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Coolant Temperature in Radiator

I’d like to know the typical temperature that the engine coolant liquid itself (propylene glycol) is at when it first enters the radiator.

All help is appreciated,


That would depend on the temperature at which the thermostat opens. 190-210 degrees fahrenheit is a good range for modern cars.

190 is probably the lowest. Many cooling fans are set to kick on at the 230-240F degree range. So for most cars where everything works, I’d say anything between about 200-240F

When it first goes in, it will likely be at the temperature is where it has been sitting on the shelf before you bought it. ?

Interesting question. Coolant at the T-stat, coming out of the engine, would typically be expected to be about 220 or so degrees, but after the heat has been removed via the radiator it should be between that and the air’s ambient temperature. I’m going to posit a wild gues of perhaps 100 degrees, but it’s just a guess.

And there’s a caveat to even that guess. When I lived in North Dakota, we used to have to put cardboard in front of the radiators to get the engine to reach operating temperature. The air passing through the radiator at speed would remove the heat from the coolant faster than the engine was putting it in. In subzero temps, the coolant coming out of the radiator would be much colder than it would be in 80 degrees F.

It’d be easy to find out if you know someone with a pyrometer.