The Stovebolt Site Forums The Shop Area Engine Shop 216 Water Pump, T-Stat, and Other Cooling system Questions

It’s been a while for me but usually I would run the engine with the cap off until no bubbles are seen and the coolant should be flowing when you look down the rad cap hole ,I don’t know if drilling a hole in the thermostat would prevent a airlock once the cap was put on . But if you may be correct airlock does not occur to often .