Q: Car overheated and blew out coolant

Coolant can leak from a variety of places. The system, when warm, is under pressure; 22 psi on your A4 Quattro. Even when the engine is at normal operating temperature, when a sudden leak occurs, it can “blow” everywhere. If the engine was too hot when the leak occurred, the loss of pressure could have caused the coolant to boil. Adding pressure increases the boiling point; remove the pressure, and it boils instantly. Faulty head gaskets can add even more pressure to the system.

In any case, the entire system will need to be inspected to determine what is leaking. After the leak(s) is/are repaired, the performance of the system will need tested: The radiator, thermostat, cooling fans, and water pump. Consider YourMechanic for an inspection of your overheating issue, and repair - our mechanics provide diagnostics at your home or office.