Best method to drain the most coolant possible

Pulling a hose off the exhaust heat recovery system should help; it’s the low point.

there’s a link in my signature (Flushing out…) with thoughts about dealing with residual water. The basic conundrum is the Toyota Super Long Life coolant comes premixed. In a nutshell, my fix would be to look up the system’s capacity, add half that amount of (full-strength) Toyota Long Life coolant (or another, compatible full-strength coolant), then continue the fill with distilled water.

 

Was this plain tap water or distilled water?
Plain tap water has a lot of dissolved mineral in it, especially well water. Those minerals will adhere to your coolant internals; kinda like plaque clogging up your arteries. Bottom line; if your going to put water into your radiator - you should use distilled water.
I don't think you get too much snow sticking to the ground out there; so diluted coolant isn't going to destroy your engine. Best thing to do is use concentrated Toyota coolant to get the balance corrected again; then stick to the 50K mile OEM ascribed coolant changes there after. That should eventually rebalance your cooling system.

Hope this helps...

 

Discussion about alternate coolants, full-strength ones:

Zerex Asian Red vs. Toyota Long Life Red Coolant and mixing? | BobIsTheOilGuy

Just skimming a bit of page one (of three), post #13 and #16 are especially interesting.

Toyota Long Life Coolant, while maybe the best full-strength alternate, seems prohibitively expensive, and hard to find. At least on Amazon. This I believe is the part no: 002721LLAC01

Still, just across the border from me, Foothills Toyota (Burlington) has it for ~$25 USD per gallon:

Genuine Toyota Long Life Coolant

And..., from my local Canadian dealership part department: in stock, roughly $28 CDN, per US gallon (aka 3.785 liters )

Coolant spec, from third gen Owner's Manual:

"Toyota Super Long Life Coolant" or similar high quality ethylene glycol based non-silicate, non-amine, non-nitrite and non-borate coolant with long-life hybrid organic acid technology.

Engine coolant system total capacity, from Repair Manual (excerpt attached):



^ According, when refilling, I would start with 4 US quarts, then finish with distilled water.

FYI: Toyota USA sells the pre-mixed Super Long Life at 50/50, while Toyota Canada makes it 55/45 (coolant/water). Doing the math with 7.7 US quart capacity and "Canadian" mix, that'd be 7.7x.55=4.235. Doing the math with "US" mix: 7.7x.5=3.85. So 4 US quarts (the size of container it comes in) is a good compromise quantity.

 

On Australian Prius V this system may be absent. In countries where there is no snow, it is unnecessary to heat the coolant.

 

Assuming it has water from the tap, you need it out to the best of your ability. Drain and measure the amount removed.

I would buy five or six gallons of distilled water and do four drain and fills with full circulation (which means warmed up so the thermostat opens) in between.

Since each drain cycle gets 2/3 of it out each time the original tap water becomes extremely diluted for $1 a gallon distilled water times five. Add a gallon of Toyota concentrated coolant and top it off with distilled water if needed. Change coolant every 40-50 k miles from then on. It's muscle memory at that point and easy to do.

Your head gasket will appreciate it.

 

I think the "concentrated" coolant (not diluted with water), at least Toyota Long Life coolant, has half the service interval. Accordingly, I'd replace that coolant after 2.5 years or 25K miles, just the first time, and then revert to 5 years or 50K miles, assuming you carry on with Super Long Life coolant.

 

I'm 90% sure, whomever told you this is incorrect. You can get away with using tap water on old cooling systems, but on these modern cars with narrow passages and coolant control valves - they can get clogged up; rusty. If you know any steamfitter or someone who's ever managed a boiler system - they should be able to give you a good education on what happens to water and mineral deposits. Distilled water is mineral free and I don't think they pumping that through your taps.
There's a thread somewhere where a gen4 Prius coolant valve got jammed, rusted partially open. The car had over 200K miles and owner never did a coolant change. I'll adjust this thread if I can dig it up.

 

Distilled water is used to service acid batteries and it seems that it will not be difficult to buy.
The price will be less than a dollar per bottle.
You can buy a ready-made composition from a dealer and not dilute the concentrate yourself.

 

Then radiator drain is likely the lowest point, will drain the most.

Pouring in a suitable, undiluted coolant (not a 50/50 pre-mix), an amount calculated to be half the system capacity (or slightly more, say 55%), and then completing the fill with distilled water, is the only effective way to get a water-flushed system back “in balance”, at least that’s all I can think of. Several preliminary flushes with distilled water maybe be warranted, depending on your water supply.

I’d use the pre-mixed Toyota Super Long Life coolant (you have on hand) at the next coolant change, which should be in 2~3 years (shorter replacement interval recommended by Toyota).

 

The 40ppm is total dissolved solids = minerals. FWIW: our water treatment plant average is 44ppm and ranges from 26ppm-61ppm. Deminerialized or deionized water would be better for your car's cooling system
Here's the thread I was talking about. Car is Juddering / Jerking during acceleration… | PriusChat
Thread #6 img_7524.jpg; That's OEM Toyota coolant without the additional tap water mineral. Though the coolant may have turned slightly acidic due to ignoring the change interval. He had over 300K miles on it - not kilometers. As you can plainly see, you can get away with things that isn't completely "kosher", but the small cumulative effects will eventually catch up with you..

YMMV

Here in the states we mostly refer to it as distilled water vs mineral water (the stuff people drink because it's suppose to be better for them). My old facility had a boiler plant to produce heat, energy generation and supported scientific labs, where we produced our own deionized water; so it wouldn't throw off our test results. This means that everyone got a crash course on how and why we do things.......