I have a 2006 Kia Picanto Ex (Automatic). A few weeks ago the car overheated, and the engine shut off. I got it serviced, and the water pump had packed up, and some belts needed to be replaced. After this the car ran fine for about a week before it started overheating again, though this time I was still able to drive, and the warning light would go off after the car was idle for about ~5 minutes. I decided to take it into the Kia service centre, and they are telling me that they bled the cooling system, but there's still some bubbles, which might mean that the head gasket needs replacement. They are asking for a small fortune to take the head off and send it away. How much would it reasonably cost to inspect and possibly replace a head gasket ?