ICE coolant replacement question

The cooling fans will come on when the engine coolant temp passes a certain point. Not sure what that number is, but if you’re genuinely concerned about cooling fan functionality, there is a way to activate it using tech stream.

If you idled the vehicle in inspection mode for that long and both radiator hoses are getting hot (meaning thermostat has opened), you should be ok.

 

When I did the engine coolant change, I ran the engine in maintenance mode for close to half an hour, fans never came on, all was fine though.

 

An hour??? Wow!
Both times I did mine, I filled slowly, and just let it run at a normal start. It stopped
after about a minute. Filled the reservior and then drove it. Check it afterward and
then the next morning. I checked it after I drove it for a longer drive, and it was
at the mark. And 10,000 miles later it's still at the same mark.

 

I used the UView vacuum coolant filler. Took 15 minutes and no need for the fidgety maintenamce mode.

Since I got mine, Harbor Freight has come out with a less expensive model.

 

That's not a Prius..... And it's still easier to fill it slowly....

 

Worked on a Gen 3, which has the thermos and a nore complicated procedure.

 

Not a Gen3 Prius. That's the one people seem to have a problem with.
Again, it's still easier to fill it slowly....

 

Doggie. My Gen 3 was absolutely easy to fill with the UView.

 

rude kus, my Gen 3 was absolutely easier to fill by pouring slowly.
Both times. And it was a LOT quicker, easier, and cost nothing!

 

Gotta love you, dogman.

 

Welcome Ryan;
It looks like you did everything correctly. I would just check the coolant at every fill-up for a while - in case there's an air bubble in the system.
That's one of the things I hate about these cars; no temperature gauge. Testing the fan functionality by turning on the AC is an old-school hack. This only tells you that the fans indeed work; but on a different circuit. Hopefully someone will chime-in with the trip-point for ICE fan activation.
I've owned old Honda's; where either the electric fan or the trip-point sensor failed. Easy to troubleshoot them; because they all had temperature gauges in the instrument cluster. I do see your concern but unfortunately I don't have that answer. Sorry...

 

ewwww.... NO YOU DON'T! EWWW

 

Because the engineers are Japanese, it is easiest to remember the various programmed temperature points in Celsius, where the engineers picked easy round numbers. The engine coolant starts the fans at 95 ℃. (Or you can try to remember "203 ℉", but who has time for that?)

I can usually get the coolant up to that temperature in not terribly long in maintenance mode, by holding the go pedal partway down.

 

Thanks Chapman; Those sensors usually has a wide error margin; so if no fan activation by 205-215 degrees - I'd replace the sensor.
On my old Honda; If it didn't trip slightly beyond the midway point - definitely before the 3/4 mark; I turn-on the AC to force the fans ON. I ran the car almost a year that way; when I was in high school and couldn't afford the sensor. Luckily; I wasn't in stop-n-go traffic too often - which was the only time the car was in danger of overheating. As long as your moving; heat isn't a problem on these modern engines.

 

When you're watching the temperature over OBD, then no matter what the error margin of the sensor, the sensor reading is the value that you are seeing. So you will hear the click of the fan relays right when the displayed number goes to 95 ℃. Like it's a number programmed into an ECU or something.

Now, if you are reading temperature using some different thermometer you have inserted into the system, then yes, there is a separate question of what the error margin could be between your thermometer and the car's sensor.