Question about RTV

[rbattelle]

I'm getting ready to change transmission fluid and axle fluids (along with Mag Hytek and fastcooler install). Both procedures require the use of RTV.



Do I need to let the truck sit for a certain time to let the RTV cure, or is it ok to apply, assemble, fill, and drive away?

 

[Whitmore]

Prefered to let sit before adding the oil but it wont hurt to add oil and go.



Cheers, Kevin

 

[MarStock56]

RTV QUESTION

I always let the RTV "skin over" before I reassemble the parts. That usually is all the time you need to get all of your new fluids ready to add... once reassemled, the fluid can be added and the truck driven away.

 

[RobbieH]

I believe you have it backward. Don't let the RTV skin over, instead install it right away. Proper procedure is to let it sit for a while before installing the fluid, but I've done several without waiting with no issues.



Since this image is big, I won't post the image directly, but here's a page from the Dana service manual that describes it. Yes, I know this is not a Dana axle, but the procedure is the same.



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[rbattelle]

I have heard before and used the method of letting the RTV skin over before assembly. It's also what is suggested in the Fastcoolers instructions. I guess I'll let it skin over, then assemble, then give it about an hour before filling and driving away.

 

[Badunit]

Ive seen the debate about skinning over vs not skinning over but haven't seen a definitive answer either way. However, I'm in the not skinning over crowd for several reasons:



1. The RTV tube says to assemble quickly (i. e. , before it skins over).



2. The service manual says to assemble quickly.



3. It would seem that if it skinned over it would not adhere as well to the mating part and would make a weaker seal.



I haven't heard any counterpoints for the other side of this debate. I'd especially like to hear a counterpoint to #3 if there is one.

 

[Vaughn MacKenzie]

I think if you pop it on right away it lets the RTV slime onto the opposing part and stick better, creating a good seal



Maybe the skinning idea is to allow acceptable sealing performance yet make it easier to remove the part later on by it peeling off the "skinned" side easier.



Who knows. . .



Vaughn

 

[curatchko]

Transmission does not take RTV. It's a reusable steel lined, rubber gasket that goes on dry.



Was on my 47re anyhow.



Chris

 

[Fireman]

rbattelle,



Verlin Fast recomends using rtv on his coolers, but you shouldn't need any for the diff covers. The Mag-Hytec cover has an o-ring and if you have a 4wd the front diff has a reusable gasket and no rtv is required.



Even though the Mag- Hytec cover has an o-ring and requires no rtv, someone on this board once recomended filling the bottom bolt hole on the rear diff. with rtv to prevent leaking. ( The M-H cover doesn't use that bolt hole)



Fireman

 

[Coalsmoke]

I think that letting it skin over is just a way to make sure that all the RTV doesn't get squeezed out. When we reassemble, we RTV, make instant contact and half-tighten the bolts so that the RTV has moved but not squished everywhere. Then we let sit for 30 minutes, and then do final torques and it works great for us.

 

[Prairie Dog]

You won't need RTV for the differentials, they have a reusable rubber seal.

 

[Spyke]

I have used both methods but here is a little tidbit Room Temperature Vulcanizing or RTV.