Two years ago I replaced my 2010 motor with the 2016 motor. A month after the swap, a coolant leak ruined the water pump the engine came with. We fixed the leak or so we thought and used a new pump, well that pump actually ran dry for a small period but we fixed another leak and used that pump for about 40,000 miles till a few days ago when that one died. I put in a brand new pump about 400 miles ago and my heat was working fantastic. No leaks. I noticed the coolant reservoir was kind of full this afternoon( I check the coolant every time before and after) Before leaving the house. Took a 30 minute drive heat still works great and then my check engine light comes on. it’s the coolant pump control code, it’s totally dead and the coolant reservoir is extremely full. Getting the car towed home. is there a chance the thermostat is stuck shut or there is some kind of blockage? Prior to this after putting the new pump in I was watching the the coolant go back into the reservoir and thought maybe it was a rather weak stream but I didn’t think much of it because the heat worked great after the new pump whereas before it worked poorly.
If they thermostat is not functioning correctly it may not be allowing the coolant to flow enough. It's usually a good idea to replace it with a waterpump replacement.
What are the coolant temps looking like? OBD auto doctor app in Android is how I monitor coolant temps. Perhaps a sensor is bad?
Mine, a 2010, goes up to around 190-192 and hovers around there. When stressing the engine by going up mountain passes I've seen it goes as high as 202 or 203. It's interesting because my gen 2 before would go up to only 176 and hang around there so I guess the third gen runs a little hotter by default SM-T970 ?
Thanks for the responses. I don’t have coolant temp app. I will look towards downloading. I’m gonna swap the pump and thermostat. I can’t check any coolant temps right now because the coolant isn’t making it back into the engine it’s filling up the reservoir and never getting back out of there. Once the car is fixed I am going to sell it. Just bought a new Impreza hatch back. I loved the Prius but with gas at $4.50 it will take me 14 years of paying $1000 a year more on gas before the Prius will be more affordable than a cheaper car that gets 35mpg. I just can’t afford that right now.
Replaced the thermostat and coolant pump. Took it for a drive and had my computer with tech stream hooked up. Outside temperature was maybe 40F. Up a long hill on the highway going 65-70 mph with cruise on the coolant temps went up to like 213F but I didn’t want to get higher than that so I slowed down and the temps dropped. Most of the time on highway coolant temps were195-205F going 60-65mph. In the city 175-185F. I noticed the coolant return line to the reservoir was hot. The big fat coolant line that goes to the thermostat was cold even after driving. The fat coolant line that comes from below the EGR area and goes into the radiator was hot. the reservoir level has not dropped at all so I don’t think any bubbles have bled out. That was something unusual I noticed when the last pump failed, when the CEL for coolant pump came on I opened the hood and saw the reservoir very full, but I never got an over temp light. The reservoir has not drained and I can’t really see any coolant flowing into it when the engine is running. maybe there is a clogged radiator? Can it be unclogged? I see other people saying to in a garden hose through the radiator.
Started the car in maintenance mode and ran the car trying to squeeze the big hoses and bleed the air out from the bleeder valve. It was bleeding fine but the temps idling went up to 190 so I shut the car off and decided to try a radiator flush. Pulled the lower and upper rad hoses off. Pulled off the heater core hose and I blew into all of the hoses and got coolant to splash out from other various places. when I blew down into the reservoir drain hose the first couple times I could not get any air in. Idk if there was a bubble or what but I gave it hell and I think it cleared some type of block but im not 100%. I am able to push air and fluids through the hose now. Rinsed out the radiator with the garden hose from the upper hose, and the reservoir drain hose. I used my Chinese cable and techstream to operate the pump without the engine on and I could not only hear the pump but I could feel all the hoses swelling and little bubbles inside. I squeezed the big ones and little ones as much as possible. Bled the valve until coolant ran smooth. Filled coolant to the B line and raised it above the motor. Ran the pump a whole bunch on for 15 seconds then off for 15 seconds listening for bubbles and air. I put a water bottle underneath the bleeder to catch the bleeding coolant and inspect it, then add it back to the reservoir to keep the B line solid. i started the car in maintenance mode and this time temps went up to about 174 and drop down to 171 after that and didn’t go back above. I didn’t believe it so I let everything cool down and tried it again and it worked the temps didn’t exceed 174 again. Put everything back together for a test drive. My laptop died so I’m charging it then going for a test drive. Definitely do not have high hopes but there has been a change in testing so maybe the drive will pass too. test drive, temps were 190-221 on the highway. When it went high like that I let off, that was from stop to 65 full acceleration. But it would get up there like 217 when I floored it for sustained time to accelerate on the highway. I was in cruise control going 70. It held around 205. It would always cool down when I let off. Also the coolant reservoir was not overfilling this time. I think the car is working. I noticed that radiator was kind of clogged with bugs and debris…. Maybe she’s running hot but I have seen the coolant light come on before and it didn’t come on for the test drive. Anyone know what temp that light comes on?
