[D13]

Originally Posted by Gregski

yes gentlemen the 180* T stat comes with a 1/8th hole pre drilled I can't help but think of and compare this to the "designer" jeans with the pre torn holes in their knees that cost $80 bucks where regular good ol' fashioned Mexican Levis 505s cost only $20 lol

That hole is to prevent an air lock. If the thermostat seals well you can trap an air bubble behind it, then the thermosat does not see a 'wet' hot condition and may not open in a timely fashion. The classic symptoms of this is poor heater performance (since flow is impaired) and high engine temperature (since the temp sensor is often below the trapped air bubble, and / or not at the thermostat), or on fuel injected cars using dual sensors, poor performance (car knows its hot and starts adding fuel and pulling timing... but the gauge says all is good). This is particularly common on the first fill and break in start up which is why 'some' people recommend no thermostat (FYI that is the wrong answer for anything but a drag car that is going to go get a hose stuck in it for cooldown. Engines like to run at a steady temeprature where they can be tuned for efficiency). Back in the day I improved cooling performance or driveability on many a car by drilling that small hole to allow air to self purge.