Waterpump is in the front . Unlikely to send coolsnt to the back of engine. Should be the valley hose behind thermostat , under throttlebody under manifold.
there are also the knock sensors in the valley. They usually onLy fail trough corrosion after being immersed with coolant
manifold gsskets is not such s bad idea
Water pump could be done at the same time . Thermostat housing can get briddle over time.
i will ad some picture from my spare

 

Hello everyone, I got the car back last week and everything seems to be back to normal. Thanks to all for the helpful advice.

 

Now what has ben done to it? What was it?

 

Replaced the thermostat housing, thermostat, expansion tank, and serpentine belt, flushed and refilled with OAT coolant.

 

Check a couple of times on the level for the next couple of days. Prone to have air locked inside.