Solve the TH400 LEAK!

[CB1987]

To begin with I am new to this board as well as the mechanical arts. Although I am phenomenal at carpentry it did not surprise me that it didn't transition into this truck I purchased.

I recently bought a 1968 GMC 2500 non-matching 350 and TH400 transmission. During my search for a vehicle I noticed everyone here loves to see shots of the truck so I attached one to fill that need. Mechanically the truck is pretty good with little things to buff out, no big deal it will be a good learning experience. Initially the transmission pan was leaking...so I replaced the gasket and it was fixed. As happy as I was about successfully completing this without professional or Google assistance, it did not last long. I have no idea what these parts are called so attached are photos. There are slight leaks in these locations. I would hate to bring it to someone to get fixed but I am at the verge of it because I need to for work in 10 days! Is there any easy fix for this that I haven't been able to find?

Remember I know nothing in this field but if it is needed I can take verbal abuse pretty well! Thanks for the help.

I wasn't able to upload them directly but here is the 1st leak.
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http://desmond.imageshack.us/Himg543...pg&res=landing

I tightened it up, the leak went away and came back after an hour or so of drive time. After I tightened it again it never went away.
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http://desmond.imageshack.us/Himg26/...pg&res=landing

Yea loosened or tightened still leaks a little. I can tell the previous owner tightened it too much because around the threads there are little dents where I think it might be leaking. Is there some sort of silicon I can put in there?
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http://desmond.imageshack.us/Himg840...pg&res=landing

This one is the worst of the three. Drips about once every 20-30 seconds. I looked up what I could and found what i thought was a solution. I removed that bolt holding the lever on and put in a generic rubber seal. It worked a little bit but didn't stop it completely.
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http://desmond.imageshack.us/Himg36/...pg&res=landing

There is a shot of the side, not the best but the best one I have on my computer. Thanks for any help you all might have. If there is any more information you need just let me know! Also, if you can give me a brief description of what the 1st and 3rd parts are would be appreciated.

[Roninwolf]

pic one is speedometer cable to gear housing needs seal and o-ring, pic 2 is drain plug need new plastic or copper washer,pic 3 is shifter arm has to have right size seal or o-ring.

[CB1987]

Do you know the right size seal and o-ring for the speedometer cable? Or the right size for the shifter arm? Is there any resource available that explains how to replace these or is it pretty self explanatory after I take things apart?

[70cst]

I have a Th400 and it leaks a little also. I was told that it's important to keep the truck running as it helps keeps the seals working properly. Long spells without driving the truck is hard on seals. I might be wrong so I'll sit back and let other chime in...

Good Luck.

Oh yes...

Hey CB1987 ...

to the forums and from Ohio.

[SS Tim]

Roninwolf has it right. The first two are real straight forward to replace. Of course the fluid will drain out while you are getting a seal for the bolt. The last is the trans, sector shaft seal and it is easy to replace "with the right tools". Otherwise you need to drop the pan and pull stuff apart you may not want to. It is a speciality tool that is going to be hard to find in the Oxnard area on a weekend. For everything including a tool try NAPA. Might just print the picture and take it with you.

Now a couple of thngs come to mind.
Is the trans. fluid level correct? Checked hot with the engine running.
Is the flange on the trans. pan flat. Often people replace the gasket and tighten it too much. The bolt holes then cone up preventing a good seal. Anytime the pan is off make sure the area around each hole is flat. Might need to take a small ball peen hammer to them on a flat backup.

[SS Tim]

Here, the tool looks like this. Go to NAPA's site and look around. Found this link looking for a quick tool picture as well.
http://www.jeep-cj.com/forums/f2/hel...10/index2.html

Gotta go take some dogs out, burning moonlight.

[bollybib]

Here is something that might help you with the speedometer cable leak. I got my seal online, but you may be able to get it at a local transmission shop.

http://67-72chevytrucks.com/vboard/s...6&postcount=14

http://67-72chevytrucks.com/vboard/s...8&postcount=15

[GASoline71]

Just remember... if a 1st gen SBC or TH350/400 ain't leakin'... it's out of oil!

Gary