vauxhall thermostat housings Available Here. Thermostat housings are located at an important intersection in your coolant system's hose network. Coolant cycles through your engine until it reaches a certain temperature. Then, it’s routed off to cool down in your radiator. Temperature is measured by coolant thermostats, which are contained in thermostat housings. Since these parts are routinely subjected to high pressures and temperatures, they often develop cracks or other faults that compromise the entire coolant network. You might see anything from an overheating engine to coolant leaks when one of these parts goes bad. Replacing faulty thermostat housings, coolant hoses and gaskets at the same time is a good idea, especially if all of the parts are around the same age.