I recently had an issue with my car randomly overheating I took it to a mechanic and the mechanic came back within less than 20 minutes claiming it was a blown head gasket although my friend his mechanic savvy says that the mechanic is probably lying and just wants to make money off of me. My friend said that he thinks it’s a bad freeze plug and that changing the freeze plug may stop the issue however I can’t seem to find any information on any websites or online forums please help thank you Scotty!
Here's a discussion of freeze plugs on Miatas (one of several on this miata.net forum)
https://forum.miata.net/vb/showthread.php?t=213810
A bad freeze plug is not going to make the engine overheat unless it leaks a heck of a lot of coolant out.
Freeze plugs in the block rarely fail these days. If there is coolant in the oil, you have a blown head gasket. Running hot could be something as simple as a bad radiator cap or bad thermostat.
