Is your car overheating then going back to normal — as if nothing happened?
Well, engines are supposed to heat up when you drive and cool down once turned off. But if you’re driving and an overheating car suddenly returns to normal, you might have a faulty cooling system.
If left unchecked, this condition can cause severe engine damage.
This Article Contains
- Why Is Your Car Overheating Then Going Back to Normal? 9 Potential Reasons
- 3 FAQs on Engine Overheating
Let’s get started.
Why Is Your Car Overheating Then Going Back to Normal? 9 Potential Reasons
The combustion of fuel in the engine produces a high amount of heat which needs to be expelled to ensure the engine works properly. However, if your overheating car suddenly cools down, it could indicate internal issues that need immediate engine repair.
Here are some of them:
1. Bad Thermostat
The thermostat is a plug that senses internal engine temperature and controls the flow of hot water into the radiator. It has a spring attached inside that pushes the plug open when the engine reaches its normal operating temperature.
A faulty thermostat (broken or stuck) loses its ability to detect heat properly, so it reacts to higher temperatures than usual. Hence more heat accumulates, and the temperature rises — causing engine overheat.
The symptoms of a bad thermostat include:
- Car overheating even at low speeds and takes longer to warm up
- Coolant temperature gauge is red or gives a false reading
- Rumbling noises coming from the engine
2. Low Coolant Level
Coolant is a specific fluid used to maintain the engine’s normal operating temperature. It absorbs heat as it flows through the engine block and releases heat through the radiator. Lack of engine coolant can cause overheating.
Low coolant in the coolant tank is caused by a cooling system leak, or if you forgot to refill it. Without enough coolant, your engine might be driving at high temperatures.
Symptoms of a low coolant level are:
- Visible bubbles in the coolant
- Steam coming from the exhaust system
- Dirty and frothy-looking radiator fluid
3. Faulty Radiator
Your car’s radiator removes heat from the engine by cooling down the hot coolant that flows through. If the radiator is faulty (broken radiator fan, leaking radiator hose, or busted radiator cap), it could result in a coolant leak and affect its efficiency.
Whereas a dirty or blocked radiator could restrict the coolant flow in the cooling system, causing less coolant to enter the engine. You may also see steam coming out of the car hood.
Other signs of a faulty radiator include:
- Decrease in engine power
- Strange loud noises coming from the engine
- Faulty thermostat reading
4. Water Pump Malfunction
The water pump circulates coolant through the cooling system. It also prevents hot water from getting stuck in one part of the coolant system. A stuck or failed water pump restricts coolant flow and reduces the efficiency of the coolant system, causing car engine overheating
However, when checking for a faulty water pump, you should also have the engine serpentine belt inspected.
Here are some symptoms of a broken water pump:
- Loud knocking noise from the engine
- Loss of engine power
- Decreased fuel efficiency
5. Bad Engine Sensors
Plenty of sensors are connected to your engine, each with its specific role. In terms of a car overheating then going back to normal, you can suspect a faulty coolant temperature sensor.
The sensor detects the engine’s temperature and is connected to the temperature gauge on your dashboard. The faulty sensor could send false signals, and your car temperature gauge would suddenly rise and fall — making it seem that your car is overheating and then returning to normal.
Signs of a faulty engine sensor are:
- Air conditioning and heater malfunction
- Warning lights that go on and suddenly turn off
- Reduced fuel economy
6. Low Engine Oil
Sometimes low engine oil could also cause overheating. This is because, other than lubricating the engine, it also lowers the temperature of the moving components (pistons, valves, etc.).
When the engine oil level is too low, the temperature can build up in these components and cause an overheated engine. If you’re experiencing low engine oil, stop driving immediately, as it could cause more than just an overheating problem.
Symptoms of low engine oil include:
- Activated oil pressure warning light
- Burning oil smell
- Strange noises from the engine
7. Clogged Heater Core
The heater core works as a heat exchanger by controlling coolant flow.
Hot coolant from the engine flows into the heater core, and heat is released into the car’s cabin. If the heater core is clogged, it prevents hot coolant from entering the heater. This causes the coolant temperature to rise, leading to overheating.
The symptoms of a clogged heater core are:
- Warm air exiting the air vents, but the car isn’t warm
- Coolant leaks at the front wheels with a strong sweet smell
- Car temperature gauge readings that are unusually high or low
8. Loose Serpentine Belt
A loose serpentine belt can also cause an overheated engine.
The serpentine delivers power to several components under the car hood— like the water pump. If you have a loose engine belt, there would be insufficient force to push the coolant into the engine block.
Here are some of the signs of a loose engine belt:
- Loud noises or squealing from under the hood (especially when accelerating)
- Engine components cease to operate (water pump, power steering, etc.)
- Activated check engine light or other warning lights
9. Blown Head Gasket
The head gasket is a vital component of your engine that seals off the engine compartment from the combustion chamber. Essentially, it stops the high-pressure combustion gasses, coolant, and engine oil from mixing.
Signs of a blown head gasket include:
Figuring out the root cause of a car overheating then going back to normal is tricky. Your check engine light may also pop on with any of these symptoms. Since there are plenty of components to look into, it’s best to leave it to the professionals.
Now, time to answer some FAQs.
3 FAQs on Engine Overheating
Here are the answers to some common questions about a car overheating:
1. What Should I Do If My Car Is Overheating?
Here are some steps to do if the engine overheats:
- Find a safe place to park and immediately turn off the engine.
- Next, let the engine cool off for a few minutes.
- Don’t immediately open the hood because the steam coming out is VERY HOT, and you’ll risk burning yourself.
- After the hood has cooled down, open the hood and inspect your coolant level.
- If it’s low and you have a bottle of engine coolant on hand, refill the coolant reservoir until the required amount or contact your mechanic.
However, if you have to drive to the nearest workshop, go slowly with the heater on and turn off other accessories. It might get uncomfortable, but this helps reduce overheating by redirecting the heat from the car engine.
2. Can a Car Overheat When Idle?
Yes, cars can overheat when idle.
When you drive, the air flowing into the hood is sufficient to cool the engine block. But when idling, there’s no air drag to blow off the heat, so the radiator is the main cooling device.
If a radiator component (electric fan, loose radiator cap, etc.) malfunctions, it can cause overheating when idle.
3. Can I Drive With an Overheating Engine?
No, you can’t.
If your engine is overheating, you should immediately find a safe place to stop. Never drive more than a quarter of a mile with an overheating engine.
What happens if you continue to drive?
First, the engine components will distort and crack. The cylinder heads start to deform, causing severe engine damage, and it stops working. There’s also a small chance that your car might catch fire.
With that said, it’s best to stop driving to avoid costly engine repair and for your safety.
A hot spike in engine temperature is a driver’s worst nightmare. It gets even more concerning and confusing when car overheating suddenly returns to normal. This phenomenon can happen for many reasons, like a bad thermostat, a faulty radiator, or a coolant leak.
As such, it’s best to get your car checked by a professional— like RepairSmith!
Repairsmith is a mobile auto repair and mechanic service. Our mechanics are fully equipped with all the necessary tools to get your engine inspected, prevent overheating, and much more.
Contact us today, and we’ll send our best mechanics to your driveway!