Need help! Gas engine overheating. Cannot resolve.

How would I do this?

 

I replaced it myself. It is a brand new AISIN water pump. I connected and tested it before installing it to make sure it was working. It spun up very well. I can also feel and hear the vibration from the pump when it's running.

My guess also is if the water pump wouldnt be working, the car would overheat at lot sooner and at idle as well.

And if the pump is faulty, you usually get an engine code as well.

 

So I tried Mendel's advice. I ended up removing the coolant temp sensor itself instead of the smaller upper hoses (the clamps on the hoses were extremely hard to reach and I was able to remove the temp sensor without removing any other parts). A little bit of coolant leaked out. I spent about 1/2 hr squeezing all the coolant hoses with the coolant reservoir cap off and coolant temp sensor removed (highest point in cooling system).

I added a tad more coolant. Not sure if actual air escaped or just some coolant leaked out when I removed the sensor and squeezed the hoses.

Drove the car up a few hills around my house at high speeds and I couldnt get the temp to go over 194F. It is very hard to recreate this issue unless you live by some mountains, which I dont.

When the coolant was at 194F, I pulled over and felt all the hoses coming from the radiator. The incoming thick hose from the engine (driver side) was really hot. The outgoing thick hose on passenger side was slightly warm (but much cooler, maybe slightly over ambient outside temp which was 60F) than the incoming hose. The other 2 smaller hoses were warm as well. It seems like the radiator is doing its job?

I will take the car to work tomorrow (1hr drive over many hills across 5 different highways). Thats usually where it kept overheating in the past.

I couldn't check the fan speeds because its almost impossible to hook up 12V to them when they are installed in place. I'd have to remove the fans which I didnt have time for today.

Any other ideas would still be appreciated.

Ill keep you posted with my drive tomorrow.

 

Gents, thank you all for all your help.

I drove to work and back (2hr drive all highway) and in the spots where my coolant temp used to spike to 235F, it now will not go over 192F no matter how hard I try. It stays steady at 190F the whole way and as soon as it rises to 192F, theres a sudden temp drop right back down to 187F. I also took it to a very, very steep hill after all the highway driving and floored the gas pedal and got the same positive result, never over 192F and immediate drop back to 187F, then stabilize again at 190F.

Im fairly confident the issue is fixed.

Big shout out to Mendel Leisk about giving me the idea of removing the small upper hoses which led me to remove the coolant temp sensor.

So to summarize, I had a faulty water pump (but spent tons of time and money chasing other parts) and then I had some air bubbles in my cooling system that prevented the coolant from circulating properly.

The key take away is if when you're refilling coolant, remove the coolant temperature sensor (highest point in the cooling system) and remove the radiator cap before bleeding the system. This opens up escape ways for air to leave the system from both sides of the engine at the same time.

I also liked Joele3's idea to unscrew the coolant reservoir and prop it up higher as well.

Thanks to all who contributed. I hope I never see the engine overtemp light on my dash ever again!

 

Yes. My Prius still has that weird 4 way plastic connector up there. 2 of the ports are used for water flow through it into the passenger cabin, 3rd port the coolant temperature sensor screws into, and the 4th port that sticks up is nothing but a sealed plastic pipe thats useless.

I took that 4 way contraption out before because I thought I lost the white bleed screw cap (the screw cap is missing on mine but I saw it online in pics on other models).Turns out it is a plastic pipe thats sealed at the bottom. Nothing there. No hole, no valve, nothing.

Bizarre design by Toyota.

 

Sketch-1554360842471 by Sergey K posted Apr 4, 2019 at 12:09 AM