I'm in phoenix, arizona. I have a 2015 prius 3. The coolant was leaking so I took it into a mechanic and he put in block seal. Do you think that will ruin anything? The problem is, the red overheat light comes on approximately once every other week. I put the car in neutral as fast as I see it, pull over and turn the car off. I open the hood and see some coolant has sprayed out from the reservoir. I get back in the car, start it and the light turns off. The car drives normal and the overheat light stays off. Anyone know what the problem could be? Thank you in advance!
How many miles on it? If the water pump is not working correctly, the engine will overheat. That's why the coolant is spraying out. You need to have it checked and replaced if it's bad. Another reason could be a bad thermostat that's sticking. Possibly the coolant fans aren't working. When does it over heat? Idling, low speeds, highway speeds?
How many miles? While there's no service interval for replacement, the concensus here seem to be it's wise to replace the water pump (engine coolant pump) around 100~150K miles. It has a plastic impeller, that gradually swells, gets harder to turn. Have you ever cleaned the intake manifold and EGR system? When it's clogging, and head gasket going, one symptom is increased coolant system pressure.