' out of the square hole.

5/16 on the recessed plug. They can be real tight so I cut off a good grade 3/4 or 5/8 bolt and ground and filed a square the correct size on the end to try and not twist in two. Then use a wrench on the head.
May also want to change the PTO oil also.
Good bit of oil will still be trapped in after draining at the three places. Chances are the new oil will turn milky after running. Some have filtered and heated the old oil to burn off the moisture then putting it back and running a short time before draining again. Repeat as needed until it gets better, then put new in.
Some put diesel or other in and run a short time. Don't like to do that on those myself because the amount of fluid trapped in the T/A cavity, above the T shaped plate on the bottom of center housing and other places. If you have the means to raise the front of tractor near straight up for 5 minutes a good percent of the trapped oil will go to the rear.

More than likely the plug will turn out fairly easy with a good fitting ground down tool. If it does not want to come out, to avoid stripping it out, I make the tool long enough to put a pipe wrench on it. Then I put a bottle jack on the tool to hold it very tightly in place and put the pipe wrench on. I have got a lot of really tight plugs out that way. When I worked at John Deere dealer, those boys heated the plug but that always gave me the willies with oil in there.

Thank you all responses and suggestions. Sorry for my delay in response. Things have been really hectic on my end. My uncles keep this tractor outside the majority of the time. I am quite certain that the water issue is both a combination of seepage and condensation. Like I posted earlier, I know they have not changed the fluid in 25 years. Now it is just a matter of getting back out and working on it. I parked it in our barn where I can work on it. There are several other maintenance items they have been ignoring that I would like to take care of while it is idle. I did manage to get my hands on a 5/16 4pt impact socket that will fit on my 1/2" breaker bar. I am hopeful that will remove the plugs when I drain the fluid, if not, I make one as suggested by a few. This tractor has been an amazing tool for us. I hope to keep her running for many years to come.

The next thing on my list to look at after this is the clutch. She has been hanging up and not wanting to shift back out of gear when the tractor is under a load (pulling). Have not had a chance to dig into that one yet. Not sure if it is a clutch issue or something else yet. It typically takes some double clutching to get it to come out of gear.

Thanks again to all.

The first thing I do when I get ready to remove a pipe plug is take my 2 lb. hammer and give the plug a couple good wacks. It's surprising how it helps.

Moving onto your clutch not releasing, I bet if you pull the TA lever back you can then shift gears. Your clutch & TA linkage needs to be readjusted. When you push the clutch pedal in you have to release both clutches (Main & TA clutch)
Take a look at your manual and adjust away. I'm sure your problem will go away.

Charlieu- It is interesting that you mention the TA out of adjustment. I noticed the TA linkages were was out of adjustment when I looked at it the other day, but did not think the two would be related. I know there is a Youtube video out there that I watched a week or two back on how to adjust the linkages. I will re-adjust the linkages and see if that fixes the problems. Really appreciate the response.