How can a freeze plug leak?
Freeze plugs or more properly core plugs normally leak because of corrosion. The metal surface on the back of the freeze plug is exposed to the coolant. Coolant or antifreeze contains corrosion protection. If the coolant is allowed to become depleted corrosion can quickly eat through the freeze plugs from the inside out. When one plug is leaking, the others are normally not far behind. Replacing all plugs can involve removing the engine and/or transmission in many cases. See our Detailed Topic Dexcool, coolant and proper service for even more information.
