727 leak -what’s this?

[Car #4]

This leak is from the back side of the transmission body. The bolt head is bolting the tail section to the main body and the leak is at that found thing just below. What’s the round thing and what’s the fix?

 

[4406bbl]

Change the o-ring on that shaft, you have to slide the tail housing back, pull the pan, and slide the shaft out. Get a service manual, easy in car fix.

 

[dadsbee]

Rear servo pivot shaft. You need to "waste" more time here... I covered this last week! LOL Many, as I did, miss this thinking they have a shifter shaft or pan leak.

https://www.forbbodiesonly.com/mopa...our-mopar-today.20805/page-466#post-912211356

The only other option is to pull the rear case ( or turn it clockwise), or cut the retainer tab off and replace it with a fabricated metal tab to retain the pin. Pin has 2 O rings on it, I believe, if you want to drop the pan, valve body and remove the pin to change the O rings.

 

[493 Mike]

Tap the reverse band anchor pin into the case as far as you can (gently), spray the recess clean and when dry, fill with silicone sealant. Old DVW tip!
Mike

 

[dadsbee]

If you follow how I did it in the link... you need to drain the fluid out or it will seep before your sealer cures and continue to weep. No drain plug in the pan, no big deal. Find some aquarium air line tubing and stick it down the dipstick tube and siphon the fluid out.

 

[Car #4]

Thanks for the replies guys. @dadsbee I did think it was a pan leak. I changed the gasket, to no avail of course. What did you use for sealant?

 

[pnora]

My take. Fix it right. Its not that hard of a job.

 

[dadsbee]

You've got to get it SPOTLESS... first !

 

[4406bbl]

Here is a pic. With that o-ring leaking I would bet the shift shaft seals are next.

 

[dadsbee]

What did you use for sealant?

As shown in the link I provided, but you won't want to buy a can at $225 a pint! Good gasket maker or RTV will work if you let it cure.

 

[dadsbee]

Its not that hard of a job.

Nope, but not something you really want to do after you've just done every other seal and a new pan gasket only to find the pivot shaft was the main culprit. I certainly wasn't tearing mine apart again with nothing else now leaking.

 

[MoparGuy68]

I think I have the same leak.. There currently is some red stuff over that area. Looks like maybe someone tried to stop a leak there, with the red stuff, at some time in the past..

I installed a new cast aluminum pan and gasket almost a year ago. The old stamped steel pan and cork gasket was definitely leaking badly. Prior to the change, I could watch it drip off the pan onto the ground while the engine was running.

After installing the new pan the leaking was significantly reduced to where I could not watch it drip on the ground anymore. But, ever since, I still get drips appearing on the bottom of my new pan within about 24 hours after wiping it clean with a rag (with the car sitting, not even running the engine).

Unfortunately, the TCI pan’s drain plug leaks and I still think I’m getting some leaking past the pan gasket, just not nearly as bad as it was with the old stamped steel pan.

 

[dvw]

I personally use Ultra Grey RTV. I apply it to every build I do over the band anchor pin. Even with a new o ring. Not all RTV works with trans fluid either.
Doug

 

[Car #4]

I bought the truck last fall and haven't really driven it. I'm thinking I might take it to a tranny shop and have it gone over. The guy that owns the shop is a Mopar guy and he rebuilt my 904 several years ago. I'm suspicious of a leak where the shifter goes in also. I don't understand automatic transmissions much so maybe I'm best to let him go through and get everything right. That way I'm good to go with confidence.
I do appreciate everyone's input.

 

[Car #4]

@dvw Would Ultra black work? I’m thinking it should.

 

[zyzzyx]

I'm putting my 727 together right now, and have been reading that this pin is a problem always!
I took the pin and machined another O-ring groove next to the original one and bought two Nitrile
O-rings for it. Then cleaned everything squeeky clean with brake cleaner and put a dab of Ultra black
over the top of the pin as shown earlier. Alot of B.S to go through, but I HATE leaks!

 

[pnora]

I'm putting my 727 together right now, and have been reading that this pin is a problem always!
I took the pin and machined another O-ring groove next to the original one and bought two Nitrile
O-rings for it. Then cleaned everything squeeky clean with brake cleaner and put a dab of Ultra black
over the top of the pin as shown earlier. Alot of B.S to go through, but I HATE leaks!

Some shafts have two grooves for the O-rings.

 

[493 Mike]

Some shafts have two grooves for the O-rings.

Ma Mopar still only put one O-ring on though. The O-ring just gets hard with age, causing the leak. One fresh O-ring has never failed me in 50 years of building TFs.
Mike

 

[dvw]

A new O ring and RTV. It won't leak. I've built about 30 727s in the last year and half. No leaks.
Doug