It is very important to keep an eye on the coolant temperature reading on your instrument cluster. Auto manufacturers install coolant temp sensors and temp gauges to help drivers track the engine and coolant temperature while driving.
As technology evolves in the automobile space, more features and computers are installed on newer cars.
Some of these sensors are there to track temperature (we’ll get to it later on). Once the coolant temperature is high, one of these sensors will register a trouble code on the car computer.
These features have helped protect our vehicles from engine overheating by notifying the driver when something goes wrong.
In this article, we’ll discuss at length where your coolant temperature should be, how to fix high coolant temperature, and how the symptoms of a bad coolant temp sensor. Sit back and read the provided information.
What is Coolant Temperature?
Coolant temperature refers to the temperature of the liquid coolant that circulates through your vehicle’s engine, radiator, and cooling system.
This liquid is designed to absorb and dissipate heat generated by the engine, keeping it running at a safe and efficient temperature.
How is Coolant Temperature Measured?
Coolant temperature is typically measured using a temperature gauge or sensor located in the cooling system.
This sensor sends a signal to the dashboard, displaying the temperature reading in degrees Fahrenheit or Celsius. Some modern vehicles may also feature electronic temperature gauges or digital displays.
Symptoms of High Coolant Temperature
Here we won’t be talking about engine overheating symptoms since those are pretty obvious and are best left for another article.
Instead, we will talk about the symptoms of a hot running engine, where it’s not overheating fault codes and warning lights but isn’t running optimally either.
#1. Higher Fuel Consumption.
As the ECU notice that the engine coolant temperature is slightly higher than it’s supposed to be under the given conditions, it will enrich the air/fuel ratio. In other words, add more fuel to the combustion chamber.
The excess fuel acts as a cooling agent and carries heat away from the cylinders and into the exhaust. That means raw and unburnt fuel is escaping into the exhaust, which noticeably increases fuel consumption.
#2. Poor Performance.
One of the things the ECU does to lower the combustion chamber temperature is retard the ignition timing.
Retarding the ignition timing means the spark plug fires later than what would be optimal, which reduces the amount of time the fuel is burning inside the cylinders.
That will quickly lower the temperature but also significantly reduce performance since a lot of the combustion expansion is wasted.
#3. Black Smoke.
Black smoke will be most noticeable in diesel engines but can happen in gasoline engines as well, although not as apparent.
Black smoke is a common byproduct of a rich air/fuel mixture and unburnt fuel going into the exhaust, which we already explained why it happens.
#4. Backfires.
Backfires are extremely common in vehicles with ignition timing problems or when the ECU retards the timing intentionally to cool the engine. The backfires occur because the spark plugs are firing late during the compression stroke.
In extreme cases, spark plugs will fire so late that the fuel will still be burning as the exhaust valve opens and shoots out of the exhaust.
The same thing happens because of a rich air-fuel mixture. We already mentioned that a lot of unburnt fuel goes into the exhaust, which heats the fuel up, and as it nears the muffler and mixes with oxygen from the atmosphere, the fuel lights up and explodes out of the exhaust tips.
What are the Causes of High Coolant Temperature?
There are several reasons why your coolant temperature may be too high, including:
- Low coolant levels: Insufficient coolant can cause the temperature to rise, as the liquid is unable to effectively absorb and dissipate heat.
- Clogged radiator: A clogged radiator can restrict airflow, causing the temperature to increase.
- Faulty thermostat: A malfunctioning thermostat can prevent the engine from reaching its optimal operating temperature, leading to increased heat.
- Engine problems: Issues with the engine, such as worn piston rings or a faulty head gasket, can cause the temperature to rise.
How to Check Coolant Temperature
As we just mentioned, the factory temperature gauge in any car isn’t precise and cancels out all the normal temperature fluctuations. But if you want a precise coolant temp readout, there are ways you can access it.
That will give you a better insight into how the engine is operating at what conditions and whether or not there is a fault in some of the systems.
