Odd tranny leak

[Piece of Work]

I need help diagnosing an odd tranny leak. When I drove it every day, there was no evidence of a leak. If it sits for 2 or more days, it leaks. It's been sitting for 10 days, to take it apart and do some body work, and now has leaked quite a bit. Any ideas what it could be and cost to fix?

Thanks,

-Mark

[kxnomore]

I'll be watching this thread too. Same exact problem. Mine's a Turbo 350 on a 4 X 4.

I can't tell if it's the pan or the rear seal?

[Overkill67]

Check the dipstick tube where it goes into the trans. I have seen that puppy drive guys mad. There is a rubber o-ring at the base of the tube and that may be shrunk or cracked. When the truck sits for extended periods of time fluid starts to drain back into the pan (what would normal remain in the convertor and valve body) and pushes the fluid level up so that it actualy leaks out there. same goes for the vacum modulator if yours is equipped, or possiably the pan.

[Piece of Work]

I hope it's the dipstick o-ring. The tranny was rebuilt prior to my purchasing the truck in Feb. I could use a fix that's easy and cheap!

[Texasdeere]

Don't forget the selector shaft seal too. I think that is where mine is leaking after it sits for a while.

[1968SWBBigBlock]

I learned - at least I think I did something. The instructions on my new converter discussed fluid level at length. The are of the opinion that most trannys are over full. leave the fluid when warm at the bottom of the cross hatched area on your dip stick tube. They seem to indicate much the same as above that the fluid can drain back different amounts based upon in what place the converter stops. Ditto on the Oring - the fit on aftermarket dip sticks is not great to begin with. I have been trying to make an addtional sleeve that would allow an extra level of sealing. I have even thought about going and getting another crimp put into the tube to allow for dual O rings. The factory design leaves some room for improvment!

[Jonce]

I had the exact same problem on my reman'ed TH350 with less than 40 miles on it. It turned out to be the kickdown cable leaking. I was missing the rubber o-ring on the end that fits into the transmission. I went to the transmission shop and was told there are two types of o-rings - one is a standard o-ring and the other is a boot style sleeve (looks like a top hat) o-ring. The transmission guy gave me the o-rings for no cost

I also replaced the cheap chrome B&M tranny pan with drain bolt. I went to the dealer and purchased a completely stock transmission pan with no drain bolt.

Hope this helps.

[raoul.duke]

I'm another one with this problem....I figured that my truck got nervous when I didn't drive her for awhile so she would puke all over the garage floor....

I've replaced the selector seal and the pan gasket....guess the dipstick tube seal and kickdown cable are next.

Does the dipstick tube just pull out of the housing to allow replacement of the seal?

[Lemield]

My CST with a TH350 does the same thing....???? Should the level be checked in neutral or park...or does it matter? I had a 1998 Dodge that was 2 quarts different on the dipstick between neutral and park.

[hootlube]

Dodges check in neutral; CHEVYS (rule) check in park. Fluid should be between the cold and hot, with engine at operating temp. Dipstick tube probably has a tang welded to it that attaches under on of the bell housing bolts, kinda hard to get at. Remove the bolt, tube just pulls out. Replace O-ring, remember to smear some fluid on it so it goes in without binding. Luck.

[Olden Days]

Originally Posted by TexasC10

Don't forget the selector shaft seal too. I think that is where mine is leaking after it sits for a while.

This is a common one that a lot of people overlook or mis diagnose it for a pan gasket leak. My th400 is leaking from there right now and it is very irratic. It will go for awhile without leaking (much) and then all of a sudden decide to dump a bunch.

About the dipstick tube. You guys with leaks there ought to go get the updated version (tube) that uses a big boot seal instead of the o ring. That o ring can break too easy.

[mexgrhd68]

Originally Posted by Piece of Work

I need help diagnosing an odd tranny leak. When I drove it every day, there was no evidence of a leak. If it sits for 2 or more days, it leaks. It's been sitting for 10 days, to take it apart and do some body work, and now has leaked quite a bit. Any ideas what it could be and cost to fix?

Thanks,

-Mark

how about your speedo cable? mine was leaking from there, my tranny guy just gave me two little seals that go in there, you only need one, but he told me to double up on it and it should stop, guess what?? IT DID