So I have a 2012 Prius c with 191k miles that started overheating when going 60-70 mph last year. There were no lights on the dash until overheat, it ran fine otherwise. It was not low on coolant. I brought it to my local dealership, they said they couldn't find any leaks in the head gasket, but replaced some hoses and the thermostat housing. It ran fine for a year then just had the issue again, now they say the head gasket is leaking in the back. They want to charge me more than I think the car is worth so I'd like opinions on if it's worth it to fix, and if there's any sort of guide out there as I'm not that mechanically inclined but can follow guides and my dad has worked on cars but only 2000s and older so not as many electronics.
Well, a dealer is a really terrible service option for a 10+ year old car. Get a second opinion from an independent shop. A head gasket job in one of these isn't much different than any other compact car with an inline engine. Personally I'd be suspicious of the water pump- they can lose pumping capacity over time without really giving much warning until something expensive happens. Out of curiosity, where are you on the coolant replacement schedule? It does need periodic replacement to control internal corrosion.
+1 ^ the intermittent nature of the failure would suggest that electric water pump impeller is hanging up or can't keep up with the flow demand from the ECU. If the thermostat wasn't opening up all the way that could cause your overheat also, but changing hoses isn't going to fix an overheat issue, unless it was plugged. If that was the case, you'd have bigger problems...... Then again, those previous overheats could've damaged the head gasket enough for it to fail on you. That's a known issue on gen3s. The temperature lamp lights up around 240F, normal engine operations is around 190F, so when that lamp flashes at you - you don't know how long the car has been running too hot. There's a lot of plastics in that engine, heat and plastic usually don't mix well. Good Luck...
^+1. My guess is also the engine water pump.You should buy an OBD22 dongle and use an app to monitor the coolant temperature. If the coolant temperature is going higher than 202F, it is time to replace the water pump.
Thanks for the ideas and replies, I'll look into getting a OBD2 dongle, and seeing what the readings are, and checking out the water pump. I'm not sure when the coolant was replaced however the previous owner is family and she doesn't know cars but will only take cars to the dealership and will follow any and all recommendations for service. It was also always stored in a garag until I bought it 2 years ago, I've only put about 3k miles on it.
