Topic:
Freeze plug:
Freeze plugs are mounted on the outer wall of the engine. These are light-metal plates that seal the holes of the internal cooling channels of the engine block. When casting the engine block, internal cores are held in place through these holes and, after production, dust and grinding debris are removed from the cooling channels. An additional advantage is that, when the coolant freezes (when the antifreeze concentration is a bit too low), these plates can freeze and break. This can protect the cooling channels from tearing open, because the pressure of the frozen coolant finds its way out. Because of this benefit, they have been given the name “freeze plug”. However, things can still go wrong, and the block may still crack due to freezing. In that case, the antifreeze concentration of the coolant is far too low, or it is due to an extremely cold climate. See more information here about antifreeze, in other words ethylene glycol.
The disadvantage of a freeze plug is that they can sometimes start to leak. Coolant then runs to the outside, or it mixes with the engine oil. In most cases, they can be easily replaced individually.
