Q&A

 Master

The way an automotive shop would locate the leak is by removing the radiator cap and attaching an adapter that screws on in place of the radiator cap. Something that looks like a bicycle pump with a pressure gauge attached to it is used to "pump up" pressure to simulate pressure generated when the cooling system is at operating temperature, the leak is then found sometimes it is obviously leaking from a coolant hose or cracked housing, failed gasket or water pump, sometimes the engines cooling system needs to be inspected from below or inspected using a mirror and flash light.
A dealership has a reputation to uphold, we tell our customers work that needs to be done that would otherwise lead to a failure and things that should be done to prolong the life of a car. Some customers want to hear what they can do to make their car last longer some don't want to hear it. Many places do "over sell" there is a balance and a shop should take the time to show and explain things properly to people to build trust.