Soo... apparently I started to have a coolant leak about a week ago. I noticed the low coolant light come on a couple times and I finally tracked it down to the water pump housing where it connects to the front iron. Here's a pic of when I started work on it a few days ago.
You'll see I marked the source of the leak here on the water pump housing with a white circle.
Now when Johnny Tsunami and I finished putting this engine together before we put in the car, we opted to use
Right Stuff liquid gasket in place of a normal gasket.
Until now it held up fine, but I think I know what caused the leak. Mazda uses a pair of copper washers as spacers in between the water pump housing and the front iron to equalize the tension on the gasket. If you don't use a gasket, and use RTV instead, you really should remove these spacers. Otherwise, the water pump housing won't mate totally flush with the front iron and eventually you'll get a leak. Here's a pic with the water pump housing removed, with the spacers I mentioned circled in white.
Now rather then reassemble this again with RTV and take my chances, I opted to cut my own gaskets out of some high quality, blue rubberized FelPro gasket material. You can see the blue gasket material here for the waterpump itself, the housing, and also the water neck/thermostat cover.
I also decided to put on heavy-duty gold-plated battery terminals and some thicker gauge wire for my extra grounding cables.
I use Zerex G05 Antifreeze (which I recommend for an older import car) and distilled water. After burping the coolant system for a while and a test driving it temps are back to normal.
