The weekend after this thread was posted I went back down my dad’s and we put the exhaust on the car. Let it run and then changed the oil. Let it run more and burped the coolant. Then I attempted to drive it home. By now it was getting dark. First we (Irene was following me) stopped to get some dry-gas. Then we stopped so I could put some air in the tires. The whole time the temp gauge was off-the-scale cold. I figured it was broken.
Leaving the gas station I noticed some condensation on the windshield. We were going to get some food before driving home. Well a few miles later there is steam pouring out from behind the dash! So we end up at a BK. Got food and waited for the car to cool off. Went back out and filled up the radiator with water from BK and then high-tailed it back to dad’s.
The next day there was coolant all over the driver’s floor! So we start looking for issues and the obvious one is that one of the cooper heater core lines id bent up a little where the hose slips on, which is also where it goes through the firewall and is over the driver’s footwell. So my dad attempts to fix it by banging a socket in it to re-round it out. I took off the t-stat housing b/c I suspected there was no t-stat in it (race motor remember) and I was right. So I get a t-stat and some new hose clamps and we get it all filled up and run it and just when I think everything is OK Irene feels a drip on her leg under the dash!!! 😡 So we start taking the dash apart. All this work was after running an autocross in the morning so we were tired and cranky and decided to quit.
Another week went by before I could get back down to work on the car again. We (my dad & I) took out the dash to get to the heater core. Not a small task in the Miata. What we found when we got everything out was that the leaking still appeared to be coming from the copper tube to rubber hose joint. One of the pipes going to the heater core on the Miata is actually attached with a short hose instead of being an integral part. This is that part that was really messed up. My Dad attempted to further round out the hole but ended up flattening one of the bends. Then I discovered two cracks in the tube where the deforamtions happened and the hose fits over. So I had to find another one of these tubes but at least I didn’t have to get a new heater core.