Over the winter I did a desmog and I used 14mm freeze plugs on the top side of the motor.
Last week sometime I blew out a 14mm freeze plug from the right front and today I blew out the left rear plug.

Both times I was accelerating hard when they blew out, and both times the motor was fairly hot. I will admit that I drove the plugs down so that they would be just below the casting on the block. They could have been driven down further but I thought that that would just be a place for water to collect.
My solution to this was to insert a button head allen screw (5/16ths) into the hole and use an allen wrench to allow the screw to thread itself into the casting and then fill the rest of the hole with JB Weld.
Presto!!! A permanent fix, that's cheap and no hassles with trying to locate those pesky freeze plugs.
