2011 Prius Overheating issue coolant reservoir getting hot and red temp light turning on

New engine, or what they refer to as new-to-me engine?

 

I wonder if there was a mistake made when replacement engine was installed? One time a someone on here found a bolt clogging one of his coolant lines. How many miles of normal operation, if any, after engine was replaced?

 

Since you don’t really know the history on the car I don’t know exactly what’s going on but I would make an educated guess that the previous engine/ engine coolant had head gasket sealer in the coolant based on the fact that the engine was replaced. They really only replace engines when the head gasket fails unless you drive the failed head gasket until the piston shoots out of the block. Then you definitely need a new engine. I would say replace the engine radiator first because how would the inverter coolant pump affect it unless you are getting specific codes for the inverter. This is what the head gasket sealer looks like in the coolant after being in the car for some time.

 

I like what you're saying here... But what's still confusing is that when an inverter pump fails the warning lights don't come on just because the pump is not working, they come on after the invert recognizes that it's running too hot. And why would that error code not come up if the system is clearly running hot? Or maybe it is and I misunderstood?

 

Yes I do not completely understand the inverter failure symptoms but I would check the inverter coolant pump to see if it circulates fluid in ready mode. I would not rule out the inverter pump until having someone look at it but a mechanic will do the work replacing it whether it is needed or not…Also read the codes if you can it would help.

edit: just saw no codes in the OP

 

I wonder if OP is not being clear enough about when warning lights/error codes happen? Because if your inverter coolant gets too hot the car is gonna throw a red triangle and as the situation gets worse the car will shut off the hybrid system entirely, which would be consistent with loss of power on freeway and coolant reservoir being hot? But as I read their description the inverter coolant is super hot and there's less power on the freeway but there's no dash lights / error codes. That doesn't make sense?

 

Engine speed for peak power, for peak torque, for peak engine efficiency, and for peak car mpg in some specific circumstances are 4 separate speeds. There's no reason to expect them to be identical.

 

First and foremost quit driving a gen3 that is overheating. A "new" engine either means a new to me used engine or a rebuilt used engine. Both could have counterfeit or otherwise bad water pumps.

If you must continue driving at least get a monitor for coolant temps. I suspect you are driving at too high temps all the time but just break alarm thresholds on high speed hills.

I continually monitor engine temp with a low cost (-$30) P10 scanner which allows user set alarms.



I can quickly switch to a bluetooth obd2 scanner ($32) feeding the "Car Scanner" app which is also highly configurable.



Since it is on your phone it is easy to record a drive and review later if desired.

 

Stop leak should be called stop FLOW.... It's HORRIBLE crap and should NEVER
be used unless you intend to replace coolant related parts.
Also remember that the small coolant passages in the engine block get clogged also.
Sometime in the near future you might want to also back flush your heater core with
white vineager to unclog that also.

And maybe cleaning off the coolant temp sensors...

 

50/50 mix of white vinegar and water was recommended by one of the stop-leak manufacturers. There’s a link in my signature with some thoughts on how to do this.

 

Pretty sure he bought the 2011 recently. He bought a 2005 back in 2018 so this one was probably a head gasket case temporarily repaired by a scammer using input from Priuschat. Its a problem and is the number one reason I try to discourage people considering a gen3.