My engine has a coolant leak, but instead of coolant leaking into the rotor, combustion leaks into the coolant adding massive pressure to the coolant system. My question is would that problem fix with a rebuild or would I need some new rotor housings...or core. 1986 nt rx7.

 

Rebuild, likely with a new iron, possibly a rotor housing depending on warpage. Typically happens due to an overheated engine cracking the coolant seal groove on the iron. Might have lucked out and just toasted the coolant seals, though.

 

The same thing happened to my NA. When I pulled the motor apart the intermediary housing was toast but the housings were still in good condition.

 

Same. My middle iron was foobar and had 1.5 inches of the coolant seal groove missing. Blew it during an AutoX, but still put another 15k on it before it just became to difficult to start and too expensive to replace coolant.