did you use an oem or aftermarket one?

 

The cover was an aftermarket from Summit. It is a Dorman (plastic?) cover and was the only one I could find that said it would fit my 07 Sierra Classic. I'm also wondering if a steel or aluminum cover from a different year would also fit?

 

I went through 2 aftermarket covers then got one from Chevy and the leaks stopped . . .

 

Thanks for the reply. I'm thinking that an OEM cover from a GMC dealer will be the way I go.

 

BUT, when I installed the timing chain cover from Chevy, I also got their pan gasket and installed both. Haven't had a problem in months now . . .

 

is it leaking where the pan gasket meets the cover gasket? what we do is put black silicone there and never had a leak. lots ls swapped stuff that was done somewhere else comes in for a leaking cover gasket and it turns out to be just that. most shops will tell you its a cover though..

 

both aftermarkets covers I purchased just didn't fit right. I used black silicone rubber where the pan gasket meets the cover gasket and it still leaked. I even let it dry overnight! One even leaked from the crank sensor hole even after I put new "O" ring. Frustration set in so I spent the bucks and purchased GM and now it's fine.

 

It's kinda funny: Sometimes you actually have to spend the money and go OEM instead of cheap Chinese parts if you want to fix the problem.
Of course, there are times where OEM is just too expensive, for no good reason, or the aftermarket has fixed a deficiency in the OEM part.
The worst part is that you almost never know which case is which until you've swapped the parts a few times.