For example, this can reveal if the thermostat is faulty, the radiator fan, if the coolant passages are clogged, if the coolant temperature sensor is bad, and more.
#A. OBD2 Bluetooth Adapter.
OBD2 Bluetooth adapters have become extremely popular in the past decade for a couple of reasons. They are easy to use, they are precise, they let you scan and delete fault codes, and they give you a data readout in real-time on your smartphone.
One of the parameters you can keep track of is the coolant temperature, and you will get a precise readout just like you would with a professional tool.
You can pick these up for about 20 bucks on Amazon, and the only other thing you need is to download a free corresponding app on your smartphone, and that’s it.
#B. OBC (On Board Computer).
This isn’t a possible method for all makes, and models, but some cars will let you read different engine parameters through the onboard computer, including the coolant temperature.
But accessing this information requires special procedures that you can only find on forums.
I also can’t tell you which vehicles have this option, but doing a quick search with your vehicle’s make and model will reveal everything you need to know. What I can tell you is that all BMWs with OBCs have this option.
#C. OBD2 Scanner.
Using a professional OBD2 scanner with a laptop and professional software will get you the most accurate coolant temperature readout in real-time as well as every single other parameter the ECU keeps track of.
If you want an accurate coolant temperature readout to help you diagnose a problem instead of just out of curiosity, this is the best method.
But keep in mind that these tools and software cost over $300 in most cases, so you are better off taking the car to a professional and spending $50 for a professional diagnosis.
#D. Aftermarket Temperature Gauge.
You will find a whole slew of different aftermarket coolant temperature gauges, from analog to digital and from those that tap into the existing wiring to those that come with a standalone coolant temperature sensor.
In this case, you are better off getting one with a designated temperature sensor, as it will give you a more precise readout.
Unfortunately, installing such a gauge can be extremely time-consuming, plus you will end up with a tacky gauge in your dashboard which isn’t to everyone’s liking.
But if you need a constant and precise coolant temperature readout, an aftermarket gauge is your best option.
Normal Coolant Temperature Range
Most vehicles, regardless of engine size or fuel type, run with a coolant temperature of 190 to 220 degrees Fahrenheit.
That goes for both gasoline and diesel engines. But since most vehicles don’t have temperature numbers on the coolant temperature gauge, the normal operating temperature is right in the middle.
Anything past the middle is considered running hot, and anything under that is running cold.
It’s also worth mentioning that coolant temperature fluctuations are entirely normal, and you will notice that the engine is running hot while cruising and cools down as soon as you start to accelerate a little harder.
At least, that’s the case for engines that have electronically controlled thermostats. The reason manufacturers set them up this way is that a hotter combustion chamber means the fuel burns more efficiently and causes less pollution.
But a hotter combustion chamber requires a retarded ignition timing which lowers performance.
This is why as soon as you open the throttle, the ECU opens the thermostat to cool down the combustion chamber and then advances ignition timing to free up more horsepower from the engine.
But keep in mind that the standard coolant temperature gauge has a 5-7 degree Celsius buffer, so you won’t notice all these fluctuations in real-time.
Instead, the temperature gauge will remain in the middle as long as the coolant temperature is within range, and only as it crosses 105C or 220F will it begin to move.
If the temperature passes 110C or 230F, you will most likely get a coolant temperature warning light and a check engine light indicating that the engine is overheating.
What Coolant Temperature Is Too Hot?
What coolant temperature is too hot depends on the engine. For some engines, anything over 210 (95C) degrees Fahrenheit is too hot, while for others, anything over 220 (105C) is considered overheating.
But we can say that there won’t be any long-term engine damage as long as the coolant temperature doesn’t cross 230F.
Is low coolant temperature also a bad thing?
Similar to the way that coolant that is too-high in temperature can be an issue, coolant that is too-low in temperature can cause problems as well:
- Reduced Engine Efficiency: Engines are designed to operate at optimal temperatures. When the coolant temperature is too low, the engine may not reach its ideal operating temperature, leading to reduced efficiency.
