Posts Tagged: thermostat jiggle pin

What a Thermostat Jiggle Pin Does

Understanding the Purpose of a Thermostat Jiggle Pin A jiggle pin works when the engine is off to prevent air pockets from surrounding the thermostat’s wax pellet. When you shut off the engine, and there’s no longer any water pressure pushing against the thermostat, the weighted pin falls, providing a pathway for any trapped air to vent through the hole. So thermostat jiggle pin is a bleeder valve of sorts. How does air get into the cooling system? Any time you flush or drain your coolant you can get air … Read More