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Old 04-21-2013, 08:31 AM  
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That's right, it's in the valve cover. You'll need a long extension.

This has to do with thermodynamics. That is your engine temp sensor, and it doesn't matter whether it's in the cylinder head or the thermostat housing- it's measuring the coolant temp. I totally forget what that law is called, but it's what keeps wax filled paper cups burning without melting when floating on water. Heat conducts and dissipates quickly to an equilibrium with all things in contact with the source. Your combustion chambers and exhaust gasses can reach temps over 1500F which is more than enough to melt aluminum. Yet it doesn't because around that aluminum is coolant under pressure flowing through the cylinder head. That acts as a heat sink and pulls excess heat from the combustion chambers out to the radiator where it is cooled off.

Yes, I'm not totally right, it does matter where the temp sensor is located in the cooling system. In the center of the cylinder head is the most efficient place because that's closest to where the majority of heat is being created. In this case, it's a matter of reaction time. Yes, the heat will dissipate and the system will reach equilibrium eventually, but it will change faster closest to the heat.

People who use different terminology are not wrong either. The temp sensor is in the cylinder head- right? It is measuring the cylinder head temp- right? They are only wrong if they think that the cylinder head is hotter than the coolant for more than a split second. The exhaust is, but that's not fluid cooled is it?
Be eclectic.
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