2 Gallons coolant enough for Inverter and Engine drain & refill?

It would be pushing it. Depending on how you drained the engine coolant (radiator, water pump and/or thermostat) and for how long, the engine loop can take over 6 quarts.

The inverter takes around 2 quarts.

To be honest I have never kept track, but it’s usually around 2 gal to do both, give/take some.

I would purchase 3 gals to be safe.

 

I did both of mine with just 2 jugs a couple months ago. Had a tiny bit left over.

You can always buy a third and take it back if you don't use it

 

Buy from a local dealership parts department, and check with them while there: could you return the third with unbroken seal.

How much you're going to need may vary, depending on how thoroughly you drain. On the engine circuit, some people have just drained the radiator.

There is also a drain on the back of the engine block, hard to see and reach; not sure how much you'd get from there. I know on Hondas it was biblical flood, but a few people have told me here they got hardly any, on 3rd gen Prius. I've not done either yet, think it's next fall it's due for me, due to months.

Someone else mentioned they disconnected a hose on the exhaust coolant heater, got a goodly amount there.

 

Take a look at the attachments I posted. For the engine it says to drain the engine block too, and says "standard capacity" refill 7.7 quarts. Not sure what "standard capacity" is, suspect it would be with a near-complete drain. I would try to drain as much as possible, why not.

 

To even see the engine drain bolt is tricky.

If you take off the stamped metal underplate, just aft of the engine underpanel, you can spot it, and probably reach it with a wrench to loosen. If I recall correctly it's has a spigot, the intention being to push a tube onto it, then unscrew it a little with a box wrench, and the coolant drains in an orderly fashion through the tube.

Far cry from my Hondas: put on rain slicker, remove large (and stubborn) bolt, prepare for deluge...

 

One thing to do is measure how much you pull out, then replace the same amount.

I had 2 gallons and it worked fine by using the petcock on the radiator and the drain bolt for the inverter .

But buying another gallon never hurts as long as you can return it if unopened.

 

The radiator petcock od is about 11/32", if you're shopping for tubing. Not sure about the engine block one, wouldn't count on it being the same, maybe smaller. Maybe a little flexi surgical rubber tubing section at the end of your drain tube, one size fits all.

With the radiator you could really just let it rip into a drain pan, but the engine block drain is up high, a bit messier without a tube.

Again, with Hondas in the past, remove the engine block coolant bolt, and stand back, lol.

 

This is the tutorial I used (inverter, engine coolant, transmission fluid, and PCV valve)... while I was down there, I changed the oil as well.

DIY: How to Exchange the Inverter Coolant On Your 3rd Gen Prius » Balancing Act

about 1/2 way through the inverter tutorial there are links for the engine coolant, transmission fluid and PCV valve tutorials.

NOTE: My inverter 10mm hex bolt was very rusty and difficult to fit a tool in. I bought another one from the dealer for $5 as well as a bag of washers (needed them for the transmission fluid bolts as well --- same bolt).

 

Good link, thanks for that. Just a couple comments on it.



In the above pic, I have those chocks, and the sawtooth face (flagged with arrow) I'm pretty sure should be on the floor, and the face on the floor (it has a slight concave curve) should be against the tire. Also, chocks are not very effective unless you have them on both sides of the wheel (as sketched in). Firmly tap them into place too.

Basically you want to have four of those, one on each side of the tires at the end that stays on the floor. Push them in firmly, and maybe even tap them with a small sledge hammer or wood block, what have you.



In the above pic, the red circles for plastic fasteners, there's actually two sizes of fasteners. Towards the rear there are a couple that are larger, and have grey heads. Going from memory, I believe they're the ones I've flagged (with arrows). Also, if some need replacement, I would highly recommend to get the proper Toyota parts (see attachment). They're the right size, will last pretty much forever, IF you wash them out with soapy water with every removal.

I'd recommend to remove that whole panel for every oil change. Also put a drop of oil on each of the bolts, brush it around with an old toothbrush. Be careful when installing oiled bolts, it's easy to snap the heads off with impacts, or even a ratchet wrench, if you don't take it easy.

 

Does anyone drain the exhaust heat recovery branch of the engine cooling system? It accounts for 0.7 quarts of the total 7.6 quarts, according to my manual.

 

@The Critic did.

Would he do it again?