2011 Prius high coolant temperature and check hybrid system

Without miles driven on engine, maintenance history and CEL codes as a great guide, you might just have to start swapping random parts in and out on your list to resolve the issue.

 

"I didnt pay much attention to it." THAT is never a good idea!
Then continuing to drive it? Double never a good idea. For any gas engine.

You should have it towed back to the place that did the head.
Maybe they didn't fill the coolant enough or correctly. Is it low? Is there air in the system?

Did they replace the head? Or only machine it, and you replaced the head?
Was it running before you had the head done? Did it over heat? And why?
Did they head gasket fail? And why? Have you cleaned the EGR System?

The inverter could be a seperate issue.

You are not giving enough information to give you a good answer.

 

I'd first be checking to make sure it has enough coolant and that there is not air in the system. If you can confirm it is full I'd be making sure that it is not loosing coolant over time.

I've had other cars (not a Prius) with blown head gasgets and they behaved simularily. Sometimes overheating, but not always - very intermittant and usually after a long drive or fast driving, but then even long trips around town or low speed highway driving no problems at all. A temporary fix was to add back in coolant. But then it would keep loosing coolant because the head gasget was blown. I drove a Subaru with a blown head gasget 1000's of miles with it overheating like this intermittantly and adding coolant when needed before I got it fixed. But also your symptoms could simply be from not enough coolant filled back up or air bubbles in the system - there may be a very simple fix to this.

I also drove a Chevy from work that had low coolant but not a blown head gasget and it behaved the same, showing overheating and then the next minute showing that temp was fine. Mechanic told me that where the thermometer was would only work if it was touching coolant. I guess if there was too much air it wasnt sensing the temperature and then it would look like temp was low but actually it was overheating.

I agree that you might want to take it back to the people that did the last repair - they may have done something wrong.

But I also agree, it could also be the water pump or a number of other parts that could have failed. Will need more investigation to confirm. Start with the simplest, easiest things to confirm, and move through them methodically, or take it to a mechanic that can do this for you.

How many miles are on the car? If it is more than 120,000 miles and the EGR system hasn't ever been cleaned (if you dont know the history of the vehicle I'd assume that it hasnt been cleaned) that could be causing problems, but it also might not be the cause of the problem. There are plenty of threads about that on here. Regardless I'd be doing the full EGR system clean as a preventative maintenance item on a used car to get long life out of it.

 

Its a good thing to do to ensure long life of vehicle, but having a clean EGR wont solve your current overheating problems. Something else is going on here.

 

Don't beat ourself up over it, we have all done thing that aren't to bright.
Like Rocky Moutain Priusman sad, you probably have air in the system.

There is a bleed valve on the hoses by the brake master cylinder, open that, then fill slowly.
A little at a time, it give it time to settle and push the air out. If you don't have the valve,
you can pull off the highest hose, just watch for the coolant to come out, then reinstall it.
Squeeze the radiator hoses several times, that helps push the air out.
A lot of people seem to have this problem after replacing the head gasket, or changing coolant.
The key is to fill slowly.

While the head was off, that was a good time to clean the intake manifold and egr cooler.
But it's not a huge deal to do it since the head is back on.

 

I had the same issue after I had my head gasket rebuilt. I change the thermostat and water pump. Issue went away. My friend had the same issue and I told him to do the same thing. Told him he can buy the parts on amazon asisn that are the same has toyota oem. His issue went away.

 

Engine coolant pump or the inverter coolant pump? I've replaced both, inverter pump is oem. Engine pump is aftermarket along with thermostat. Mg1/2 can easily go above 250... Will try to bleed all again.

 

If an MG temperature is what concerns you, then the pump in question would be the inverter one.

 

yeah, that's why I replaced it a few hours ago and temps are still high... just used techstream to clear the air, about to see if that helped.

 

Are the elevated temperatures the MG1/MG2 temperatures, or the MG1/MG2 inverter temperatures?

There have been reports of the coolant passages in the inverter getting deposits of glop sometimes.

 

MG

 

How do you clean it out? Is that how I read someone violently shaking the inverter?

 

I don't imagine there's any easy way.

I suspect the glop is the kind of jelly that wet aluminum oxide forms into, and maybe backflushing the IPM somehow would help, with or without something that dissolves that glop, whatever that may be.

I don't even know of an easy way to find out if that condition exists. Comparing flow at a known regulated pressure through a new IPM and the questionable one is about all I can think of.

People who have seen the glop have usually been those destructively dismantling the inverter to see how it ticks, but that won't appeal to everybody.

 

since my mg's for the inverter is fine for now, need to test on a hill climb. What would cause mg temps to go high? assuming over 200 is high right? what do the mg temps relate to?

 

I think there's a thermistor in the windings of each MG.

For normal ranges, maybe you could borrow another Prius without any known issues, and compare its MG temps on a similar hill climb?