I've owned three RX7s, all of which lost coolant. The 81 GSL always smoked a little on startup but never got bad enough to fix. The 86 GXL eventually crapped out completely and required a rebuild. The 88 Turbo II was on that road until I made this fairly interesting discovery. In the interest of avoiding a teardown, I formulated the following gameplan to see if I could prolong the life of the turbo's o-rings:

Most people try to address leaky o-rings by adding stuff to the coolant, but due to thermal expansion and the modular nature of the rotary engine, these methods are temporary at best. That being said, I put Block-Seal in the coolant to stop the immediate leak. I ran the motor up to operating temperature per the directions, but I neglected to remove the thermostat, which the Block-Seal GLUED SHUT. The motor overheated and blew the heater hose right off. Nevertheless, the motor was sealed sufficiently to drive for a few days, so I drained & refilled the coolant. At this point I added STP Engine Oil Stop Leak to the oil and added coolant periodically until eventually the level was constant. The long and short of it is that the oil stop-leak dressed the o-rings from the combustion chamber side. I know that STP stuff works because when I had the car in to change the oil, the filter gasket was swelled to the point where they couldn't get the filter off.
I put 60,000 miles on that motor AFTER I declared it DOA, and when I sold it, it was tight as a drum.

I'm so convinced this works that I'm considering a side business buying smokers dirt cheap, sealing 'em & putting 'em back on the road where they belong.

Just thought this might be helpful.

 

Crap.. wish I had known about this when I had my 91 smokescreen. Had to end up selling it to carmax (drove it up there nice and hot, so no smoke..) Lost a ton if cash on that deal. Grrr.