Red triangle and auburn color temp icon warning lights

Your code reader can NOT read the various Prius Specific ECUs and their codes. Time to get mini VCI. Many posts about mini VCI and how to install;helpful if you have a spare 32bit Windows laptop.

If you paid a diagnostic fee, demmand the codes they pulled to come to the conclusionof a new head gasket, otherwise demand a refund.

 

Since you asked.

Do not continue to go for 120 mile mountain drives. Do you have AAA or any other towing service? If you keep driving this car you will end up stranded. A used low millage engine would be a better and cheaper repair than replacing the head gasket in your engine. Use Car-Part.com--Used Auto Parts Market to search junk yards for engines. CA Sports Auto Wrecking in Chula-Vista has a 2007 engine with 76K miles for $450. A good guess would be about $1000 for an independent shop to install.

Brad

 

At that rate you will quickly depreciate any new or new car. Your car is already fully depreciated and in it's current state next to worthless. It would not be silly to find a engine and transmission still together in a low millage wreck. For under $2000 you could reset your drive train to under 100K miles.

Brad

 

A bad thermostat will not cause poor acceleration. A stuck open thermostat will just make your car take longer to heat up. You would still get heat and the car would not display an overheating warning light. The head gasket keeps oil, coolant, and combustion where they belong. It sounds like the seal between combustion and coolant is failing. That will inject gasses into the coolant system. Then you loose heat because pockets of gas will not warm up your heater core. And the temp sensor will read high because there is a lack of coolant to control the temp. Coolant can also enter the cylinders and go tight out the tailpipe. All this can happen without any visible leaks.

Brad

 

1. When you check the engine coolant level, it is not sufficient to look at the reservoir. You must remove the black plastic panel over the radiator and remove the radiator cap so that you can look into the radiator. The fluid level must be at the very top of the radiator neck at all times.
2. When the engine overheating light is on, that is indicative of a serious problem that cannot be ignored. If you've continued to drive the car in that condition, especially 120 miles on mountainous terrain, then the engine probably is permanently damaged by now as overheating caused the engine aluminum components to warp. As previously suggested, installation of a used engine/transaxle is your best bet considering the car's odometer reading - if you intend to keep the car.
3. The engine coolant system probably is not full since you say the cabin heater is not working very well. That is evidence of air trapped in the system.
4. If the thermostat had failed open, then clearly the engine would not overheat. The thermostat is not the problem. If the thermostat had failed closed and there was plenty of engine coolant in the system then the cabin heater would work great.
5. It makes no sense to rebuild a cylinder head on an engine with 270K miles. What about the block, pistons/rings, crankshaft and associated bearings? Those are way past end of life by now.
6. Do you see coolant leaking at the engine coolant pump bearing? If you see a pinkish deposit on the inside of the pulley and on the AC compressor housing, that shows you the pump needed to be replaced - and that may have been the root cause of your engine's problems. If so, it is now too late to replace the pump, the engine needs to be replaced.
7. Assuming the coolant level is low, you are wondering where it is going. a) a faulty head gasket would allow coolant to enter the combustion chambers and be burnt off. b) if the engine coolant pump is leaking, small amounts of coolant will leave the system without depositing on the ground below the car. So unless you pay attention and see the coolant traces on the coolant pump and AC compressor housing, you will not recognize a serious problem exists.

 

On eBay there is an endless supply of used Prius engines from $200 - $500 plus shipping:
prius engine | eBay

autobeyours.com

Your local salvage yards

Look for an independent servicer specializing in Toyota vehicles. Or a servicer specializing in hybrid vehicles. Living in southern CA you should be able to locate a variety of options since Prius are like mushrooms there.

 

Typically a used engine will be guaranteed to work upon arrival. Your remedy would be to obtain a replacement engine or a refund but you would have to absorb the labor costs associated with removing and replacing the engine. What do you expect for a price less than $500?

 

I recall wrecking yards and auto dismantlers charging LESS for shipping to a business address. Have the engine or engine & transaxle shipped to your Prius capable mechanic.

Private Message member "Avi's Advance Automotive". He seems to have a good reputation here. I think he has a shop in Inglewood, CA.

 

I fixed the link. It needed a dot com. Once again Car-Part.com--Used Auto Parts Market .
Brad