Replacing spark plugs

Where exactly is this vent on a 2012?

 

It was here:

wider view:



Close up:



In later model years, the main component is still there, and the same hoses connect, but the white cap is gone, which you could turn to allow air or coolant to flow through the spigot on the side.

 

Thanks for sharing the pictures @Mendel Leisk.

 

Yes, if your car has that valve and you want to use it, you can, and it will behave as described.

Toyota later decided there was no need for it, or any of that related business in the instructions, and the later gen 3s still can be filled with coolant.

 

I have never done anything on my 12v's coolant drain and fills other than leaving the reservoir cap loose during the initial warmup.

Trapped air is not a problem unless combustion gasses are entering the pressurized system.

 

Yes.
It was already "gone" by the time they made my [late-year] 2011, so would likely be missing from a 2012.

 

You can also leave a gen 3's reservoir cap closed during the initial warmup, like the repair manual says to. There is enough headspace in the degas bottle to receive the air that circulates back.

I'm not sure why they went out of their way to say put the cap on, but one guess could be that when you let the system reach pressure, any bubbles are half as big, and maybe circulate back to the bottle more easily.

 

Last fall I did engine coolant replacement (and inverter coolant), folllowed the repair manual instruction to fill reservoir to “B” line, cap reinstalled, run in maintenance mode. Worked well, coolant dropped, to slightly above full line IIRC.

One thing, after running engine for about 20 minutes I figured it was done. Topside hoses felt hot. I had the front raised and engine under panel removed, so shut off the car and went under to replace under panel, felt a couple of hoses under there, and unlike the (toasty) topside ones, they were still stone-cold.

accordingly, I restarted car in maintenance mode, crawled back under, and just lay there, reflecting on life an such, occasionally checking on the hose temps. Eventually they started warming, presumably due to thermostat opening, and got hot quite quick, in just a few minutes.

Then I dubbed it done.

 

I assume this was only on the ICE side, since there is no thermostat on the inverter side.

 

is this your one-and-only Prius? If so, maybe fix your avatar. In North America, should be model year 2010~2015:

 

If you get some MAP sensor cleaner and spray it well, it might take care of that issue.
But check the wiring....