What To Use to Seal Transmission Tube To Trans Body

[Fitz98]

I pulled the transmission tube from my 98 Expedition with the 4r100 Tranny.
It is a 2 part tube. The upper part is long and curvy and has an o ring seal on it.
The lower part is an offset elbow that presses into the transmission body.
There is no seal or o-ring where that lower part inserts into the transmission.
That connection is a source of a transmission leak.
What should I use to seal that connection back into the transmission body?
It looks like the last time someone serviced that part they used RTV and Teflon tape, which did not work.

 

[OVERKILL]

Ford Grey RTV, it'll seal that up tighter than a nun's you know what.

 

[Fitz98]

Same one used for rear differential? TA-29

 

[OVERKILL]

TA-31 is the stuff I believe? But the TA-29 should be more than sufficient.

 

[Lubener]

Originally Posted by OVERKILL
Ford Grey RTV, it'll seal that up tighter than a nun's you know what.

 

[CT8]

You will need to have the surfaces that you are going to seal oil free.

 

[P10crew]

Go to your dealer and buy a new one.

 

[kstanf150]

Originally Posted by P10crew
Go to your dealer and buy a new one.


Yep

Going cheap never works for long !

 

[samven]

I dont know for sure but can you check and see if there is a groove cut inside the transmission port for an O ring.Someone may have pulled the tube out and either the Oring disintegrated or was pushed into the tranny as they tried to reinsert the tube.

 

[P10crew]

My experience with those tubes is that they only fit tight once.

 

[4WD]

Originally Posted by P10crew
My experience with those tubes is that they only fit tight once.


Yeah, a zero clearance fit probably means something needs to plastically deform …
Gonna be the thin tube and then it's been necked down.

 

[Fitz98]

Originally Posted by P10crew
My experience with those tubes is that they only fit tight once.

I am not sure I know what you meant by this. I could interpret it to mean the original tube would only fit tight once if it was to be reused, or could mean the hole in the transmission case could get enlarged, so even a new tube would not fit tightly.
I can still see factory cross hatching at the base where it press fits in place and also some areas with factory paint still in tact, so I am assuming the bore in the case may be slightly enlarged. Perhaps partially due to the fact that the dipstick tube was not bolted in place from previous mechanic and vibration worked it loose.
I had one transmission guy tell me he JB Welds the tubes in place when they leak.
Would I be better to JB Weld if the case hole is slightly enlarged to bring it back to a tight fit, or go with the Ford Grey RTV to gasket seal it? Perhaps even hylomar blue?

I will be able to see this from the bottom with the pan removed, so I can be sure that there will be no contamination into the transmission or fluid, and will be able to clean all the surfaces well.

 

[Fitz98]

Ended up buying a new tube from dealer.
It has what appears to be some white Teflon coating painted on (Not the tape kind).

Does this seem like a sufficient seal? Part of me wants to scrape it off and use the Ford Gray RTV instead, but it seems like it must come this way from the dealer for a reason. I imagine just to make it a little more lubricated to press in.