The thermostat has 2 functions.

1) To block flow to the radiator when it is cold thus allowing all the coolant to bypass and re-enter the block.

2) To block the bypass circuit allowing all coolant to flow through the radiator when the thermostat is fully open.

Without the thermostat in place, only half the coolant will flow through the radiator when the engine is hot and half will flow through the bypass circuit since the thermostat will not be there to restrict the bypass circuit.

The end result is the car will run warmer without the thermostat.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record