Rtv sealant, get a new gasket then cover all mating surfaces of the thermostat housing, and the inlet pipe with rtv sealant. Keep in mind that the sealant will squirt out when you the tighten the bolts so don't put too much on there, just enough that a thin bead of sealant is visible all the way around the thermostat after the bolts have been torqued. Make sure to follow the directions on the package and allow the sealant to cure before you add fluid to the cooling system!
thermostat gasket probably leaking. replace thermostat and gasket making sure that thermostat housing is flat.
The housing gasket may be bad. Replace the gasket.
remove old thermostat and replace with new thermostat and gasket
Replace the thermostat housing seal or gasket.
only if the gasket under thermostat is leaking and may-be it's the hose clamp on the hose that is leaking
valve cover gasket
You should use a thermostat gasket along with the thermostat housing ring. The gasket should be replaced every time the thermostat housing is opened.
Remove the housing and replace the gasket.
can the gasket go bad behind the water pump houseing
No just make sure that the engine is cool. take the radiator cap off MAKE SURE ENGINE IS COOL... then you can take the thermostat housing off and replace the gasket you might have to replace the thermostat as the gasket might be an O ring around the Thermostat and not bought separatly. after your done fill up with water.
In general, engine thermostats can be found by following the LOWER radiator hose to where it attaches to the engine. The hose is typically attached to a fitting behind which is a gasket and the thermostat. The gasket needs to be replaced when the thermostat is replaced.
YES