So lately I've been having trouble getting the waterneck to seal. Doesn't leak bad, but it's the principal of it. If I can rebuild my own transmission, I should be able the seal the waterneck! Nothing that I can think of changed, it just seems to not wanna seal. Sanding, cleaning, scraping scuffing, nothing worked better or worse. Each time I had to open it up, it took 2 or 3 more changes before it'd seal properly. When I mentioned gaskets, someone suggested I use RTV instead. Some had mentioned RTV AND a gasket.

....I suppose there's no right answer, I'm just looking for some thoughts and ideas on what YOU guys are doing.

 

Sometimes those pieces get a little warped. If you take it off, turn it over and run a wide file lightly across the sealing surface you can find the unevenness. Using a fairly fine cut file, even the surface from multiple angles until flat .Then smooth on a flat surface with sandpaper. Felpro makes a great sealing gasket that is blue and about 1/16" thick with a sealing ring also. Shouldn't need any sealer then. This is assuming you have the original aluminum piece

 

Get a can of permitex Right stuff and done with it. works perfectly on my camaro and s-10

 

I found a combination of RTV and gasket provides the best results. The better quality Felpro gaskets give superior results too.
When installing an aftermarket diff cover not too long ago, the enclosed instructions suggested that after laying on a thin even coat of RTV, the bolts are torqued only to hand tight. Once the RTV has set up, the final torque is applied.
After a couple of attempts at NOT following those directions with poor results, I tried the suggested method. Zero leak.

 

i always used both, never hurt. allows for a little better sealing on parts that are uneven or have poor castings to them

 

hightemp red + gasket = wont leak!

btw, i have a TPI waterneck that sealed just fine on my formula if ya need it..

pay shipping and ill fire it off to ya.