Question: how do you know if you need to replace your radiator?
Answer: There Could be a Leak. One common sign a radiator is going bad is if it is leaking coolant, which can be caused by a crack. ... 
There Could be Rust. ... 
Overheating is a Sign of Radiator Problems. ... 
A Thermostat Goes Bad. ... 
Air is Present in the Cooling System. ... 
The Water Pump Fails. ... 
An Obstruction in the Cooling System.