Car running hot but not overheating: Causes and Fix guide

Has your car ever been running hot but not overheating?

It is a problem associated with an engine’s cooling system. For most drivers, it can be difficult to detect as most cars no longer have temperature gauges. What happens is that there will be a red engine light on your dashboard.

What should you do when this occurs? In this article, we will explain to you what could be the cause of this, running diagnostics and how to fix it.

Why is your car running hot but not overheating?

After you’ve noticed that your car is running hot but not overheating, you will need to check its cooling system for:

  1. A dysfunctional Water Pump

Car water pumps on average last the lifetime of a car. But in some cases, they may start failing after being in use for a long time. When this happens, it can lead to your car running hot.

It is advisable to check on your water pumps as a precaution. Especially if the engine runs hot often, you may have to change them.

  1. Low levels of coolant

The amount of coolant you put in your car is dependent on the size of your engine. The work of the coolant is to regulate engine temperature by taking heat from the engine. Coolant moves around the engine through the water pumps.

If your car does not have enough coolant, your engine could run hot. The coolant helps prolong the life of the engine. It comprises water and antifreeze. The antifreeze plays an important role:

  • It has rust inhibitors that protect the internal makeup of the engine.
  • It enhances the thermogenic properties of water that always remains cool under all temperature conditions.
  1. Impure composition of the coolant

After being in circulation for a while, the quality and strength of the coolant will naturally decrease. As a result, it will not efficiently pick heat from the engine which will then lead to it running hot. We recommend changing it after every two years. Failure to which impurities it picks up over the cause of this time will weaken it.

  1. Faulty Engine Coolant Thermostat

A coolant thermostat is a major component of the cooling system. It regulates the flow of coolant in the engine to keep creating a conducive temperature atmosphere for the engine to operate. It works by measuring engine temperature and allowing circulation of the coolant depending on the reading.

Over time, they can become less effective. With this, coolant flow to the radiator may not happen in time and thus the engine will run hot.

  1. A Faulty Cooling Fan

This is another common cause for an engine running hot but not overheating. The work of the cooling fan is to regulate the temperature of the regulator by supplying cool air, especially in traffic. If the cooling fan is faulty, the engine may run hot.

What should you do next?

  1. How Do You Diagnose Engine Hot But Not Overheating Problems?

Unless you are a car and engine expert, you need an OBDII diagnostic scanner to help you identify the cooling system problem. Diagnostic scanners will allow you to have engine details such as engine temperature in real-time. They allow you to notice any signs of potential cooling system trouble.

With the help of a code reader, check the following:

  • Coolant leaks: Coolant leaks will lower the amount of coolant available in the engine, which will cause the engine to run hot.
  • Check on the cooling fan: Ensure that the auxiliary cooling fan is functioning at maximum capacity. Fans are made of plastic which is susceptible to damage. Their blades can also wear out over time which reduces their strength. 

When checking the fan’s condition, ensure that the blades are running freely.

  • Check for leaks in the radiator: Ensure that there are no coolant leaks in the radiator. Also, check that there is no damage to radiator fins as they may interfere with coolant flow.
  • Inspect cooling system hoses: The rubber in this system can suffer damage such as tears. Check to make sure that they are in optimal condition. Ensure that hose joints are also okay and do not have any damage that could cause leakages.
  • Conduct a full flush on the coolant system: It helps in ridding the system of any foreign particles or debris.
  1. How to fix cars running hot but not overheating?

Any potential problem with the engine should be taken seriously. An overheating system could be because of several different reasons as seen earlier. They could lead to damage to the whole engine If left unattended.

Observe how the temperature gauge behaves as you drive. If it’s in the middle, this is an indication that there is a problem. Normally, it should be between the cold and midpoint mark. However, most modern cars do not have a temperature gauge. If your vehicle falls in this category, be on the lookout for a red light indicating a potential problem with the engine.

When you notice any potential concern with your engine running hot, park your car and run diagnostics. We recommend the use of an OBDII scanner for this. If you are not sure how to solve the problem, consult a reputable mechanic. 


An engine running hot but not overheating is a common occurrence. Make sure that you are observant because if this is left to run over a long time, it could cause irreversible damage to your engine. Make sure you have your diagnostic scanner tool with you to check on engine temperature and run error codes in case of a problem. Your engine running hot should not stress you, but make sure you have it fixed immediately!

Author: Brandon Park