Transmission Leaks - Does the stop-leak stuff work?

[392 Cuda]

Has anyone tried transmission stop-leak (like Bar's Leaks brand)?
- Does it work?
- Could it cause any damage?

It seems like I am fighting a losing battle with my 727... No matter how many gaskets I replace, it leaks on the floor like a defiant puppy... Now it seems it leaks from every port on the transmission (Even the square adjustment screw).

I think I'll eventually swap to a 5-speed, but would like to drive the 727 a bit first.

[Cuda Cody]

I've had great luck with 727's not leaking.  That sucks yours is leaking.

[JonH]

Yes and no. Those products are designed to stop leaks from rubber seals/o rings. Seals dry out when the vehicle isn't driven frequently. That product is designed to rejuvenate and swell the seal to stop the leak. So yes it can work in some instances. It will not fix a leaky pan gasket however, and it will not hurt the trans. Try it, you are only out the cost of the product.

[kawahonda]

My 727 leaked only from the shifter input area. I got it fixed properly by having the tranny shop just do a quick rebuild and replace the seal up through the pan area.

In my experience of using Bar's and the really expensive 3-phase $80 solution on the coolant system is that it has never worked for me. On a coolant system, I'm 0-3 for "Bars" or with the really expensive 3-system that I forgotten the name of,

Sorry, can't be of much help no tranny fluid stuff. I'd be very cautious of using any stop leak for tranny...there's some small passages that need to remain clear and open. I know exactly how you feel though because tranny fluid sucks. It's thick, harder to wipe up, and it stinks.

[392 Cuda]

Thanks guys!

I'll give it a shot this weekend, along with a new $25 LubeLocker gasket and a roll of silicone tape I just ordered.

Hopefully some combination of those will fix it for the summer... Least fun part of the hobby, and my least favorite auto fluid.

[blown motor]

@392 Cuda  Some good discussion here.

https://forum.e-bodies.org/engine-transmission-and-rear-end/4/argh-oil-leak/4562/msg65163#msg65163