Another coolant/heating problem, this is different...

Hey guys,
2009 Prius I purchased in November 2018, that decided to not have any warm air in the cabin and overheat this last January. I parked it and am just getting to the repairs now.

I took the system apart, and found a number of things wrong:
1. The belt was on the wrong side of the water pump.
2. The thermostat was bad (didn't open at or above temp when boiled on stove).
3. The radiator was not flowing well.
4. The heater core was flowing fine.

So I replaced the thermostat and radiator, flushed the system and started the process of bleeding the coolant should be almost complete. Radiator is now flowing very well and the new thermostat opens at 180 as it should.

When the ICE is running, the heater is now blowing very hot air. However, when the ICE stops, the air becomes cold. I have the climate on Max temperature and the blower fan on high.

The auxiliary pump is running and seems to struggle when I pinch the line but could that be bad?

I noticed that the drivers side of the radiator hose is hot, and the passenger side is cool. Could just be the efficiency of the new radiator?

I am going to keep looking at the bleeding process, but since the air gets hot when the ICE is running, I figure this shouldn't cause a problem when it stops.

Any ideas?

Thank you

 

Started with the thermostat and water pump, disconnected the top radiator hose, found the radiator restricted, so I removed all hoses, flushed the system. Pretty standard for those that work on water cooled engines.

PN 1629021011 Toyota lists this part as "Auxiliary Coolant pump"

Between the Master brake cylinder and the ABS brake proportioning/actuating valve. Behind and just below the inverter. There are 4 pumps in the system: one mechanical, three electric.

Between the 1629021011 pump and heater core. Comes from the passenger facing output of the pump.

While I take some umbrage at the insinuation of ignorance, you don't know me and it is reasonable. Yes, I found it very helpful when I purchased of our first Gen 2 Prius.

The person before was having a loss of radiator fluid. They thought it was a cylinder head gasket. It turned out to be a bad radiator cap that was causing the fluid to leak by the valve assembly. Replaced the hose, clamps and cap. My assumption is that they tried to use the radiator stop leak and plugged the system because the radiator was not flowing.

Yes, there are two, but I would classify them as ICE versus Electric as the second loop not only cools the Inverter but also the electric winding in the trans-axle. I also used all three bleeder valves to remove the air from the system. Most people only know of two.

Yes. But just because there are four pumps does not mean that the heating of cabin requires four pumps. There are only two pumps involved in cabin heat. The mechanical runs during ICE operation. If heat is called for the by ECU, in the cabin, the auxiliary pump keeps the circulation going as I stated before.

No DTC's recently or I would have reported these but good call as I should have mentioned it. Techstream gives it a clean bill of health for now. The pump IS running as I stated before. I can hear it running, I have isolated the running noise to that pump, and when the hose is pinched, the pump goes faster (cavitation). My guess is that since the current draw of the motor is not high or low, this wouldn't trigger. The pump did flow water, but I never pressure tested it due to the lack of DTCs around it. There were DTCs back in Jan, but they were cleared by the 12v battery's loss of power after 3 weeks in my barn.

Just to include another point. The valve is working and hoses are connected correctly. The heat storage system is working well on this car and not part of the problem.

The auxiliary pump is north of $100 so I wanted to run this by the group to see if there is anything I missed. If you have ever worked around the inverter, you know that removing the inverter and changing this pump will involve the bleeding cycle AGAIN. Any Prius mechanic will tell you that to avoid that AGAIN is worth the check. I am lazy enough to just swing the inverter instead of removing the electrical coolant loop, but still, the ICE is the real problem with the air in the system.

We have three Prius in the family and one hybrid Camry. Prius are all gen 2.

So, just to ask again. Should I bite the bullet and swap that pump or is there something else I may have missed?