Q: I have a 08 Nissan Altima 2.5 why is it running hot?

The heater is a "heat exchanger" just like your car radiator. If the car is running hot and you blow air over the heater "core" in the passenger compartment you, in effect, increase the cooling capacity of the car’s cooling system and that reduces the temperature of the circulating engine coolant. Overheating a car engine can cause lots of costly, hard to repair damage and so if you know the car is actively overheating, best practice is to not drive it until the issue is resolved. If you are able to keep the engine temperature in the normal range by operating the heater that will work as a temporary measure. But, again, if the car is actively overheating you run a substantial risk of causing damage of various types.

The most common causes of overheating include low coolant level (including that due to 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. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.