Upon returning from my monthly exersize of my '88 RX7 (stock 13B, block replaced about 40K miles ago due to blown oil seals) I noticed steam coming from the bottom rear of the engine. It was still full of coolant, though. Later I noticed some anti-freeze leaking out near the back of the engine. I drove it two more times with no problems, but did not get it very hot, so no more steam. The leak continued, and the next time the car wouldn't start. THEN my foggy brain remembered the sub-zero starting fluid tank, which was dry as a bone. I filled it, and thought maybe I could "prime the pump" by cranking the car by towing it down the road, but it would not start. I've been told it might be that the water jacket is shot, but if that was the case wouldn't the radiator fluid leak out? If the starting fluid valve is bad, I can probably replace that, but I'm toast if it's the water jacket.
Any guesses as to which it likely is?

 

Sub zero assist system can be removed. It is not the issue. Check the heater hoses for leaks and pressure test the cooling system by borrowing the tester from auto zone. Pressurize system to 15 lbs I believe and check that the pressure holds for a couple hours . If internal leak then time for rebuild.

 

By "rebuild" you mean replacing the block again?

 

+1 pressure testing the system.

The only other thing I could think to check are the freeze plugs in the rear iron. Someone correct me if I am wrong.

 

OK. I've been searching threads all over and have looked at many coolant leak problems. Suggested explorations are most always in the heater line or other parts of the normal cooling system, and freeze plug (drat on that one!) leaks. What I don't understand is this - if the sub-zero system is unnecessary, why did the FC3C run fine up until all the starting fluid leaked out? But the fact remains that it won't crank now, so it may be just coincidental. But I never observed any steam out the exhaust, or radiator fluid loss, which should (I think) point to a bad water jacket. In any event, I'll check all connections under a pressure test and see what I can see. Thanks for the input and wish me luck.

 

When I do a pressure test, obviouusly I'll see fluid leaking if it's a hose or other external leak. If it's internal, how do I tell? By a drop in the radiator fluid? If it's internal, any way to tell whether it's freeze plugs or water jacket?

 

Freeze plugs leak to the outside.the "coolant" expands and pops them and the coolant leaks out.That is supposed to save the engine.If it is anything to do with a water jacket,then it can leak internally.You will notice lower coolant level amongst other things.
By the way,What do you mean by it doesn't Crank?
Cranking and rolling over is engine movement by the starter.Firing,starting is actual Ignition or Running of the Engine.

 

Thanks for the info, Mr. Styx. Hopefully I'll get a good idea of where tre problem is. Sorry for the nomenclature snafu. Here in NC, "crank" means it fires up and runs. If nothing happens when you turn the key, "It don't turn over."

 

Well, I'm not much smarter than before. I ran a pressure test 6-8 times. Pressure would drop quickly, 15 to zero within a couple of minutes. Radiator fluid never dropped and no leaks. Then I checked at the fluid fill cap and was low, so I filled it to the brim. Now pressure dropped more slowly at first, and sure enough fluid was leaking out (I couldn't tell from where) and dripping under the oil pan. Very small amount, maybe 1/2 an oz till the pressure was gone again. Did this a couple times with same results. Does this sound like freeze plugs?