[MacGyver]

I have fought that battle before only to discover the leak was around the bolt threads. This can happen on t-stat housings as well as front cover and water pump bolts. Be very carefull and check front cover and water pump bolt threads as they can be a bottom casting for the bolt hole causing a hydrolock of sorts breaking the casting when bolts are coated in areas when the hole bottoms out instead of penetrating a hollow. A friend of mine recently broke a chunk of his block off using too much sealer in an area where it wasn't needed. i recommend probing the casting with a pick first. If the hole bottoms out you shouldn't need sealer. If it penetrates into into a water jacket you should definatily seal the threads. A thin coat on all bolts should ensure a good seal regardless.