Replace All cooling system coolant

For G3, I believe the engine coolant system capacity is 7.3 liters (7.7 US qts, 6.4 lmp. qts). The correct coolant is Toyota Super Long Life Coolant (SLLC) which has a pink color and is premixed with distilled water.

The vehicle has a radiator drain plug and engine block drain plug. You need to find and open both of those to do a complete job of draining the coolant.

You also need to find the air release valve which is in the plumbing to the cabin heater, when refilling the system.

 

100k miles maintenance | PriusChat

You may only need to do the engine loop, but there is something to be said for having them in sync with each other.

 

Don't forget to drain the heat exchanger down on the exhaust under the cabin.

 

There's two @NutzAboutBolts videos linked in post #3, the one on engine coolant change in particular is invaluable.

Since you have what amounts to "contamination", having added so much water, post #4 is also a good idea. It is likely THE low point in the system. Basically follow the exhaust pipe, somewhere (just downstream of the CAT?) is the location where coolant line connects to exhaust system.

Also, consider opening the engine block drain bolt: though I've heard precious little drains from it? It's funny, on all our previous Hondas, the engine block bolt was the motherlode: remove that and be prepared for deluge.

It is hard to reach, you're likely best option is to remove the wipers and windshield cowl, and even then you'll need mirrors and braille to get to it, around the exhaust side. I believe it has a spigot similar to radiator drain bolt? I've "touched" it with cowl off, and seen a fuzzy shaky view of it with a mirror. Access is terrible. It's up high on the passenger side, at the back.

For cowl removal, watch @NutzAboutBolts spark plug change video, pinned at top of 3rd gen maintenance forum.

 

Meh, I'd just change the coolant 5k miles sooner than to mess with the engine block drain bolt.

Is there a petcock or plug on the heat exchanger?

Pixel XL ?

 

AFAIK you just pull off a hose. It's not mentioned in the repair manual, but I'm sure you'd get more out doing that. What with substantial water addition, you want as complete a drain as possible.

Would be nice if you could get 100% coolant. Then you could get away with a regular drain, maybe check the percent of the drain, do some math.

Actually that would be a good first step regardless, see what percent it's at first.

Also fwiw, in Canada the dealerships sell 55%.

 

Anybody know of an antifreeze tester that just shows percent, as opposed to freeze protection temperature? Or do you just throw-in-the-towel: reverse-engineer from the temperatures? Maybe the temperature of the coolant matters too?

 

I think the last time I wrestled with this what I did was, starting with 100% anitifreeze:

1. Mixed 60%, 50% and 40% samples.
2. Let them stabilize to practical room temperature. (Note this temp, use it with any future checks.)
3. Measured each with one of those temperature-calibrated hydrometers, and carefully mark with a black felt-tip, where the needle ended up with each percent.

Bit of a pain but it worked.

The fly in the ointment though: I guess it's impossible to do this with Toyota antifreeze, which only comes premixed. The best you can do with the US 50% mix would be do steps 1 through 3 for 50% and 40%. No way to do 60%.

 

Yes. Many of the hinged--pointer type do that, including my old Prestone one.

 

Addendum: I should've said they show percentages as well as temperatures. Coarse graduations, tho.