More likely down the coolant tube where the stat sits, can't see how it would work itself into the cambelt area that's sealed to prevent road dirt getting in there. Unless you removed that cover for any reason?
I have no experience of V6 cambelt change, not sure if the water pump can be removed on its own? I know its aux belt driven, but have a feeling the cam belt has to come off Could be wrong though
The bag pipes off, plenum (if extended version), auxiliary belt
after undoing the bolts on the water pump pulley and torx bolts on the power steering pump, remove auxiliary tensioner, remove cable tray and then cam belt cover.
Can be done with cambelt cover in place but if the pump is stuck then you`ll probably damage the cover when trying to release the pump. If done with cover in place,
dont drop any bolts