This is pretty boneheaded of me but...
The rx7 was leaking coolant from somewhere while it was sitting in the driveway. Well I decided to fill it up with water just to see if I could spot the leak, well it wasnt leaking so I left it in there hoping it might while I was gone. Well... needless to say I forgot all about it and then it got cold overnight. Was 80 the day before then all of a sudden the temp is in the teens. Well when I finally got back to the car I noticed the freeze out plug was on the ground and the car had no compression anymore. So I pulled the engine, tore it all apart to find this:

*This picture shows the crack on the surface of the housing.

*This picture shows the piece that broke off inside the water jacket

*This picture give some contrast to the second picture

 

Ouch. Damn weather.

No pictures showing up, just little question marks...

 

There they are.

 

Sorry to laugh but lol ... could have happened to anyone though. We have weather like that here in alabama. one day it will be 70-80, next night its in the 10-20 range, then back to 70 again. pays to keep at least a little antifreeze in the system at all times. though i cant say much as im running straight water right now, but i dont plan to see anything near freezing again till october. sucks to hear though, at least you have an excuse to rebuild?