Leaking differentials

I have put new gaskets in both my differentials (front and back) and they both leak (a little). I used an ample (2/3 of a tube) amount of RV (for gaskets) from NAPA on each. All the bolts are tight... what am I doing wrong?

 

Most likely, your covers are "dimpled" around the bolt holes from people over tightening them.
Make sure the gasket surfaces are flat!

 

What he said
Also make sure surfaces are absolutely clean and oil free or the sealer will not do it's job. Some diffs also have cover bolts that go all the way through and oil can leak out the bolt holes. 2/3 if a tube is a lot. All you need is about 1/8" bead around the cover surface.


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I used the permatex RTV sealant for gear oil on mine and it worked great. You can get it at your local parts store but here is what you are looking for. http://www.ebay.com/itm/Permatex-RT...se-Differential-Gear-Oil-3-0-oz-/130712068314. Also follow the other recommendations previously listed. And let it set up before you fill with oil.

 

I just recently started following the instructions on the back of the permatex tubes. Never read them before, honestly. Squirt it on and tighten it up, right? That's what I thought. I was wrong. According to the instructions, after applying your bead of sealer, tighten the bolts until the sealer begins to squeeze out from between the surfaces to be sealer. Then, wait an hour, allowing the sealer to cure a little. Then, finish tightening down the bolts. Allow to cure for 24 hours before filling with oil.

I know most folks, and many shops, won't wait around for the stuff to cure. Sometimes you get away with it, sometimes you don't, I guess. I've had better success since I started following their instructions and being a bit more patient.

It's also important to remember that all those gears and bearings have oil all over them. That stuff drips for a long time if it's not all removed. It drips off those parts and puddles at the lowest part of the housing which is right at the bottom of the cover you are trying to seal. I believe this interferes with the ability for sealer to do it's job.

 

Good info guys thanks. I am going to redo them... really clean and dry them well... inspect the cover for warping... and try the mentioned permatex RTV.

 

Make sure it's not the pinion seal leaking- bad seal, worn out yoke- that sort of thing. It can look like the cover plate gasket is leaking when it's the pinion seal leaking and the 90w gathers at the low point of the diff.