Hello, I just changed my 2017 Prius’ hybrid inverter and engine coolant. In the engine coolant, there is a portion(see the attached photos & look for the cicrled area) it is empty. Although the coolant is on full mark, that small area is empty. Is it normal or should I open that tuny plug and fill it up? Thank you! 4E7CC5AE-DDCC-428C-AC6C-84A9C36514CB by Shujayet posted Aug 7, 2022 at 8:11 PM
It is the same for the coolant overflow tank for the radiator. I think it is normal. As long as it still reads in between low and full, you'll be fine.
Okay. Thank you. It reads a bit higher than FULL for both the engine and hybrid system coolant tanks.
Need to read between low and full (high). There needs to be room in the tank for expansion of the fluid when it heats up.
Because when the fluid shrinks after cooling, you would have less in the reservoir if they didn’t have the expansion area inside the sealed tank. And because that’s how they manufactured it, I guess.
Just leave it. I will be fine. It will either be expelled via the overflow or you'll just have extra. Won't hurt anything.
