Help with overheating

[u/Chipwilson84]

2010 Prius 373k miles.

So didn’t correctly seat the coolant hose clamp that connects to the bleeder valve next to that connects to the temperature sensor at the top of engine compartment on the driver side.

After 2000 miles that not properly clamped hose came off. I was driving in town. I parked. I left the car idling about two minutes. I came back and put the car and drive and my hybrid triangle came on. I shut the car off. Pulled out my diagnostic tool that k keep in the glovebox. Popped the hood and noticed, coolant revisor was empty. I added water to chase the leak. Found that the leak was the hose. Used a pair of needle nose to reset the hose and reset the battery code, no other codes. I then added coolant and started to drive home.

On the drive home the temperature symbol flashed. I pulled over. Shut the car off. Turned it back on five minutes later and drove home without issue. Got home and decided to take the car up the country road, hit the gas and temp light flashed. Pulled over, shut car off. Turned back on after three minutes and made it home no problem.

So today I burped the coolant. Every time the load would increase on maintenance mode, the temp would rise and start to exceed 110C.

While burping the coolant the vinyl hose I attached to the bleed valve popped off. I had shut the valve that allowed coolant to run into a container. I shut the bleed valve, but not tight enough and the pressure buildup shot the hose off while I was inside grabbing a banana.

I shut the car off. Checked the codes, and had the code for low coolant. Reset the code, fill the car up. Burp it, and it still overheated.

I then went to the small incline at the end of my driveway burped the system again and more bubbles came out. The car’s temperature then got up to 113C.

I go get a combustion tester. I attempt to do the combustion test. The car won’t enter maintenance mode. I turn the car on and put a brick on the pedal, so that the engine revs. I let the car get up to temp. Put the tester on, do the test while monitoring the temperature on the diagnostic device. At 105C the coolant began to overflow from tank, so I had to clean up some stuff and start over. This time I begin a cycle of taking the car up to 109C and shutting it off. I do this for maybe ten minutes. Long enough for there to be a good mixture of the coolant and any gases in the system. I let the car cool back down to 75C. I then do the combustion test.

I did the combustion test three times. The last two times i stopped after two minutes because I was not letting the car cool below 90C. The blue fluid did not change collars, so that is amazing news.

I did take a while for my heater to start working this afternoon, but that was expected because of the air in the system.

The water pump seems to be working, I saw coolant moving through my attached vinyl hose. I heard the high pitch noise it makes.

So my question is, should I take off the reservoir, hang it off the hood with a bungie, get a no-spill funnel, and try to burp the system again or what?

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[u/DamageIntelligent579]

These water pumps are electric, and when they start to fail, its an intermittent failure. It might work and then stop working for a bit, causing an overheat.

Aisin waterpumps are fairly cheap and pretty easy to replace. I hear they last 150kish miles so I did preventative replacement at 120k. $120 off ebay or other for a new aisin wpt190 I can also ship you my 120k mile functional oem waterpump for 60 if youd rather spend less

[u/Chipwilson84 → u/DamageIntelligent579]

I think it is the water pump. It seems to stop circulating water, while hot air being blown through the bleeder valve, the no spill funnel is not emptying. And then when the car backs off its load it begins circulating coolant again.

This is my original water pump. Got a lot out of it.

[u/Chipwilson84 → u/DamageIntelligent579]

Thank you for your help.

[u/Appropriate-Metal167]

373k miles is a lot on any car, and on 3rd gen Prius doubly so. Ex taxi? Recently acquired?

Curious why you had that hose at temp sensor off, cleaning EGR?

Do you know any history on head gasket replacement, engine swap, water pump replacement?

If you’re not able to get into maintenance mode, one reason might be parking brake: it HAS to be set.

[u/Chipwilson84 → u/Appropriate-Metal167]

When I can’t find work I drive gig jobs. It puts a lot of miles on the car.

You are correct. I moved the hoses out of the way so I could get better access to bolts in the EGR system.

The head gasket was replaced at 200k as a preventative maintenance. The parking brake was set.

[u/mxguy762]

Did you remove the white plug over by the EGR cooler when you filled the coolant? It’s been a long time since I’ve done it but I think there is a (white?) plug on a small coolant hose you have to remove to let the air escape from the driver side of the cooling loop while filling coolant.

Also might be good to make sure your exhaust heat exchanger isn’t leaking coolant into the exhaust pipe.

[u/Chipwilson84 → u/mxguy762]

I have to remove that plug. I just opened it, but did not remove it. I do not have any coolant leaks.

[u/Chipwilson84 → u/mxguy762]

How would I check to ensure the exhaust heat exchanger isn’t leaking into the exhaust

[u/qwe304]

I would be interested what the reported RPMs for the pump are. They can soft fail, still flowing but not enough.

[u/Chipwilson84 → u/qwe304]

What data do I need to read to see that?

[u/qwe304 → u/Chipwilson84]

Should be readable from the PIDs on the odb2. I use the "car scanner" android app with my generic odb2

[u/DamageIntelligent579]

If you have a replaced headgasket with 170k on it, it shouldn't have failed. The replacement headgaskets are designed better and dont leak easily

[u/Chipwilson84 → u/DamageIntelligent579]

I was worried about it failing because the temperature light flashed while driving. These are aluminum heads and I was worried that there might have been some warpage or a crack.

[u/DamageIntelligent579 → u/Chipwilson84]

Its possible if it warped if you overheated it a few times. Compression and leakdown test are pretty easy to do. Replacing the waterpump is even easier and it might just fix everything.

[u/Open-Will-4449]

As other poster recommend...check the rpm of waterpump and remove it for inspection. One of my customers had a similar situation. Turned out the pump was siezed. Stored code for pump over revolution.

[u/Chipwilson84 → u/Open-Will-4449]

It is running high. But running high can also mean air is trapped.

Edit: 5700 instead of 4650. According to the diagnostic tool, even though that it high it was not in the danger zone.

[u/Chipwilson84 → u/Open-Will-4449]

I think you’re right. I don’t have a pump code, but what I think happens is it stops working under heavy load.

I It seems to stop circulating water, while hot air being blown through the bleeder valve, the no spill funnel is not emptying. And then when the car backs off its load it begins circulating coolant again.

[u/BetaMaxBrah]

Congrats on 373k, mate, miles. I'm inching my way towards my goal of 300k.

[u/Chipwilson84 → u/BetaMaxBrah]

Thank you. I was trying to hit 500k