I there, it looks like i have the problem with my 2009 Prius, but i was wondering : don't you need any purge of the cooling system after this work is done ? Is there any chance that some air might come into the cooling system during the "clamp" session?
Your post is missing some information. Assuming you replaced a valve or a pump and clamped coolant hoses rather than drained the system, it's impossible not to let some air into the system when you install the new part. Is the coolant level at the top of the radiator neck? There are many threads here on how to bleed the Prius system, including the need to run the CHRS pump and using the upper radiator bleed valve, or using an "air lift" system. The Prius is difficult to bleed correctly and failure to do so could lead to other problems.