I have a 2013 Prius 3. 160k. Has been maintained. Has a 50k engine that was installed by a shop about 6 months ago. Has had no problems since. Yesterday noticed there was no heat on way home. Temperature light came on. I was able to put prius in ev mode and continue 3 blocks to autozone. Opened hood and noticed coolant all over drivers side of engine. Refilled reservoir tank and made it 2 miles to home. Light came on again a few blocks from home. Pulled over added coolant and made it home. Today found coolant line (#16264) had 2 cracks in line. Replaced refilled reservoir. Put car in maintenance mode and let run with radiator cap off and funnel in opening to try to “burp” the engine. I even raised reservoir tank above engine. Coolant keeps overflowing back out of the reservoir after engine heats up and fans kick on. Went through 2 gallons. Heat still does not work. Car overheat warning light comes on when taken for a test drive. I can pull over, wait 1 mins, and then drive again for about 5 mins before light will come back. System seems to have an immense amount of pressure. Once pressure is released by opening cap a little, will work again temporarily. Hose heading to heater core is hot and pressurized but return line is cold and not pressurized. Was planning on temporarily removing heater core from loop to see if it will stop over heating. Any help you can offer would be appreciated.
Also, noticed that the radiator hose with the ECT is hot and pressurized. The return line fills empty and is cold.
Was a stop-leak product used prior to this? Presume head gasket failure? Any EGR cleanings? At what miles?
Your engine water pump has probably gone bad. Replace it ASAP before you drive the car anymore. OEM water pump is my recommendation. Edit: The other possibility is that the thermostat is stuck closed. My bet is that the water pump is bad.
Also, while thermostats are super reliable and often last the life of a car, one good episode of overheating can often kill one. The expanding wax that makes it open expands so much it bursts right out, then that thermostat won't be opening anymore. Even if it wasn't the reason for the first overheating, it will be the reason from then on, until replaced.
