Add coolant air bleeder valve to 2012 Prius?

It's not needed. Why add something that is not needed?

 

Yeah, Toyota got rid of that valve, and didn't even change the part number of that fitting. So even if you go and order the part number for the 2010, unless you find new old stock somewhere, you'll end up getting one without that valve.

They also changed the repair manual where it tells you how to fill the system, and all they changed was to get rid of any talk about that valve. They didn't add any other steps or anything extra you have to do because the valve isn't there. It all seems to point to them learning that no one was filling the cars any better with the valve there than they could without it. And, those are the instructions they write for their own techs to follow, working on the clock; if the change made it harder to do or take longer, they probably wouldn't have changed it.

 

You could pull off one of the topmost EGR hoses temporarily while filling.

I had that vent open when I replaced coolant a couple of years back; can’t recall if I could feel air coming out (when filling). Next time I should make a point to check.

 

If you have the valve and you open it while filling, you inevitably will feel air coming out.

Also, Toyota seems clearly to have concluded, after fussing with that for two years, that their coolant could be refilled just as well without doing that (and also without adding any other step to substitute for it, like pulling a hose off).

Both things can be true. They simply removed that part from the instructions, and kept the parts where you fill to B, replace the cap, warm up the engine, and watch the air switch places with the extra coolant in the degas bottle just the way they designed it to work.

 

Born to fuss