Prius 3 2014 204K miles

Were the intake manifold (has EGR passages) and EGR components cleaned in the course of the engine replacement? If not, they’ll be more-or-less completely carbon-blocked by now, should definitely be cleaned, and recleaned at least every 50k miles.

My 2 cents: neglected EGR cleaning is why you’re on a second engine.

see top two links in my signature; on a phone turn it landscape to see signatures.

 

It's not just the EGR valve that needs to be cleaned it's the whole system, but to me it seems more likely to be related to using head gasket sealer than a clogged EGR system. The radiator or the water pump could be gunked up.

 

nothing wrong with that, that's what a dealer would do

 

The egr could be completely blocked and the engine coolant temperature won’t change. Odds are good you have reduced radiator capacity after using the sealant.

 

OK, good luck with it.

 

I do believe the original specifications of that car allows you to travel faster than 70 mph, without overheating.

IMHO; you should save your $100 and plan on another engine replacement when you blow your current engine. Peace-meal solutions rarely work, in the long run - It can buy you some time, but that's it. ie. head gasket sealant and all the other head-aches they cause; but it's your money and car. We can only suggest what can fix your car permanently! It up to you to take the suggestion or reject it.

Peace....

 

A pressure test of the radiator does not prove it is not partially clogged up. A partially clogged radiator will work at normal loads experienced by legal speeds (except in central Texas on the 85mph tollway)

The valve is not the egr component that clogs up. Most people don’t even clean it. It’s the egr cooler ($300 part) and the egr passages on the intake manifold ($200 part). Not saying replacing the egr valve and updating the ecm software is not a good idea but none of the egr components will solve overheating.

 

A pressure test will ONLY tell you if the cooling system leaking, since it passed - congratulations you don't have a leak. Why did you think that test would mean that your cooling system isn't clogged or obstructed?
I'd start with the radiator and check the water pump signal for additional spin-up when she gets hot. Radiator and heater element passages are very narrow, so head gasket sealant is likely to clog them.
Make sure your cooling fans are working also, prevents overheating in stop & go traffic - not so much at highway speeds.

Hope this helps....

 

Conventional Priuschat wisdom is a clogged egr system may cause a blown head gasket. Possibly because the egr passages in the intake are unevenly clogged.

Overheating is rarely an issue with these cars unless the cooling system is clogged or the water pump is failing. If the water pump you used was not supplied by a dealer there is a good chance it was aftermarket or counterfeit.

I would probably change the water pump and thermostat again unless it was from a dealer. While I was at it I would change the coolant.

I would monitor the coolant temp in realtime to actually know what it’s doing. Normally the car using AC should run about 190f with occasional short spikes to 205f when accelerating up a steep hill. I haver never seen over 210f in my central Texas experience over the last five years.

If you see the warning light flash it was at 248f or higher.

If the water pump and thermostat does not clear up overheating I would replace the radiator.

 

One manufacturer of stop-leak “product” recommends 50/50 vinegar/water flush, presumably followed by straight water flushes. There’s a link in my signature, thoughts how to achieve 50/50 coolant/water ratio in aftermath of such flush. (On a phone turn it landscape to see signatures.)

 

Dr Prius app is not the best free app to read trouble codes. Download the Car Scanner ELM OBD2 app to read the codes.

 

you can look in the inverter coolant reservoir to see if there is any movement when the car is on

 

It doesn't always circulate. Only when it starts to heat up. Which is fairly quick.
Since you are loosing coolant for the inverter, look for leaks. And any evidence of it
overspilling the tank.
You'll pretty much have to remove the inverter to replace the pump.