- Increased Fuel Consumption: A cold engine requires more fuel to run properly. This is because the fuel does not vaporize as easily in a cold engine, leading to incomplete combustion and higher fuel usage.
- Increased Emissions: Cold engines produce more emissions because the combustion process is less efficient. This can lead to higher levels of harmful pollutants being released into the environment.
- Poor Heater Performance: The vehicle’s heater relies on hot coolant to warm the air that is blown into the cabin. If the coolant is too cold, the heater will not function effectively, leading to an uncomfortable driving experience in cold weather.
- Engine freeze: if the temperature is so low that it is possible for your radiator to get too cold, this can result in your engine freezing up and the car not being able to start.
How do you fix high coolant temp?
- If you notice a high coolant temperature while cruising on a sunny hot afternoon, do not panic. Instead, turn off the air conditioner to reduce the list on the engine. Then turn on the heater.
- Don’t keep driving; find a safe place and pull over. Turn off the engine and allow it to cool for about 20-45 minutes. Call a friend or mechanic to tow your car.
- Check things out. Inspect your cooling components and check the coolant level. If the coolant is low, top it with antifreeze( If you have any). This will help get your engine back to normal operating temperature.
- If you did not start your car earlier, start it and inspect how the components are working. Gently drive your car to the nearest auto garage for thorough inspection and fixes.
How to Maintain Optimal Coolant Temperature?
Maintaining optimal coolant temperature is crucial for the longevity and performance of your vehicle. Here are some tips to help you achieve the perfect temperature:
Regular Maintenance
Regular maintenance is key to ensuring your coolant temperature remains within the recommended range. Schedule regular check-ups with your mechanic to:
- Check coolant levels: Ensure the coolant levels are at the recommended level to prevent overheating.
- Inspect the radiator: Check the radiator for any signs of damage, corrosion, or blockages.
- Replace the thermostat: If your thermostat is malfunctioning, replace it to ensure proper engine temperature regulation.
Additional Tips
In addition to regular maintenance, here are some additional tips to help you maintain optimal coolant temperature:
- Monitor your temperature gauge: Keep an eye on your temperature gauge to ensure it’s within the recommended range.
- Avoid extreme temperatures: Avoid driving in extreme temperatures, such as extremely hot or cold weather, to prevent engine damage.
- Use the correct coolant: Use the correct type of coolant for your vehicle, as specified in your owner’s manual.
FAQs.
Q: What temp is too high for coolant?
Normal coolant temperature Celsius should be between 75 to 195 degrees. If your engine runs higher than this, consider inspecting your cooling system components.
Prevention is better than cure, they say. You wouldn’t want to damage your engine parts which will result in an expensive fix because of ignorance or not inspecting your vehicle.
Q: Why is my engine bay so hot?
If your temp gauge or temp warning light consistently shows your engine is overheating, or your engine bay is running so hot, you need to check your cooling system components immediately. Fix or replace any faulty components.
Q: Is engine temperature the same as coolant temperature?
The engine temperature is usually hotter than the coolant temperature, especially around the cylinders. However, engine and coolant temp is considered to be the same since the engine and coolant temperature are usually controlled by one sensor.
Coolant temperature sensors are usually found on the cylinder head, and mostly on the pipe that transports antifreeze from the radiator to the thermostat. This demonstrates that this sensor monitors both engine and coolant temp.
Final Word
Ensuring your cooling system components are working optimally is key to keeping your engine temperature as it should.
So, if you suspect your coolant temperature is running high, make sure your system is working properly by diagnosing your vehicle and fixing or replacing any damaged parts.
As I always advise, if you’re not a car enthusiast or a petrolhead who knows the working principles of the underhood components, seek professional advice to avoid causing injury to yourself.
In case you choose to check your coolant level, allow the engine to cool down before opening the radiator cap. If you open it when it is still hot, it’ll splash hot water on your face.