Prius Inverter and Engine Coolant Drain

Hi PriusChat,

I just changed my 2012 Prius Touring (Yes, its Canadian) today at 191,708 km. I bought 55/45 premixed coolant from the Toyota dealership. It costs me $19.99 CAD per 3.7L jug with 0.80CAD environmental fee plus tax in Toronto Canada. The inverter crush washer was not found in the database, but the dealership guy simply sold me a transmission plug washer.

I tried to take shortcuts without removing the engine undercover using photos from previous PriusChat contributors. I am a mechanic newbie, and I will try anything that will make the work easier.

Inverter Plug shortcut:
Inverter fluid change | PriusChat
Not possible as I don't have such a long 10mm hex socket. And I couldn't really see the plug through the rectangular hole. The plug was also on tight, so I needed a breaker bar. There was not enough clearance for the long breaker bar.

Radiator Spigot Shortcut:
Notes on changing the engine coolant on a gen 3 | PriusChat
This one is totally possible. I was able to reach in through the rectangular opening and touch the switch. However, I needed to remove the cover anyways as there was no inverter plug shortcut. My advice is be prepared with a short tube to redirect the coolant.

1) Undercover removal
I spent over an hour trying to remove the large engine undercover. The picture provided by Machanon's blog is accurate except I had one more clip in the middle (the 2and hole away from the one in the middle).
https://blog.machanon.net/wp-content/uploads/2018/01/diy-how-to-replace-pcv-positive-crankcase-ventilation-valve-on-3rd-gen-2010-2015-toyota-prius_03.jpg
The three clip holes in the rear are slightly larger. Two of the clips rear were different as they were long and pointy.

IMG-1486 by Siward posted Oct 5, 2022 at 5:16 PM

I had a tough time removing the clips. I used a flat head screwdriver to loosen the clip head until I could slip my harbor fright push pin tool underneath it. It definitely took me more than an hour. I guess it would have been faster if I broke some of them.
Push Pin Pliers

I gave up in the end and took a shortcut by only removing the driver's side clips and bolts. Only half of the cover is removed:

IMG-1477 by Siward posted Oct 5, 2022 at 5:16 PM

I even broke one of the bolts. I wonder if I can somehow get a screw extractor to fix this:

IMG-1475 by Siward posted Oct 5, 2022 at 5:16 PM

Coolant Plug removal
If the car is jacked up high enough, you will have enough room to reach for the inverter plug with only half of the cover off and bent down. I ended up using a 1/2" drive breaker bar (18" long) with a 10mm socket attached to a 3/8" to 1/2" converter. Give it enough leverage, and you will hear a creaking noise and it will just break loose. Make sure your 10mm hex is in there correctly before applying force as you can round it. When done, replace plug and torqued to 29ft-lb.

My inverter plug was very rusted. I should have bought a new one and replaced it. Maybe next time.

Engine Coolant via Radiator
Next was the engine coolant via the radiator spigot. This is straight forward. Reach in and turn the knob CCW. As you can see in my picture above, I used some vinyl tubing to redirect the coolant into my tub. There was left over coolant in the reservoir since the car was jacked up pretty high:

IMG-1476 by Siward posted Oct 5, 2022 at 5:16 PM

This is okay, since I am more interested in refreshing the coolant rust inhibitor properties than bleeding all the coolant. You could simply drop the car back on the ground, but I didn't bother.

Inverter Bleeding
I filled my inverter coolant above the full line about 3mm. I told my helper to quickly pour more coolant if it drops below full. My helper just stood there and did nothing. The first inverter bleed toggle drained the reservoir to empty! I hope this didn't mess up anything. I fired my helper and filled it up on full. Subsequent bleeds were done properly. The reservoir stopped dropping in coolant level after about 4 toggles. I found that you can wait until 6 beeps before turning the car off.

Engine Bleeding
I filled the engine coolant reservoir to above full to the "B" line and started maintenance mode. After idling for 10 minutes, I turned the heater to "HI" and then turned on the fan to low. After 20 minutes of idling, the coolant only dropped half way between "B" an "F". I started reving the engine by stepping the gas. I did this a few times after at the 30min mark to the 50min mark. The engine was hot. The coolant tube was hot. The radiator fan never came on.

After 50 minutes, I kicked it out maintenance mode and took it for a test drive around the block. No surprises.

 

I also changed the motor oil while the car was up. I had to take the same clips off anyways.

 

The conclusion is that that the engine coolant can be changed without removing the cover! I have verified it by reaching my hand in the rectangular opening to reach the radiator spigot lever.

Next time, I would buy one of these to see if I can remove the plastic clips easier.
https://a.co/d/e55w8jf

 

Six beeps before it goes quiet and the engine kicks on. I followed Nutzandbolts video, but I didn't want to toggle it too many times.

I have been driving the car for the last two days. I haven't rechecked coolant reservoir since.

I am guessing I had some coolant left over in the system because I drained it on jackstands. The car wasn't level when it was drained. I will try taking it on a long drive on a highway tomorrow.