Leak then no leak. Sorcery!
 

Just replaced my stuck open tstat. While I was in there I replaced the water neck. Well it was leaking... And leaking bad even with the truck not running. I looked and saw it spraying out on the front edge of the water neck. I kept adding coolant like you're supposed to do. Well sure enough that leak isn't leaking anymore. But I can't help but be worried. I did use black gasket maker just to get the fel pro gasket to stick on the next as I put it on place. Thoughts?

If you don't trust it, just re-do the gasket. Easy peasy. Or you can get in the habit of popping the hood every time you stop the truck to check it.

Well it seems to leak till it warms up. Guess I'll be digging back in there again. I only took the alternator out, so access was limited but doable. What's the best method with the gasket maker? Both sides of the gasket? Can I reuse this gasket or is it trash?

Make sure the thermostat housing bolts are not to long, as they can bottom out and cause a leak that you cannot easily detect.

Both sides of the gaskets, use a new one.

I don't remember what I did but I think it was both sides so it stuck when attaching the neck to the manifold. I don't wait to let it set up anymore; just attach it. I let RTV set the proper time once on my rear end and it leaked right away.

i usually wait overnight for rtv to set before i add water. depending on the rtv it can dry, and be ready, as fast as an hour but i still wait overnight.

Sorry, meant the initial set up once it's squeezed out. Think it says 15 mins or something to get tacky. I don't remember. Once I apply it, then I attach whatever part I need to immediately without timing it. THEN I'll wait for it to dry a while before oil or water is added.

Can I just take the upper rad hose off? Rather than drain all this new coolant out? Also, what rtv to you recommend using? I only have the black stuff. But it looks like the previous gasket was installed with a blue rtv. Also, what is you guys easiest method at getting to the tstat? I just unbolted the alt and went in that way. I also grinded off that metal lip on the water neck. What's the benefit of drilling a small hole in your tstat like someone said above.

Some t-stats have a bypass made into them. Drilling a hole creates a bypass which basically helps only when you are filling the system and helps with burping the air out of the system. I noticed in one post you say the RTV squeezes out. If that is the case you are using way to much RTV. All you need is a very thin film of RTV and that is just to hold the gasket in place while you are installing it. Make absolutely sure you replace and washers and lock washers and it is wise to replace the bolts and make sure they are a grade 8 bolt. Bolts can stretch over time. Now for the picky part. Use a strong light and make sure the surfaces are absolutely clean. I used to use a razor blade and sandpaper to clean the surfaces. I assume the t-stat housing is the steel type and not the cast aluminum housing? Just be super careful when tightening the housing down to do it as evenly as possible. Those steel housings can be warped very easily.