How much time is needed to determine if coolant is circulating?

[gruntsey]

How long do I have to run the engine ,with the heater on and the coolant resevoir cap off, in order to get the coolant to circulate? I let it run until the gauge showed approximately 195 (where it is supposed to be) , but the upper radiator hose never got warm.

Also, if the new thermostat I just put in recently is stuck closed, how can I tell for sure if the engine is not overheating?

[fredjacksonsan]

Usually about 20 minutes will do it, if it's warm outside. It may take a little longer. The radiator hose might not get warm, but the coolant inside the radiator will; you can stick your finger in the radiator quickly to check the temp. Also, if it's cooler outside look for steam coming from the radiator (all this assumes you are doing this with the cap OFF)

If the new thermostat is stuck closed, you will see the problem on your temperature gauge. But again, if you're getting hotter coolant in the radiator, the thermostat has to be opening.

[gruntsey]

Thank you for your reply ...I realize now that I didn't let the engine run long enough.

I did take it out for a drive around town today and when I got back I could feel the heat in the hose. All is good.