temp gauge question (engine/water)

[mister_big_bird]

Guys,

Forgive me for my ignorance. Yung temp gauge ba sa dash is temperature ng engine ? or temp ng coolant/water flowing in the engine ?

San part kaya ng engine ko yung sensor nato. Its a 94 honda esi.

thanks,
MBB

[kinyo]

the sensor is located underneath the distributor assembly ... normally hidden from view but you can see the wire going into it

it directly senses the coolant temperature inside the engine which is, of course, an indirect representation of the engine's temperature ... and if ever the coolant disappears, the sensor will still register the engine's (increased) temperature via its metallic body bolted to the engine

[mister_big_bird]

thanks kinyo, nicely explained.

[speedyfix]

its the water temp that it measures. oil temps usually follow the change in the water temp but in extreme case such as racing, individual gauges are necessary to keep a close eye on each one.

[mister_big_bird]

if its the water temp its measuring, then your saying that when my gauge reach "H" the water temperature is about 100 deg. cels. cause water can go beyond that, right ? but then again accdg to the manual, the thermostat opens at around 77+ deg cels. on which only about 1/3 on my gauge ???? care to comment ?

[mister_big_bird]

>if its the water temp its measuring, then your >saying that when my gauge reach "H" the >water temperature is about 100 deg. cels. >cause water can go beyond that, right ? >but >then again accdg to the manual, the >thermostat opens at around 77+ deg cels. >on which only about 1/3 on my gauge ???? >care to comment ?

can't go beyond 100 deg celsius pala, mistype lang

[kinyo]

it is possible for water inside the engine to go higher than 100 celsius without boiling because it is under pressure (above atmospheric pressure) ... for example, at 15 psi (above atmosphere) water boils at 127 celsius ... mixed with coolant, the combination even have a higher boiling point

in a normal engine (no leaks), the water never reach boiling temperature ... the temperature gauge, if it would be labeled with temperature, may have 50 celsius at the lowest mark, 90 at the middle and 110 at the top mark ... kinda non-linear because the sensor itself is non-linear

if the thermostat starts to open at 77 celsius, it becomes fully open at few degrees higher, say 80 ... and then the temperature will stabilize at few more degrees higher, say 85, which might be indicated as 1/3 mark on your gauge ... although the water is not boiling at 85 celsius in a running engine, it is under pressure (!) so that if you open the radiator cap ... well, you know what will happen

[mister_big_bird]

thanks kinyo. fully understood.