07-16-2009, 06:54 PM
contrary to popular opinion, you CANNOT test your thermostat by tossing it into a pot of water and seeing where it pops
thermostats are controlled by coiled copper wires that heat at a consistent rate - what this means is that as the heat rises, the wire expands, thereby opening the thermostat - this happens at a fairly gradual rate though, and when the temp drops, it closes again - this cycle continues as the engine runs - further more, it is not an "on/off" situation - the thermostat will begin to open at one temp, and be fully open at another - this is by design and to promote a more even running temperature - if it were simply open and closed, and no partially open position, wider temperature swings would occur, and stress materials more
the problem with tossing it in a pot of water for testing is basically twofold
1. it cannot be allowed to touch the pot - it must be insulated from the metal, as the metal is ALWAYS hotter than the water, and will conduct that heat directly to the thermostat, giving you a false reading of the temperature affecting it - there is also always heat loss as the heat passes through the water - you must expose the thermostat ONLY to the liquid
2. unless you plan on running straight water, testing it in straight water will not give you an accurate reading on where it will open - antifreeze extends the temperature range - if the thermostat is opening at 185 on your stove, it may not open until 195 in your car
3. similar to number 2, your cooling system is under pressure - this also affects the temperature at which the thermostat will open
to properly test your thermostat:
1. place a pot of coolant mixed the same as you plan to run on the stove
2. bring it up to about 20-30 degrees below the indicated temperature setting of the thermostat
3. using something non-metallic to suspend the thermostat in the pot, dip the thermostat in the coolant
4. using a good thermometer to monitor, gradually increase the heat to bring the temperature up to the point at which the thermostat BEGINS to open - note this temp
5. continue to increase the temp until the thermostat is fully open - note this temp
6. allow to cool down, noting the temperature when the thermostat is fully closed
7. REPEAT process twice
VERY IMPORTANT - dispose of the pot, or store safely away from children and pets - it is NOT SAFE to use for food ever again
thermostats are controlled by coiled copper wires that heat at a consistent rate - what this means is that as the heat rises, the wire expands, thereby opening the thermostat - this happens at a fairly gradual rate though, and when the temp drops, it closes again - this cycle continues as the engine runs - further more, it is not an "on/off" situation - the thermostat will begin to open at one temp, and be fully open at another - this is by design and to promote a more even running temperature - if it were simply open and closed, and no partially open position, wider temperature swings would occur, and stress materials more
the problem with tossing it in a pot of water for testing is basically twofold
1. it cannot be allowed to touch the pot - it must be insulated from the metal, as the metal is ALWAYS hotter than the water, and will conduct that heat directly to the thermostat, giving you a false reading of the temperature affecting it - there is also always heat loss as the heat passes through the water - you must expose the thermostat ONLY to the liquid
2. unless you plan on running straight water, testing it in straight water will not give you an accurate reading on where it will open - antifreeze extends the temperature range - if the thermostat is opening at 185 on your stove, it may not open until 195 in your car
3. similar to number 2, your cooling system is under pressure - this also affects the temperature at which the thermostat will open
to properly test your thermostat:
1. place a pot of coolant mixed the same as you plan to run on the stove
2. bring it up to about 20-30 degrees below the indicated temperature setting of the thermostat
3. using something non-metallic to suspend the thermostat in the pot, dip the thermostat in the coolant
4. using a good thermometer to monitor, gradually increase the heat to bring the temperature up to the point at which the thermostat BEGINS to open - note this temp
5. continue to increase the temp until the thermostat is fully open - note this temp
6. allow to cool down, noting the temperature when the thermostat is fully closed
7. REPEAT process twice
VERY IMPORTANT - dispose of the pot, or store safely away from children and pets - it is NOT SAFE to use for food ever again
94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com
"It isn't nearly as expensive to do it right as it is to do it wrong."
(This post was last modified: 07-16-2009, 06:55 PM by flash.)