Thermostat
 

2000 xj. Just replaced thermostat. How long should I let it set before driving so I dont get any leak's from the housing?

53 minutes should do the trick.

let it set?

i've never let it set, always just used the paper gasket.

Did you use rtv? Shouldn't have to wait too long.. maybe 20 min. I'd recommend just getting a gasket.. They are very cheap, and don't require rtv.

I let mine set overnight. I hate redoing leaks.

The key to a good seal is how clean/smooth the 2 mounting surfaces are. A thin film of RTV on both sides of the gasket has always worked for me......just fill with coolant after snugging the bolts.

I usually use both rtv and gasket...a thin film of rtv to 'glue' the gasket in place, snug the bolts and fill, as previous post said

If your concerned about it leaking use Permatex Indian shellac, that stuff could have saved the Titanic.

That and GasgaCinch are 2 of my favorites.

What does it actually do to the gasket? Make it swell or just stickier?

Both are just good old-fashioned gasket sealers. Used for a gazillion years before rTV and with excellent success.

Indian shellac is great. I use it on any kind of intake gaskets. It will seal with no air leaks. Coat both sides and let it tack up, then install.

This may sound a little weird, but on all my gaskets (except exhaust) and o-rings (that don't involve glycol) I use a silicon grease. Rarely ever have a leak and it always comes apart clean later down the road.