Coolant light on...not sure why

you probably need to bleed the air out. i'd dump the mech

 

Your regular mechanic didn't do the job correctly... Take it back to them! There's two separate cooling systems in the same radiator. The inverter cooling system which is where ( "air in the coolant thingy is" ) aka: the system needs to be purged of air.

The other part of the radiator is coolant for the gas-powered engine, which is where the valve is...

Because mechanic is unclear on this you need to take it back and tell them to figure it out.

 

One possibility, check the mechanical water pump or belt.
When the gas engine is running the electric water pump shuts off.
When the gas engine stops running the electric pump kicks in.

Had my car toss a belt this year..
Got red triangle.. and car got a bit warm. I was watching it on Hybrid Assistant.
Once I pulled over the gas engine shut off by itself as normal.. and the temps returned to normal..

Also possible some junk from the valve got stuck in the I take of what electric pump.. that happened to a friend of mine.. but that won't cause an over heat situation.. just loss of heat in the cabin. If that pump fails will cause a code.

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I agree then I bet some air bubble in the system. They can be a bit if a pain to bleed the engine coolant side.

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tbh, i'm not qualified to answer that. if the air is causing overheating, you could blow the engine.

hopefully, someone with more knowledge will step in with an answer. unfortunately, it's pretty quiet around here due to the holiday.
@PriusCamper or @kens97uber171 might know.

 

First of all this issue has nothing to do with the inverter coolant loop so forget that and it has nothing to do with the hybrid battery so don't bother that guy. Concentrate on the engine.

There is no coolant symbol on the dash there is a icon for a thermometer with wavy lines under it .
When that is launched on the dash it means the engine is overheating. That symbol is very very bad and if continued driving on it will then launch the red triangle of death meaning the engine is in severe overheat. Usually that will damage the aluminum cylinder head. I would not drive the car till this is sorted out.

So not sure why your saying its not overheating because it is and you will never know how bad unless you hook a scan gauge to the car and it will tell you the engine temps. There is no engine temp gauge on the dash.

If air is trapped in the coolant loop it gets trapped in 2 places one is the classic top of the engine in the cylinder head because like alot of modern cars the cylinder head is above the rad and air bubbles flow to the top of the coolant loop. The top is the engine head.

The other place is a Prius oddity the coolant heat recovery bottle called the CHRS. Coolant heat recovery system. That thermos bottle is located below the drivers side headlight. It has a pump that circulates the coolant when the car is first started. Air will get trapped in there as well. Here's a pic.

Hot Engine coolant is stored in this CHRS thermos bottle after the car is shut off so when you start the car in the morning the 3 way coolant valve switches over to allow the coolant stored in that thermos bottle to flow into the engine so the engine will warm up faster. When the engine reaches proper temp then that 3 way valve switches over to the normal engine radiator. Its strictly for emissions as a cold engine has very bad emissions.The quicker you can warm up the engine the better the emissions. Low emissions is the most important mission of a Prius but it requires a somewhat complicated system. You should see a schematic for its fuel vapor recovery system for the gas refueling. Wow.

So clearly the knucklehead that installed the 3 way valve left the cap off the rad. He's terrible at this and I highly doubt he bled the air out which is complicated as you have to cycle the CHRS bottle to get the trapped air out. There's also a hex key bleed valve on the radiator itself.

The fact that he poo poo'ed it and sent you to an auto parts store for parts is ridiculous so stop using him. Also just disconnecting the plugs to the 3 way valve while repairing it will launch codes. A proper repair of that valve is to clear those codes after the repair.

There are hundreds of posts about air getting trapped in the engine and how to rectify this. Use the search forums button up top and search coolant or air trapped or overheat.

 

There's no electric water pump concerning the engine only the CHRS bottle pump which only runs momentarily. The engine only has a mechanical water pump.

 

Anyone have a preferred Prius Chat link for flushing-refilling & bleeding both the engine and inverter cooling system? I'm about to look for one today as I've decided if I'm gonna replace my inverter I might as well go after all systems related to the radiator and be thorough about it. Anyone have a preference for what kind of flushing chemical to use?

 

Flushing is not necessary unless some goober put the wrong coolant in it and its sludged up. The G2 is extremely easy on the engine coolant and very hard on the Inverter fluid.

Search for Pat Wongs post on doing the coolant change he has the info to jump out the CHRS bottle motor and turn on the bottle motor and circulate whatever air lock it has .

Personally as someone who has done a full engine /rad dump I highly regret it. Its alot of work with not a great return.

You are much better off just dumping the rad only a few times and add fresh coolant. It will not invoke an airlock and will really help.
Do that once then a few months do it again. very easy with no horrible after taste. The rad petcock is on the drivers side.

I would be way more concerned with the Inverter fluid.

 

You are incorrect.
It's the big pump that cost $300 or so. It is located near the ABS pump.
There is also a pump for the Thermo bottle.
It is located down near the Thermo bottle.

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What big pump are you talking about....the Inverter coolant pump?

There is a Water Pump Motor (AC) in that area where you are talking about but I don't know what that motor does and have never heard anyone referring to it on this site. It has something to do with the AC system as its located on the Air Conditioning schematic. Fused by 10 AMP A/C (HTR) fuse and relay AC W\P Relay.

Its back there by the 3 way.

But has nothing to do with the engine.

 

NO!

Inverter pump is always on when car is IG-ON or READY, and REMAINS ON unless the car is OFF or the inverter pump is defective.

The dangers of misinformation!

 

That "$300" pump is the heater cabin pump. Has no adverse effect on operation of gas engine, and not tied to the inverter loop. If this pump fails, you are w/o cabin heat. That's it. This pump also has a very low failure rate; few postings about it on PriusChat.

The CHRS (Coolant Heat Recovery Storage) will activate as needed, as determined by the vehicle:
1) upon making the car READY.
2) when the car is turned OFF.
When this pump fails, a CEL is triggered. Failure by this pump will not leave you stranded.

Misinformation is a terrible thing!

Now you know the difference of the pumps, what they do, and when they are activated.

 

Thanks for this... First time I realized there are four pumps related to coolant in a Prius: 1) inverter cooling pump, 2) engine coolant pump, 3) CHRS pump, and 4) Cabin heat pump.

Thanks... That's helpful...

 

I understand perfectly well what they do the gentleman is talking about an overheat situation not an inverter problem as far as I know....

The inverter pump is located underneath the driver side headlight.

and yes I know it's got a very low failure rate thank God since it's three hundred bucks.

But it is involved in the internal combustion engine coolant loop which is what the guy was asking about. It kicks on when the gas engine stops turning, and kicks off when the gas engine starts running and uses the eat mechanical water pump. I've had the car completely apart I understand how all of it works.

I changed my own ABS accumulator pump have you?
I know perfectly well what I'm doing. I think we have a misunderstanding about what the gentleman is asking about it could be that I'm incorrect about that, but I'm not incorrect about what the pump does...

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