Project: 1995 Miata

[Jake]

so it sounds like the cooling system isn't the problem, but maybe a symptom...good rad, good coolant, thermostats fail open, and you're making stock power. i wonder if it isn't something weird like a clogged cat. did you notice any weird smells (like metal cooking) or any really intense heat coming up from the floorboard? when you first ran the car after the swap, was it running over-rich or anything like that?

if the cat was clogged up it would certainly prevent you from making power (either through the physical breathing problem or the ECU retarding timing like whoa) while also keeping the engine from evacuating a lot of hot spent gases - i wonder if that in turn would cause a heat soak of the entire engine, ultimately leading to the cooling system struggling to keep up.

new water pump went in with the swap, yes? metal impeller or plastic? if you lost an impeller fin i wonder if that would hinder circulation.

The car has stunk here and there. Keep in mind, the old motor was shooting oil through the exhaust so the cat is likely saturated. It still spits some residual oil out the back from time to time. I wonder if a new cat + catback is part of the answer, just for piece of mind.

Yes, new water pump went in with the swap. I think they are metal impellers, it's just a stock Mazda WP but they are fairly hardy.