okay just a general question. You know how must thermostat is located in the upper radiator hose. so normal operation. upper radiator hose is hot as the thermostat opens up and lower radiator is returning cooler coolant to the engine so its not as hot.. luke warm. now lets say u have an offbrand vehicle. lets say a vw for instance where the thermostat is located in the lower radiator hose. will the lower be hot and upper hose be cool( not as warm) im assuming thats the way it would work right?

 

Would make sense, the thermostat "controls" coolant temp. in engine, not in the rad, flow would have to be from the engine, but seems to me that pumping water to the top of the rad makes more sense. 94

 

honestly you just lost me there?

 

Every Honda engine I have seen has the thermostat located on the engine end of the lower rad hose. Coolant flows out of the engine via the upper rad hose, and returns from the radiator via the lower hose. Thus, the upper hose is always hot, while the lower hose stays cool until the thermostat opens, at which point it heats up. The lower hose will be a little cooler than the upper hose, but it's often difficult to tell a difference in temperature by hand since they will both feel pretty hot.

 

yes. toyota have the thermostat in the upper radiator hoses. So i was confused. so doesnt really matter where the thermostat is right? both hose will be hot.. just the hose where the thermostat is will tell me if it has opened or not correct?

 

It depends on how the system is designed.

I don't know how the Toyota systems are set up, but if they use a radiator that flows vertically (like the Honda systems do) with the thermostat located on the engine end of the upper rad hose, then both hoses will remain cool until the thermostat opens and the hot coolant then circulates into and out of the rad.

To simplify things, the cooling system is basically just one big closed loop, and the thermostat is the valve that controls circulation. When it is closed (cold), coolant does not circulate. When it is open (hot), coolant circulates. It doesn't really matter if the thermostat is located in the inlet or the outlet of the rad; if it's closed, the coolant won't circulate through the rad.