Mazda 3In this video was one of the last vehicles that I serviced before leaving Mazda. Customer drove this vehicle without coolant in the engine until it would not go any further! When this vehicle finally entered the dealership on a tow truck it was cold, I added coolant and pressure test cooling system, but found no external leaks! (pressure tester is on coolant bottle as seen in video) I then removed spark plugs and cranked engine over to find this! Cylinder head was warped beyond servicing and in the end the cheapest method was to replace the motor. Lesson learned here, do not drive vehicle without coolant.