I have replaced my rear differential gasket twice the one that goes behind the differential cover. Its still leaking any ideas on why its still leaking after replacing the gasket twice
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Is the diff cover warped? You may want to replace it if it is. They're usually not expensive.
Did you try to snug up the bolts some more?
What kind of gasket are your using? cork? rubber? paper?
Did you thoroughly clean the mating surfaces? What kind of gasket did you use? (I like to use Lubelocker differential gaskets on diff covers if available for the application.)
The fill plug is located on the passenger side of the differential snout. Post #16 in the 2nd picture shows the location.
https://www.tahoeyukonforum.com/threads/what-to-upgrade-at-160k.63397/page-2
use a flat head on the top to open it up a little to put the gear oil in. Maybe it could've bent the cover?
yes you did. That's not how you do it.
Autozone gave me a paper gasket.
use rubber
There is a fill plug, you just haven't found it yet. It's either on the differential housing or the differential cover.
My rear end doesn't have a fill plug or a drain plug so I had to put a few bolts at the bottom and use a flat head on the top to open it up a little to put the gear oil in. Maybe it could've bent the cover?
Unfortunately you may well have distorted the differential cover. When you pull it off to reseal it, check with a straightedge to see if the gasket surface is flat. Or maybe just buy a new one since they are not all that expensive. Check out this video on rear differential service on '99 Tahoe, it shows the fill plug on the housing on the passenger side:
https://www.youtube.com/watch?v=smfWJt5eW5U&t=843s
https://www.carparts.com/differential-cover/chevrolet/tahoe/1999
https://www.amazon.com/Differential-Chevrolet-Silverado-1999-2008-Suburban/dp/B07DVD4Z9W
Usually, the cheap, cork gaskets are the worst. Get a high quality piece, like FelPro, use an appropriate gasket sealant and tighten the bolts incrementally in a criss- cross pattern to specified torque.
Thank you for the reply and ideas. Autozone gave me a paper gasket. One of my buddies told me to try a metal gasket. I cleaned it made sure there wasn't any left over from the old gasket and rtv that I used I tried to tighten the bolts up more but would tighten up anymore I don't want to do it too much. I don't want to end up snapping one if the bolts . I have a 99 chevy tahoe 4 wheel drive 5.7 the first gasket I used it was leaking but wasn't leaking as bad once I put the second one on it started to leak more then the first one. My rear end doesn't have a fill plug or a drain plug so I had to put a few bolts at the bottom and use a flat head on the top to open it up a little to put the gear oil in. Maybe it could've bent the cover? Or tore the gasket? But it wouldn't have anything to do with the bottom of it since it's leaking at the bottom would it?