A little bit off topic but I've seen a small freeze plug blow out under pressure in the cooling system.
My sister-in-law had a 1984 Nissan Bluebird. Appalling car - look it up. 4 cylinder 2 litre engine. She called me to say the engine had run out of power driving on the freeway. And it "smelt funny". So I go and fetch her and see the engine has been red hot and the sump is full of soupy white oil.
Towed it home and had to pull the engine. Engine had been replaced a few of years earlier but it was long out of warranty. Cheapo job done. Those engines are a cast iron block, aluminium head, overhead cam, and the entire timing chain/water pump housing is also alloy. In the front of the engine between the block and the timing cover is a 14mm freeze plug. It was OLD. Had not been replaced when whoever had gone through the engine. And it blew out, straight into the timing chain housing, dumped in the water and that was then end of the thing.
Guess who had to go and find a good second hand engine, replace ALL the freeze plugs and get the thing going again.
