Q: Knocking noise from radiator and coolant coming out of overflow hose

Be sure not to drive the car if it is overheating because overheating can warp the cylinder head and/or engine block causing costly damage. The most common causes of overheating include low coolant level (including that due to sudden large leaks), a faulty thermostat, a plugged radiator, a faulty radiator pressure cap, collapsed hoses, non functioning cooling fans, and a faulty water pump or drive belt. Certain engine faults, such as a leaking head gasket or poor engine running condition can also cause overheating. If you desire that this problem be diagnosed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an engine overheating diagnostic and the responding certified mechanic will get this resolved for you promptly. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.