Fel-Pro rear differential cover gasket

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I want to install a Fel-Pro rear differential cover gasket on my wife's Expedition. The Expy does not have, & did not come from the factory with a traditional gasket. It came with an RTV-type sealer, & that's also what the shop used the last time I had the fluid changed.

When I install the new Fel-Pro gasket, am I supposed to use any type of RTV or other type of sealer in conjunction with the gasket? The package doesn't specify one way or the other, & my repair manual only gives instructions for using RTV-type stuff to create a "gasket".

Thanks in advance.
 
No, RTV is not necessary when using the Fel-Pro gasket. I used a Fel-Pro gasket both times I serviced my differential, and never used the RTV, no leaks at all. My auto tech teacher in high school said that the gasket is plenty sufficient.
 
C.T.,

Thanks for the info. It's always good to hear from someone who has first hand experience.
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Thanks for all the suggestions, gentlemen. I appreciate your thoughts.

fwiw, I just checked the Felpro website, & they don't recommend using RTV in conjunction with their differential cover gaskets.
 
I just used a fel pro gaket onmy rear diff. I used a few dabs of RTV to hold the gasket in place. I am almost positive that the directions said to do this, but it is not neccessary.
 
quote:

Originally posted by cousincletus:
If the truck came from the factory w/RTV then it's best to use it instead of a gasket. The pan is a little different.

I'm going to go ahead & use the gasket, & if it leaks, I'll start over & use RTV. My bigger concern now is that I think I have a bad right side axle shaft.
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The main thing you'll really want to do, since you're using a gasket, is do a thorough job of cleaning the mating areas. I use a putty-knife or flat screwdriver, scrape it good till smooth, then take some sandpaper and do a light sanding so I won't get any flakes in the gears. The gasket should mold into any slight imperfections (not warped flanges or gaping holes in the mating area) when torque fully.
 
Use a torque wrench.
All the prep in the world is meaningless if it is squeezed too tight or left loose.
 
Get everything super clean, then use a light coat of RTV on both sides of the gasket. Let it dry well before refilling.
You won't have to do it twice.
 
quote:

Originally posted by Steve S:
wavinwayne ,what is the gasket made from ? paper cork or rubber type?

It's not metal, & it's not the traditional cork type. It's almost black in color & seems to be made from something resembling paper, but with a "plastic" feel to it; it's hard to describe.

If you go to partsamerica.com, & search for a '97 Expedition 4.6L 8.8" rear diff. cover gasket, they have a good picture of it there.
 
RTV DOES NOT BELONG ON A GASKET.

WW, get yourself a tube of Permatex 2B. It's a very dark brown sticky cream that remains pliable. It's purpose is to preserve gaskets by preventing the degraduation of the gasket material by oil or water; hense the name sealant. It's not intended to be used on gaskets exposed to fuel.

This is what I do: I lay the gasket down on a news paper. Then I coat one side of the gasket with my finger. Then I apply the gasket to the cover.. While the gasket is stuck to the cover, I then go and coat the other side of the gasket.

You don't have to worry about the stuff drying real fast like adhesive, because it never dries. I also should mention that the only way to remove the stuff from your hands is with brake fluid.
Permatex 2B is only for cork or fiber gaskets, it's not to be used on rubber.

GR
 
Permatex makes a brown gasket cement that works well. You put a few dabs around the gasket and it holds it in place while you install the bolts.
 
That is a coated fiber gasket that's used on lots of different applications.

Everybody has their own method - mine is that I spread a VERY thin tack film of rtv on the gasket before installation. I like the rtv because it cleans up easier the next time I remove the gasket and it seems to fill any small imperfections in the mating surfaces. This the method I have used and prefer for many years. As with any sealant, do not glob!

You can also use the Permatex #2 - it's good stuff.

You can also NOT use anything as mentioned above.

It's up to you.
 
If you use the gasket I would recommend using the RTV. I put mine on without RTV and it started to leak within a few days. My mechanic told me to use black silicone and that worked perfectly.
 
Well, thanks again for all the added responses. I'm going to trust Felpro for now, since they say there is no need for a RTV, sealer, adhesive, etc.

I'm just going to clean the mating surfaces, & slap the new gasket on & go. If it leaks, I'll consider it a lesson learned, & an additional excuse for me to play in the garage.
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I like to read Ford threads, just because of the shop memories. Unfortunately after one tech quit I became the default "rear end guy" (don't start), so I ended up doing about 20 diff rebuilds/year.

I never had a leak just using a 1/8" black RTV bead on the cover and zipping it down with my 3/8 impact. I never saw a diff cover from the factory leak either. Just curious why some of ya'll are going to the trouble to put a gasket back there when it wasn't designed for one.
 
quote:

Originally posted by punisher:
....Just curious why some of ya'll are going to the trouble to put a gasket back there when it wasn't designed for one.

Because I am cursed with a desire to improve things that work fine, & to try to fix that which is not broken. It's a hard life, I tell ya.......
 
You may have a little seepage around the pan w/paper gasket. If you pull a trailer and change @ 15K intervals I can see where you may want to use a paper gasket, but you will be defeating the purpose if you use any kind of permatex with it. It's just quicker and easier to change the oil w/paper gasket.
 
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