Radiator cap, or fans not coming on
Hi there,
This is basic sign here that one of 2 things are happening.
First, radiator caps hold pressure inside the cooling system, which raises the boiling point of the coolant. Now, if the radiator cap is not exerting enough pressure, than it could boil over into the overflow tank.
Second, if the fans are not coming on at 228, your pressure could be over the cap, and push past the spring, causing this condition.
What I would suggest here is that you ask for another test drive, this time, take attention of the temperature of the engine. Highway speeds, it should be no higher than 200, in the city, it should not get past 230.
The cooling fans are very efficient, and should cool the car down quickly.
There also might be debris in the radiator, causing less airflow through the area, so it doesnt cool as effectively. If you temp is higher than 200 on the highway, this could be your issue.
Best to you, c4c5