Inverter coolant breather valve super tight?

I need to bleed my inverter coolant after replacing the pump and an essential step is opening the "breather valve" - in quotes because I don't know the official name of it, pic below.
Looks like there are two places to loosen and I am not sure which - is it the Green Circle or Red Circle in my picture.
I tried using gentle to a little more force on the upper nut, and its not budging
... and there never was a rubber gasket on top either.

Spray some liquid Wrench on it?

Should I just replace it? I see one bolt holding this in place against the inverter.
What's the official name or even a product ID number?
2005 Prius
thanks in advance!

 

Thanks, I'll try that with a wrench's support on the bottom half.
I was very surprised how tight this was! I was under the impression that it would be a little bit more than hand tight... No clue what previous owner did. There is dirt on valve top, I'll shop vac that out.

 

uhhh, bleeding the system is apart of the process. There are allot of bubbles. Those air pockets are probably killing your pump.
This is my first purchase - and its Toyota genuine part - hopefully for atleast another 100k.

I did splash a bit of coolant in the new pump before hooking up the hoses from the old pump.

Then today, I just finished bleeding it and I don't see any bubbles in the clear tubing after a short amount of time - even tweaking the breather valve tighter and looser to confirm while the car was running.

Confirmed I am at full level, maybe added a few ounces and even did the bleed again since its easy.
techstreamed it after clearing the ECU by unplugging the accessory battery. No codes... went for a drive, just came back - no codes. Turned it off and on a few times and also checked the accessory battery's charge levels. All nominal.

The only worrisome part of this whole bleeding thing was the original tightness of the 10mm nut... it was a bit ridiculous. Its at a normal level, and I don't see any leaks.

I'm leaving the front black uhhh, cowling or whatever black plastic crap to confirm over the next day or two no leaks.
I did make a few splashes removing the clear hose from the process.
Hopefully no error codes appear.

I'm recharging the laptop so I can get out there and reconfirm no serious codes.
I dont give a flying burrito about the solar gauge for the auto A/C.

 

I have no codes but the B1421. I still show P0A80 as pending... but I have driven the car for 15 to 30 minutes twice, and checked techstream again a minute ago. I am hoping this P0A80 will disappear.

I have no idea if a battery block value of 15.4V for 1-15 on each is good or a sign of death is near.

If it helps the MAX Block Vol was 15.5 and the minimum is 15.11 some website is claiming this is around 60% acceptable Proficiency - I have no idea if his data analysis makes sense.

 

I am looking at some pics of the multiple times I used techstream and yes I do see a snowflake for P0A80, and P3000. But have since cleared the ECU, and drove the car a few times and nothing to report with a snowflake, just Pending DTC - P0A80. Im going to try and monitor the Volts under hard acceleration, etc. Which is how I drove the car earlier today to try and produce a red triangle - but it did not happen. Im averaging around 15 Volts for Blocks 1-15 as mentioned earlier.

I told my girl - since its her car - she has to drive it, till it happens. Theres pretty much no other way. I think. All the data I see is that its just typical time is not on your side, its going to happen. The car never was in "limp mode". She drove it home the first time the Red triangle appeared at least 30+ miles home.

 

Thanks.
When I say my girl... I mean my wife. She drove it downtown today with no issue. I'll just continue to monitor the battery power. I'm going to stress test it with full blast a/c, stereo, and driving like it's a BMW or Nissan Altima.

 

I cleared the ecu by disconnecting the accessory battery...I don't know how to clear it via tech stream.
Last check I did last night:
But I think yea it was still in there as pending, even after 3 trips. The check engine light definitely showed up because I didn't bleed the new pump install.

After doing that, it seems like smooth sailing for now. Again, no idea if the volt numbers are good, failing slow or fast...

I can't read that monitor in the car - the colors are crap and screen burned.

So purple, green, white, blue are useless. I see solid block bars not all of them...so it has a charge maintained. I see arrows moving around.
I will say this...that at startup when the mechanical engine starts...and then stops...it's a long time before it starts up again...could be due to weather temp....this is at idol in park, farting around in the car.

Writing from cellphone...meh.

 

I do not know, its not that far off - car went bad - red triangle - error codes about pump, etc. - fixed the pump incompletely - drove car - seemed ok - then it wasn't shortly after a few trips - 2 drives - check engine light came back - bleed the coolant properly - cleared ECU, drove the car multiple times and no issue.

ECU is doing what its suppose to holding that error code as pending until its deemed ok after multiple trips.
Not much else I can do but, monitor for codes, and any noticeable downgrades in performance.

 

I tackled this with the scientific method - make a hypothesis, and test, gather results, test again... its like fixing any computer problem more or less. I just rechecked with Techstream after the car was driven to and from for about 50 miles total. I have no codes to report other than the solar a/c panel one - that I dont care about. The battery went up in voltage from 15 to 16, while idolling the switching off and on of the gas engine was faster too, compared to before. The P0A80 code is gone, no longer pending. Many of the important subsystems had zero error codes to report. The Prius is fine.

 

Long story short: the error codes came back...for the hybrid battery. I have the freeze frames of what upset the system. I will probably start a new thread regarding this.

But for two days, it did seem resolved.
Another issue I have with this car is the oil dipstick - everytime I check it ..there is a very long stream on one end going up the guage ...but a semi clear and defined horizontal line that should be the actual Measurement - this line is annoying to read...I should post a pic shortly.
Battery Voltage is around 13. The average commute for this vehicle is around 45 miles daily.