Change Coolant Overflow Reservoir?

Hi Everyone,

I am wondering if I would likely need a new coolant overflow reservoir? Here is what I observed so far:

- low coolant level, all checks done when cold - level is alightly below Low line in reservoir, topped up with Toyota pink coolant and also changed the pressurized reservoir cap, then the coolant level went back to previous Low level after around 2 weeks

- had local independent shop perform cooling system check - no external leaks found, used blue dye to check for head gasket leak, dye colour did not change (no head gasket leak suspected)

- independent shop is aware to look inside the cabin near the passenger side and also underneath the car for the heat exchanger issue, no suspected leaks anywhere

- had a look myself afterwards, saw some pink coolant residue on the edges of the plastic coolant reservoir tank (see photos) - should I replace the coolant reservoir tank?

Hopefully some Prius experts would be able to share some thoughts for this unexplained coolant loss. Thanks in advance!

 

It’s for a 2018 Prius Prime

 

Thanks everyone, I had the issue checked by a mechanic - found leak in the heat exchanger. I’ll consider the bypass option since there is a nationwide shortage of parts.