RTV Silicone

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Aug 27, 2004 | 05:55 PM

el conquistador

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RTV Silicone

which color is the best to use on a rear diff. cover? what is the difference between colors?

Aug 27, 2004 | 05:58 PM

maticuno

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From: California Desert

I'm sure I probably don't use it "according to manufacturers specifications" but I always use the dark grey stuff for everything. It would probably blend in with the diff. cover if you squeezed some out when torquing, too.

Aug 27, 2004 | 07:40 PM

ammo troop

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I use the blue for everything that doesn't get hot (exhaust for instance)

Aug 27, 2004 | 08:22 PM

Big Jim M

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From: Central Texas

And I would not use any of any color on thet cover! Getcha a gasket and you won't have that mess to clean off next time. Any parts house will have a gasket for it. There are only 2 or 3 places on a complete rebuild that should have any sillycone on them.
Big Jim

Aug 28, 2004 | 04:55 AM

CowboyBilly9Mile

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From: Eastern WA

OEM uses silicon sealant (Ford part # F7AZ-19554-EA) and it looks like Permatex black. I've used it on the rear end cover and it works just fine. For this job, use the Permatex instead of the gasket. When you do find a gasket you may be just as lucky as I was when you install it. I was tightening the bolts on the rear end cover and cracked it (it's plastic) at one of the bolt holes due to the gasket compressing.

Aug 28, 2004 | 05:36 AM

DetailerDave

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From: Phoenix, Az

I replaced an axle bearing last weekend on mine and used the black RTV, as the factory also used black silicon sealant.

Aug 28, 2004 | 07:17 AM

ol yeller

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good stuff

the idea is to not use so much that it gets in the internals of anything. it will eventually break down in oil, antifreeze and grease.

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Aug 29, 2004 | 01:58 AM

ludis

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From looking at the packages, the logic behind the colors seems to be:

Blue: Meant for water/coolant.
Black: For oil.
Red: For exhaust (ie fire).

Aug 29, 2004 | 10:06 PM

#10

el conquistador

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that's cool. i never thought of that. thanks for the FYI.

Aug 30, 2004 | 08:58 AM

#11

G2IC_Wraith

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From: Virginia

Replaced mine on my 88' with a FelPro gasket and a thin film of Permetex black smeared on the gasket. Works great, but I have a steal cover not plastic. Not to much chance of cracking it, plus the tq is only like 15-30 if my brain is working this morning.