Blueprint Engines 383 - My Bad Experience

[AusTx68]

Originally Posted by 68gmsee

Regardless, I'm still confused as to why the engine would run cool sometimes for extended periods and then overheat at others. In my experience a cracked head, block or leaking head gasket is usually pretty consistent in it's symptoms.

With a thermostat in place the engine would initially start and run normal temp. As I started driving the combustion pressure entering the coolant would gradually cause an air bubble in the cooling system. Once that happened the temp would spike. When I removed the thermostat completely, the pressure had no where to get trapped. Instead it continued to build until the radiator cap released the pressure/coolant via the overflow hose. During testing I would take 5-10 miles drives then check the coolant level. Even after just 5 miles the coolant level would drop considerably.