So, this is down in my center iron, a BIG crack where the coolant pushed up into the oil area. Would the only possible cause be freezing? I can't think of anything else, but maybe I'm missing something.





I bought this car from a guy who parked it around 5 years ago when he had a water seal let go. It's hard to tell if the water seal was the problem or if this was the cause of it all.

 

Oh damn.. That looks nasty.. RX-7 Gurus.. get on this stat!

 

Looks rusted to me. Maybe the guy had only water in the system and let it sit like that for 5 years. Then, when freezing temps came it expanded and broke, then started to rust. I'm no expert, just a thought.

 

I'm pretty sure that it froze, I can't see anything else doing that

 

probably overheated and got so hot it cracked, thermally expand and then when cooled cracked prob.

 

Most likely the block froze. The freeze plugs do not protect the block from cracking. I have seen several irons with 3x3 holes in the smooth face where the metal cracked and pushed out. I once had to forcibly start (tow) a car I bought only to find that it drank 4 quarts of oil and most of the coolant in less than a mile (not to mention the smoke). Upon teardown it had a big chunk of an iron face missing.

An overheat shouldnt cause that, though it is possible. There are far thinner and more suceptible castings that an overheat will crack.