healeyman Report post Posted April 10, 2011 I have a long running debate with several friends. One side says that an engine thermostat is essential to keep an engine WARM. The other side says that an engine thermostat is essential to keep an engine COOL. WHAT do YOU think and WHY? Tim Share this post Link to post Share on other sites
dwightginnyputzke Report post Posted April 10, 2011 I think its long past your bed time. That's why. Share this post Link to post Share on other sites
jrwitt Report post Posted April 10, 2011 The basic purpose of a thermostat is to keep the engine operating within the proper temperature range. If the engine is cold, the thermostat slows the flow of cooling water until the engine warms up. If the engine starts running hot, the thermostat opens up and allows more of the cooling water to keep the engine within its proper temperature range. I guess that means that both sides are correct. I agree with Dwight! And I will add that you guys sound like engineering students at Yale! Stop concentrating on one isolated area of the discussion and look at the whole picture. Duh? Share this post Link to post Share on other sites
mclavey Report post Posted April 22, 2011 I have not laughed this hard in a long time . LOL LOL LOL Share this post Link to post Share on other sites
Spike45 Report post Posted June 21, 2011 I have a long running debate with several friends. One side says that an engine thermostat is essential to keep an engine WARM. The other side says that an engine thermostat is essential to keep an engine COOL. WHAT do YOU think and WHY? Tim This is not what I think. It is what I know per Cummins. Thermostats are used to maintain MINIMUM engine operating temperatures. Maximum engine temperatures are controlled by your foot on the pedal, the grade, the weight of the toad, head wind speed.....in short, the loading on your engine. The sensing bulb in the thermostat only responds to increases in jacket coolant temperature. When sufficient temperatures are reached (the marked temp on the stat), it begins to open. For example, a thermostat is marked "180". It begins to open (cracks) at 180F, and is fully open, if you are working the engine hard enough, at 202F. If you are not working the engine sufficiently, the temperature remains near the crack open temp. In this manner the thermostat controls minimum operating temperature. Under the right conditions, the thermostat may not open at all but still the engine does not overheat. One such instance is in arctic-like temperatures where there is sufficient fan air blowing on the engine, the thermostat may not open as the engine is being cooled by the air on the block. In that instance, the thermostat is trying to maintain the minimum operating temperature set by the OEM engine company. It is doubtful you will experience that but may come close in Winter driving. In hot weather driving with sufficient loading, the thermostat will open completely sending all coolant to the radiator vs being partially open and recirculating a portion of the coolant back to the engine for additional heating. Once the thermostat is fully open it no longer is in control of the jacket temperature (other than minimum). Your pressing on the throttle pedal causes more fuel delivery, more heat rejection to the radiator, and elevating temperatures. You may experience that while climbing mountain passes in higher gears in the transmission. While the engine certainly has the torque to keep chugging up the hill, the engine speed is slowing, the water pump slows down, the fan slows down and the heat load is going up.......you see the temp gauge go up above 200F. If you are watching the exhaust gas pyrometer, you no doubt, will see the EGT climb over 1000F. Share this post Link to post Share on other sites
