@ calibrator... i guess that my experience in the IT business obviously counts for shit-all then!
i am obviously also taking from experiences that i've had in the motor industry, and i was trying to repeat an explanation that i got from an established mechanic once.
i also did a quick search on Wiki, and i got a response exactly like the one i tried to explain:
regardless - here is where i am coming from:Wikipedia wrote: A fan clutch is an automatic device frequently used in automotive cooling systems. When the engine is cool or even at normal operating temperature, the fan clutch partially disengages the engine's mechanically-driven radiator cooling fan, generally located at the front of the water pump and driven by a belt and pulley connected to the engine's crankshaft. This saves power since the engine does not have to fully drive the fan.
However, if engine temperature climbs beyond the clutch's pre-determined setting, the fan becomes fully engaged, thus maintaining or lowering engine temperature.
Most fan clutches are viscous or "fluid" couplings combined with a bi-metallic sensory system similar to that in a thermostat.
1. you're right about the fluid in the coupling being silicone. and one property of THAT silicone is that the hotter it gets the more solid it becomes. in fact, it gets very close to being a near complete solid. so it makes sense that when the silicone between the coupling's plates is cold, the plates slip over each other. when it gets hotter, the silicone basically glues those plates together as it gets closer to becoming a solid.
2. it was a mercedes benz, if i am not mistaken, that i was describing. that was the car where the fan was barely spinning while things were cold. at that stage you could stop the blades with you hands and the engine would carry on idling. in fact, the fan would barely spin even if you revved the engine. but the hotter the engine got, the faster the blades would spin. so unless it was some drug that someone had slipped into my drink, that is what i experienced. but perhaps the germans do things differently to the japs.
3. i had never actually thought that deeply about the direction of flow of the water, but now that you mention it - it makes sense (i guess) to switch on the fans based on the temperature of the hot side. it also makes sense that the radiator fills from the bottom and runs towards the engine from the top. however...
4. i have never had any problems with the running temperatures of my ca18det. NEVER. so i wouldnt go as far as calling it a FUCKUP. my engine used to run at halfway on the stock temp gauge. which is what is recommended by the FSM. since i removed the aircon system it now runs ever so slightly below that halfway line??? go figure!!! i hope thats not to much of a fuckup either.
5. i would assume that when the water temperature switch turns the fans on, that the water flowing into the engine would be about 91 degrees celcius. i assume this because i hope that the thermostat is working properly, and at that temperature would therefore be open about 10 degrees prior to this. my assumption leads me to believe that the engine is operating at roughly the right temperature, which i believe to be about 100 degrees. i hope that is right, because i'm not about to go to my garage to get out my FSM now!
6. lastly, even on the drift track, my stock water temp needle stays just below the half mark. the water temp guessometer i have installed barely ever reads over 100 degrees. but dont forget thats on the cold side!
