Red triangle and red thermometer

The repair shop probably did not bleed out all of the air properly and air pockets are causing the engine to overheat.

Find another repair shop more familiar with the Prius and have them get all of the air out and soon. A blown head gasket might be your next problem if you don't.

 

welcome to priuschat! how many miles on her?

 

make sure they understand the difficulties in purging the prius cooling system.

 

Yep classic sign of air in the system and you may hear some gurgling under the dash too as the engine coolant flows poorly through the heat exchanger.

Try not to drive it to much as there's no dashboard engine temp and by the time the icon with the thermometer comes up the engine is way into overheat. You do not want to do that to many times with an aluminum head engine. You'll blow the head gasket.

Tricky to get all the air out. One way is to cycle the thermos as air tends to get stuck in there. That is done by bypassing the thermos relay and force the relay on thereby cycling water though it. Pull relay and bypass the switch pole by jabbing wire into appropriate pins. There's a picture on the side of the relay to tell which pins are which.

Another method is to jack the front of the car up as high as possible. Take the rad cap off and let it run and hope all the air eventually works itself out.

Put the car in inspection mode and let it run but the front must be high. Airlock like most new cars is caused by the rad being lower than the top of the engine so air bubbles tend to get stuck in the top of the engine at the cylinder head.

An airlift helps but must be used in conjunction with the thermos bypass to be effective.

 

Last night I had a similar problem, no cabin heat and engine getting too hot on the highway. It was 20 degrees out so slowing down dropped the temp until I got off the highway and pulled out the grill blocks.

I have Scanguage and was able monitor the temp and keep it below 230 after that to get where I was going. This was two hours into a trip and the cabin heat and engine temps had been fine before. I have not had any coolant system work done recently.

Could this still be air in the coolant system?

I just ran it at idle and still no heat even after the engine temp got into the 150s and the engine started cycling.

2005 Prius, 138,xxx miles.

Driving in VT and MA so heat is important. I appreciate any advice.

 

My Torque app indicates the engine coolant temp is being maintained at 190 +/- 10 in my 05. If your temp is 230, your grill block is too efficient and it's time for you to redesign it.

And if your scangauge is accurate and your temp is indeed 230 you should have a sauna in your cabin.

I'd hate to say it but your heater core might be clogged. If so, you won't get heat no matter what you do. I highly doubt that's the problem though. I have not read of a single Prius owner ever needing a new heater core.

Hope you find what the root cause is and soon - brrrrrrrrrrr. 2013/14 is the winter of our discontent!

Please provide an update when you or your mechanic finds the root cause.

 

I apologize for not being clear, the grill block has been in all winter with no problems and I use the Scangauge regularly to verify the temperature is in that 190 +/- range. It was only related to the overheating in that pulling it out dropped down the engine temp enough to make it possible to keep driving.

If it was the heater core, I'd think that the cabin would be cold but the engine would still be circulating through the radiator and not get too hot.

 

Purging all the air out of these cars is quite a challenge.
Often I request customers to stop back a few days after a fluid change so that I can re-check it for any additional air in the system.
The symptoms you relate sound pretty classic for air lock.

 

OK, now I'm really stumped. It has magically fixed itself.

I started out on my return trip from the MA coast back to VT with no heat. I was actively watching my Scanguage for the engine temperature. On small hills on the highway I saw the temp go as high as 210 at 55 so I figured I'd be OK until I got to the bigger hills further inland. I had driven 7 miles city and then about 7 miles highway and all of a sudden the temperature dropped down into the 180's. I turned on the heat and it was working.

I'll be keeping an eye on things and provide updates on any changes.

 

Sometimes the right combination of hills, valleys, left turns, and right turns, can help an air bubble work its way out.

It doesn't mean there isn't another air bubble that might peculate up, but at least you have heat for now.
continue to keep and eye on things just in case.

 

I had same problem with my car. Please follow this Red triangle & P1116 | Page 2 | PriusChat

 

You might be making a REALLY expensive mistake here.

If you have a coolant leak, temperatures at parts of the engine away from the sensor might
be a LOT higher and engine damage might result.

But the fact that it "seemed" to fix itself would tend to indicate a thermostat stuck shut......that finally decided to open up.

At the very least, when this started you should have let it cool off and then checked the coolant level in the actual radiator (not the overflow bottle).

And this kind of points out a drawback to grill blocking. If you do develop a cooling system
problem, the engine temps can spike into the damage zone before the idiot light comes on.