trans.leak

[novafrog]

I have a 700 trans.when i drive it ,it don't leak,but after it set's a week or two it leaks bad,the the fluid drips off the u-joint ,not around seal ,where do you guys think its coming from ,could it be a crack in the yoke ,thanks for any help

[Redneck Rydes]

Could be 1 of 2 things,mine started to leak at the speed sensor and on some of the trans yokes had a pressed in plug in the back of the yoke,could be leaking from there

[sick472]

I would still suspect the seal as I have never heard of a yoke that leaks even though I follow your logic . Rear seals are pretty easy and cheap to replace and while your are at it you could inspect the yoke for cracks and leaks. It's a popular technique to check heads/valves for leaks with a paint thinner. I would clean the yoke whiles its out of the tranny real good with brake cleaner and then set the yoke on the bench so that the slip section is pointing straight up and fill it with thinner and see if it migrates out to the u-joint. If tranny fluid gets thought the potential crack, thinner will come through pretty quick. With the yoke good and dry prior to filling with thinner, a leak will show up as a wet spot that grow until evaporation of the thinner takes over. If it's bad enough it may even drip or run. Inspect your seal for damage at the top. Maybe, the seal is leaking high enough to run down the yoke instead of down the seal although I doubt the fluid is really very high on the seal.

[RodnRudy]

I had the same thing happen to me on a street rod I had a few years back. It was leaking out of the rear of the front drive shaft yoke. I cleaned the plug on the back of the yoke, applied RTV sealer around it and that solved the problem.

[Redneck Rydes]

On the rear yoke there is a small pinhole to relieve pressure when the yoke slides in and out of the trans,mostly on pick ups,there was a O ring in there that goes bad,do like RodnRudy says,clean up real good with carb or brake clean, dab a little silicone on a small screw driver and press it in there,should work

[novafrog]

thank guys i will clean it up ,check the plug and fill it with thinner check it for leaks and get new seal maybe that will fix it, again thanks guys

[demian5]

Clean it good and drive it and pinpoint it. How about some pictures?

[1969 Project]

Originally Posted by demian5

Clean it good and drive it and pinpoint it. How about some pictures?

I like that one

[Steeveedee]

If it turns out to be the seal, be sure to replace the bushing(s) in front of it. Even if it just a hard seal, you should replace the bushing(s) as a matter of course. If it turns out to be the bushing(s), you will have eliminated them as the cause. Any time I ever replaced a rear seal, I put in bushings. It is usually worn bushings that cause the leak.

[toolboxchev]

Originally Posted by 1969 Project

I like that one

Heehe! We will beat that problem like sumo wrestler does.

Rear yoke seal.

[Stocker]

Another possibility -- maybe -- is a bad o-ring on the dipstick tube. My TH350 did that and it was hard to track down because the ATF travels so much. Didn't leak when driving (that I could tell) but always left fluid on the ground when parked for several days.

[demian5]

Originally Posted by Stocker

Another possibility -- maybe -- is a bad o-ring on the dipstick tube. My TH350 did that and it was hard to track down because the ATF travels so much. Didn't leak when driving (that I could tell) but always left fluid on the ground when parked for several days.

I had the same thing, thought it was vacuum modulator, replaced it, still leaked. Ended up being dipstick O-ring. And it's nothing special, just an O-ring.