[dv657172]

I have been chasing a transmission fluid leak and after replacing two gaskets and a bunch of rtv I think I have found the leak. The trans tube where it enters to trans housing.

Engine is a 68 400 with a TH400

Where should trans tube bracket attach to engine? Current tube bracket has been modified to connect to top right bell housing bolt (not my doing)

Also there is a gasket on the trans where the tube goes into the trans but no o-ring on the bottom of the tube below the lip. Should it have both?

Thanks
DV

[grivera]

The bracket attaches to one of the bell housing bolts. Sometimes, the bottom of the tube will split and cause a mess that no o-ring can fix so make sure you inspect carefully. If it isn’t split, use the “top hat” seal instead of an o-ring and you will have no leaks.https://www.autozone.com/external-en...B&gclsrc=aw.ds

[dv657172]

Thanks grivera!

[b-man]

To use the top hat seal you need to cut off the bottom of the tube and weld on the piece that accepts the top hat seal. They sell kits with the seal and bottom tube section to do this.

Unfortunately it’s not as simple as replacing the o-ring with a top hat seal.

[Sirrotica]

From experience, that area that the O ring seats in, the indented area is where they crack, and as Will has already said, there is no seal that will fix the leak.

In the past I have located the leak, and welded the tube up on the crack, probably not feasible if you have limited welding experience. I learned to oxy/acetylene weld when I was about 16 YO, and that's how I repaired the transmission tubes. Mig or tig would probably work as well. Working with light gauge metal requires some experience to not burn through it, yet penetrate the parent material.

Most people just buy another tube, but if you have something that the aftermarket doesn't make replacements for, welding may be the answer.

[Scott Thelander]

On another note I have found several early 6768 turbo 400 tubes like to crack at the O-ring from thin metal during manufacturing pull the O-ring off and hold the tube up to the light or pressurize the tube and listen for air leaking

[dv657172]

Thanks for all the info. I am likely going to go with an aftermarket replacement as the car is a dedicated drag car and I need to insure no leaks as best I can. Going to try one from Allstar (AAF-ALL69113)

[Sirrotica]

I hope an aftermarket one works, but many won't clear obstructions on the firewall, the exact reason I have welded up the O ring area in the past.

Once the crack is welded, it never leaks again. The 69 GP dirt track car in my signature pics was welded, (T 400) because I couldn't easily find that tube, so repairing it was the easiest way out.

Your car, and your choice.

[grivera]

Originally Posted by b-man

To use the top hat seal you need to cut off the bottom of the tube and weld on the piece that accepts the top hat seal. They sell kits with the seal and bottom tube section to do this.

Unfortunately it’s not as simple as replacing the o-ring with a top hat seal.

I didn’t realize this - thanks for the insight