08. With 182K miles, coolant high temp warning flashes intermittently after 10 mins of driving over 50 mph. If I put heater on it blows cold air. Had to add 1/2 gal to radiator directly , other reservoirs ok. Problem not as frequent the cooler the ambient air, but still there
You might have a leaking water pump, confirm it's condition and condition of the belt it's attached to, change if needed. For now top off the coolant in the radiator every morning until you see it full and doesn't require topping up. It's also a good idea to change the radiator cap too
Yeah. Start with cap and pump. I just went through the same with my 08. 2 Toyota dealers, first says nothing wrong and 2nd replaced new radiator cap again for $137. Blown head gasket. Put a funnel in the radiator neck and leave the car on with the ac on. The bubbles that come out of the funnel will tell you everything. When bubbles come out, sniff them for exhaust. If you smell exhaust fumes bubbling out with the radiator cap off, you'll know it's curtains for your prius.
