Is your car overheating then going back to normal? Then you likely have a bad thermostat or a bad radiator fan.
Overheating is serious shit. If your car overheats, it can blow a head gasket or even crack the engine block!
That said, anything that has to do with overheating needs to be attended to as soon as possible.
Before we get into the specifics of your car overheating and going back to normal, I want to be very clear about what this means.
What it means:
You are driving along and you notice your heat gauge getting very high. And maybe you receive an overheating alert on your car’s dashboard or infotainment system. You start to panic, but all of a sudden, the light goes off and the temperature gauge returns to normal. Your problem is gone and all is well in the world! Yay! (Don’t get too excited)
What it DOES NOT mean:
Your car overheats. So you turn it off and the car naturally cools off because it’s not running.
This article is about your car overheating then going back to normal WHILE IT IS RUNNING.
Why is my car overheating and going back to normal?
School time. Let’s begin by talking about how your engine keeps cool.
When your engine runs, it gets hot. Very hot.
Coolant (aka antifreeze) flows around inside your engine and keeps it cool.
When you first start your car, the engine is cold and the coolant just flows around and doesn’t have much cooling to do. Your car is in the process of warming up and getting to its proper operating temperature.
As you drive more, the engine gets hotter and eventually needs to be cooled.
Once your coolant gets hot, it can’t keep your engine cool, so your coolant needs to be cooled.
Sorry if that’s a little confusing…. Stay with me!
Enter the thermostat.
What does a thermostat do?
When your coolant gets too hot, your thermostat opens and allows the coolant to flow through your car’s radiator. The radiator removes heat from the coolant. The cool coolant is then sent back into the engine to cool the engine. When the coolant leaves the engine, it is very hot and is sent through the radiator to cool off again.
Rinse and repeat. You get the idea.
Your coolant basically helps remove heat from the engine. It absorbs heat from the engine, expels the heat through the radiator, and re-enters the engine to remove heat again.
If you’re a visual person and would like to see how your car’s cooling system works, this animation is pretty awesome….
How a bad thermostat causes car overheating then going back to normal
It varies from car to car, but most thermostats will open when coolant temperature reaches around 185 degrees F.
If your thermostat doesn’t open at the proper time, coolant won’t be able to enter the radiator and get cool. So hot coolant will flow around inside of the engine and cause it to overheat.
When your bad thermostat finally decides to open, your car’s temperature will regulate and your temperature gauge will go down and your warning lights will go off.
All’s right in the world, right?
You’ve got a bad thermostat and you need to fix it asap. If your thermostat starts taking a longer time to open, or if it doesn’t open at all, your engine will be at risk for a full-on overheating event.
The good news is that replacing a thermostat is an easy job. You can probably do it yourself in under an hour. And if you take it to a mechanic, it won’t be an expensive job at all.
One other possible cause for your car overheating then going back to normal is a bad radiator fan.
Most cars use electric radiator fans to suck cool air through your car’s radiator. Contrary to what you might think, these fans don’t blow air directly onto the radiator. They sit behind the radiator and blow air towards your car’s engine. This orientation helps draw cool air through the radiator.
If your radiator fan goes bad, airflow through the radiator is reduced, decreasing the radiator’s ability to cool down the coolant.
This condition gets problematic when your car is idling or going slow. Your car isn’t moving fast and receiving the additional benefit of cool air being forced into the radiator through the grill.
A typical scenario would be if you get stuck in highway traffic. Because your radiator fan is broken, it can’t help draw in air and your car may start to overheat. But as soon as traffic clears and you start moving fast, cool air is naturally forced onto the radiator. Your car’s temperature goes back to normal and all’s well with the world, right?
Just like with a bad thermostat, a bad radiator fan may put you in a situation where you’re at risk for an overheating event that can cause expensive damage to your engine.
Depending on your car, replacing a radiator fan can get a little tricky because it could be difficult to access. It’s a doable job, but may require a little time and patience.
A car overheating then going back to normal is a serious problem. Don’t take comfort in the fact that your car’s problem seems to go away on its own. It’s only a matter of time before your problem gets worse and your car temperature might NOT go back to normal. Likely causes for this condition are either a bad thermostat or bad electric radiator fan. If neither one of those parts are the culprit, move on to some other possible causes. Check out this article for some ideas. Good luck!
Header photo credit: Todd Huffman