What do you mean by "guard against a blown head gasket"? Is it possible to stop a head gasket leak by pulling the thermostat?That is where mine is running, and the wife is complaining of no heat. Car has about 100k on the odo. I do wonder if someone pulled the thermostat to guard against a blown headgasket, but I have not checked.
I only ask because i have not looked yet and i was afraid that if i found no thermostat putting one in could cause the head gasket to start leaking.Pulling a Tstat wil not lower the possibility of blowing the gasket. It's important to keep the Tstat in to maintain an "operating window" (temp) for the ECU.