Prius overheating and coolant and engine!

it's very likely a blown head gasket (common problem) and my opinion is get what you can for it and move on.

 

The magic fix with spark plugs is common and leads to disappointment on gen3. Odds are 90% the water pump was ok. Shotgunning the parts cannon. The reality is the leak initially seals itself but people waste money with old school fixes on these engines.

For that money or a tad more I would want a rebuilt engine with new pistons. Unless you are fixing it to sell without taking a giant hit as is.

Check the hv battery. 13 years old and sitting for a year (why do people do this) is bad news. Brake booster potential as well. Another $5k if those two are original.

 

Rebuilt is a good used engine completely disassembled, major parts inspected, machined or replaced especially the pistons, rings and heads on these engines. Other failed parts are also replaced. All new seals and gaskets are installed including the head gasket. Effectively looks new and acts new when done. No oil burning, no leaks and effectively cleaned air, pcv and egr passages.

A used engine is simply pulled out of a junked car, rarely has any way to verify miles and is simply dropped into your car. Its a crap shoot only slightly mitigated by the honor of your shop when it fails. Which is often way too soon. A new manifold gasket is the intake manifold gasket, not a head gasket. Your shop may pay $1500 for a used engine and swap it in 4 to 8 manhours. If you were doing it for yourself and wanted to keep the cost close to $1500 then ok. Used may be better than yours but rebuilt is what I would want.

 

Ensure the EGR components and intake manifold (has EGR passages) are thoroughly cleaned in the repair process. See the mechanics you're working with have proposed to do this, which is good.

My 2 cents: it's a lack of periodic (say every 50K miles) cleaning that directly lead to your engine's demise. 3rd gen owners were guinea pigs with the new EGR system Toyota implemented, and now Toyota doesn't want to deal with the outcome.

See first two links in my signature. On a phone, turn it landscape to see signatures.

 

I have similar issues with my Prius. I have a 2011. Changed out engine, water pump, sensor and thermostat. I have issue when I drive high speeds 70-80 mph up hill. Reservoir very hot almost to boiling temperature. Temp red light would turn on or flash and then when I slow down it will eventually turn off. My mechanic replaced literally everything minus the radiator and the inverter coolant pump. Can anyone please help????

No codes or no check engine lights just the red light engine temperature turns on when driving high speeds up hill for long periods of time.

Is the issue temp sensor on EGR pipes?

My mechanic has replaced with all OEM parts. Any advice?

Toyota service rep says might be inverter water pump, radiator clogged up, or water pump.
Just had Toyota dealership diagnosed and they check for any leaks so it’s not the engine. They said water pump and thermostat. My mechanic replaced those 2 parts. I thought I was in the clear but I wasn’t. The car still overheats when driving high speeds 75-80 mph for long periods of time and red temperature light turns on again uphill at high speeds. Anyone please help and TIA

 

Possible counterfeit oem water pump.

 

I had the same problem, two seperate aisin installs bought off amazon... when I did this change to the OEM pump, all has been good without issues!

https://black.jmyntrn.com/2022/12/15/toyota-prius-engine-water-pump-fix-not-replace/

 

Assuming it is the head gasket, that's a good price for a used low mileage engine install. If you want to keep the car, I'd go for it. If you sold the vehicle as is, you wouldn't get squat for it anyway with it having a blown head gasket.