I have replaced the thermostat housing gasket 4 times and the damn thing still leaks! Its not a bad leak but still it just pisses me off. I called around to see if i could just buy another thermostat housing but, I have the unique gonzo nose looking one that only the dealership carrys. And im not paying $93 for a new one. This last time I replaced it when I was cleaning out my lower intake manifold. I did it buy the book. I took a fine bristled wire wheel and polished all the gasket surfaces. I applied sealant to both sides gaket. Perfectly aligned the gasket with the housing and torqed both bolts. WTF? Am I not suppose to use sealant?
Might be warped. Take it off an dlay it on something flat. You'll know right away if it's warped or not. If it is, and it's stamped steel like mine was, just take a hammer and punch and pound it back into shape. Just take care not to pound through it.