Non-H2 stupid technical question

[CO Hummer]

I'm going to change the diff fluids on my '99 Burb tomorrow. The rear diff requires a gasket (which I have).

My question is - Do I need any type of sealant when I use a gasket? Just rub a little fluid on the gasket to moisten it up?

[Big Z]

Just on the cover side!...No-permanent Goops...Like the spray when I did My own!

[CO Hummer]

Originally Posted by Big Z

Just on the cover side!...No-permanent Goops...Like the spray when I did My own!

Just WHAT on the cover side? What non-perm sealant/goop should I use?

[ssgharkness020147]

When I work with gaskets I like to use Permatex Anerobic gasket maker. You dont need to cover the whole gasket, I run a streak between each hole, then let it "set up" for 20 or 30 minutes before you install it.

On another note. I dont know what type of diffs are in your Burb, but MAKE SURE that you do not need a friction modifer! If you do make sure to add it, you'll can really shorten the life of the diffs without it.

[ssgharkness020147]

Put the gasket on the diff cover, not the diff itself.

Originally Posted by CO Hummer

Just WHAT on the cover side? What non-perm sealant/goop should I use?

[Big Z]

[CO Hummer]

Originally Posted by ssgharkness020147

When I work with gaskets I like to use Permatex Anerobic gasket maker. You dont need to cover the whole gasket, I run a streak between each hole, then let it "set up" for 20 or 30 minutes before you install it.

On another note. I dont know what type of diffs are in your Burb, but MAKE SURE that you do not need a friction modifer! If you do make sure to add it, you'll can really shorten the life of the diffs without it.

Thanks for the info.

Oh, and I had already checked - no friction modifier should be put in for GM 10-bolt/8.5 diff.

[mdoyle]

I use a very light coat of Permatex Blue on the cover, then align the gasket and apply a small weight, keep it on a flat surface (your glass coffee table will work provided your Wife doesn't catch you putting car parts on it). The kitchen counter is another good spot, you just want a good flat surface to establish the gasket bond in a coplanar fashion.

Let it set up about 30 minutes, then install making sure the machined differential casting is completely clean and free of old gasket material. You don't want to see any Permatex squeeze out between the gasket and cover, if there is you've installed too much, clean it off to avoid contamination of the differential.

Do not apply lubricant to the gasket, that's common practice on oil filters to compensate for sliding friction as they are tightened, and prevents seal distortion, but it doesn't apply to this style of seal.

Torque the cover bolts in a crossing pattern, I'm guessing to around 14 to 18 lb ft, but verify that with a reliable source.

[tomp]

Actually it is a good idea to use friction modifiers in all type diffs as it helps the fluid run cooler. This information comes from redline. It does not harm, in any way, diffs that do not require it such as the H2 .

[CO Hummer]

Originally Posted by tomp

Actually it is a good idea to use friction modifiers in all type diffs as it helps the fluid run cooler. This information comes from redline. It does not harm, in any way, diffs that do not require it such as the H2 .

GMs literature (as well as infrom automotiveforums.com) specifically say in Capital letter to NOT use friction modifier in these axles. I know there's debate over it.

[tomp]

Is that for the Burb or H2? Also, does it have limited slip, locking diff or open (like the H2 has)?

[Dug]

co hummer - just use the gasket by itself and you will be fine. If you want to use one of the many gasket "sealers" along with the gasket you can but dont need too. I wouldnt use gasket "maker" with your paper gasket. Tighten the studs in a cross pattern and torque to specs if you really want to be perfect. doug

[KenP]

Gorilla Glue.