Coolant temperature?

Question

my in-dash coolant temperature reader doesn't work so I bought an aftermarket thermometer. No wires, just a probe connected to the thermo.
On a short drive in 70 degree weather it was at 180 degrees F. Parked the car for about 15 minutes, drove to the store and it went up to 211 degrees F.

Is my engine too hot? Fluid levels are good & clean.
What's going on?

Answer 1

Depending on the vehicle 180-210 deg F is normal operating temp.

Answer 2

You don't say what make/model of car you've got, so whether 180 or 210 would be considered normal is up for grabs. Most thermostats will open up within that range.

It's entirely possible that first "short drive" never got the engine fully up to temperature. "Heat soak" (heat from the block being dissipated into the coolant while it sat parked) could easily account for an increase in the temperature you read when you got back into the car.

Your description of your installation also makes me wonder what you connected to what. Understand that the original gauge was designed to work with a particular sensor/sender unit and was calibrated accordingly. If you tried to hook in an aftermarket gauge to the existing wiring, the two may not work together to produce the right readings.

Alternately, if your new gauge came with its own sender unit, that's good, but when you said "no wires", and "just a probe", it's hard to know what you've got. Did this thing come with its own "probe", and if so, where did you place it in/on the engine???

Last, realize that the quality of both gauges and sender units varies a good bit, and the accuracy isn't perfect. They're better at telling you if there's something unusual compared to your normal reading (whatever it is), but I'd hesitate to depend upon them for an absolute reading.

Answer 3

Your perfectly fine. While you run down the road the wind through the radiator plus the cooling fan pulling air through it provides optimum cooling. When you stop the engine the water pump no longer turns to circulate the coolant. Any coolant that remains in the radiator is not cooled. The hot water is trapped. Do not worry, your 15 pressure cap will not allow coolant to boil till it reached over 260 degrees farenheight. No damage will be done to your motor.