ok so the t-stat is hallowed out. theres this plug that stops coolant from flowing through the tunnel could someone explain? all it seems to me is it stops coolant from flowing through the tunnel and it just fully goes the other route.

 

When the thermostat closes, it opens a bypass port so that coolant can circulate around the engine to it warm up evenly. When the coolant gets hot enough the thermostat opens to allow coolant to flow through the radiator, and at the same time closes the bypass port.

If the thermostat is gutted (which is a race car mod, not a street car mod) the bypass port has to be blocked to prevent coolant bypassing the radiator.

Unless this is a race car, I'd remove the plug and replace the thermostat with a new one from Mazda.

 

thanks for the info i bought the engine from a race car but its going in the repu!