My Gen 2 prius has 420k miles on her, been great, recently had the error code to replace the inverter pump so I did with OEM pump. My problem now is that It loses cabin heat, overheats, red triangle lights, gets air back in system (you can hear inverter pump running dry), overfills the coolant overflow box. I have to blead all the air back out and its good but then overheats and repeats the issue. I replaced the thermostat but no change. I dont see any leaking around belt driven water pump.
Sorry, a bit confused here. Which coolant bottle is over flowing and boiling out? Do you have OBD codes and what are they? Cabin heat is driven by the engine coolant pump, Has that and the thermostat been replaced? Check status of spark plugs and top of piston for signs of steam cleaning. Check under your radiator cap, for coolant - lack thereof will prevent your car from transferring coolant between your reserve bottle, into and out of your cooling system. You've also have a bleed valve on top your engine somewhere, near your valve cover. Hope this helps......
Although cabin heat uses the engine coolant loop, isn't the actual flow to the cabin heater controlled by an electric pump by the brake actuator? Sounds like the OP has some confusion about the coolant systems. The inverter cooling pump is located behind the driver headlight and circulates coolant through the drivetrain electronics. The engine coolant loop flow is created by the belt driven water pump mounted to the passenger side of the engine. This loop includes the coolant control valve and heat storage tank/pump system. It also supplies hot coolant for the cabin via the previously mentioned electric pump. I'm sure there's some good diagrams somewhere on the forum.
You can reduce confusion by reading the Gen2 Maintenance manual. If you send me a PM stating the year of your Prius, I will reply with a link to the correct maintenance manual (I have two: One for 2004-2005, and the other for 2006-2009). JeffD
the radiator overflow bottle gets filled up and then air is in the system. No error codes. Thermostat replaced
yes its the engine coolant loop that is not flowing properly. Once I bleed all the air out it then overheats and fills up the radiator overflow bottle and puts air back in the system causing the cabin heat to not work.
Are you speaking of the 3 way valve behind drivers headlight. That was just replaced and when I manually activate it from the fuse block it runs and I can see coolant circulating pushing up air bubbles in my funnel to radiator.
Best way to get air out of that system is to take off the plastic cover in the engine compartment and take off the actual radiator cap and top it off when engine is cold before you start driving everyday. Not sure what method you're using to bleed air from engine coolant loop but its not right method and is not working. Try method above instead. But make sure you never ever try to take radiator cap off when engine is hot.
I'd go after the water pump & thermostat first, with that kind of miles. If the water pump isn't moving enough coolant, it'll boil out. Ditto if the thermostat doesn't open up. Start monitoring ECT, so you don't blow your engine. Also check if the electronic radiator fans are working, toggle them ON. Worry about the cabin heat later, if you blow the engine, you'll be walking anyways.... Once the engine is running properly again, well tackle the cabin heat issue.
Fans are working. I have been bleeding it by first manually activating the inverter 3 way pump with a funnel up top filled. After all the air I can get is out, also squeezing upper radiator hose, I then start the car and turn heat on MAX and continue squeezing top hose. I just finished that process again and put a new radiator cap on
I did thermostat the other day, Pump was on my list next. Fans are coming on and off, just went through the bleeding air process and confirmed. TY
Well I changed water pump yesterday and it did the same thing, over heated, through code P1150, pushed all the coolant into overflow which overflowed and put air in the system. She is at my service guys shop to test for coolant leaks and engine leaks.
