Review on Stant-48728 Stainless Steel Engine Coolant Thermostat/Water Outlet Assembly: Enhanced Performance and Durability by Eric Rose

This thermostat does not appear to have an air vent like the other thermostats sold here and at Autozone (with plastic pins holding the element in place). BTW the second photo on this Revain listing (showing the dimensions of the thermostat) is of a linked thermostat which is a different model. You see what can be seen in the first picture. When my mechanic replaced this thermostat in a 2006 Mazda3 2.3L, the car started overheating like crazy and the thermostat hose was soft (no fluid) and cold. The heater core was working fine, but its hose (from the second outlet of this thermostat) was hot. I did the "bleed" procedure (2.5k rpm + 3.5k rpm) as recommended by Mazda. But without success. It took a few days (thankfully it was very cold) for the problem to go away on its own. The hose became hard and hot. So I attribute this problem to the lack of a vent in this thermostat. Other than that, this is a great device. My temps are now 82-90°C (use an OBD reader to see the actual coolant temp, the temp gauge on the Mazda dash is useless! It stays in the middle whether you're at 72°C or 98° C or somewhere in between).