Thermostats??

[Matt Cole]

What are the factors that allow a water thermostat to function correctly? Is it just water temp to allow it to open or will system pressure/flowrate affect how far the stat opens?? I have tried 3 stats from the clio/megane/16v etc in boiling water and they hardly open. thats including a new one. Now i presume the water has to flow the correct way through it to allow it to open fully?? Discuss.

[RICHIE]

http://en.wikipedia.org/wiki/Thermostats

scroll down mate

[Ashy]

Mat, I've tested Gt ones before and as soon as the water is up to temp they opened fully. If you dropped one in boiling water it would open almost instantly. the 172 one I had took about 3 - 4 mins to open and even then it only opened 1/2 way... Not sure if that ok tho as that article says

"Under normal operating conditions the thermostat is open to about half of its stroke travel, so that it can open further or reduce its opening to react to changes in operating conditions. A correctly designed thermostat will never be fully open or fully closed while the engine is operating normally, or overheating or overcooling would occur. For instance:"