Troubleshooting 6.7 Cummins Coolant Temp Fluctuations: An Essential Guide

The 6.7 Cummins engine may be experiencing an overheating issue, caused by a faulty cooling system component or low coolant levels, which can lead to coolant temperature fluctuations.

6.7 Cummins Coolant Temp Fluctuating

The 6.7 Cummins Coolant Temp Fluctuating issue can be a confusing one, especially if you dont know what to expect or why it is happening. This fluctuating coolant temperature can be caused by several different issues such as low coolant, thermostats and sensors stuck open or closed, faulty cooling fans, and incorrect fuel pressure. In order to solve the problem, it is important to identify the exact cause of the fluctuation to ensure a proper resolution.

Once you have determined the source of the temperature change, there are several things that must be done in order to correct the problem. This can include repairing or replacing parts that may be damaged as well as checking for loose connections that may be causing an incomplete circuit in the system. It is also important to make sure all filters are clean and replaced when needed. Lastly, it is important to check and adjust fuel delivery pressure.

Regardless of what specific issue you come across with your 6.7 Cummins Cooling system, addressing them quickly and correctly will help save time and money while ensuring optimal performance and safety of your vehicle.


The 6.7 Cummins coolant temperature fluctuates when the engine is running, and this can cause a range of issues. It is important to understand why this occurs and how to troubleshoot it to ensure that your engine runs properly and safely. In this article, we’ll discuss what causes the 6.7 Cummins coolant temperature to fluctuate, how to diagnose the issue, and tips for keeping your engine running at its best.

What Causes the 6.7 Cummins Coolant Temperature Fluctuate?

The 6.7 Cummins coolant temperature fluctuates due to a variety of factors, including air temperature outside, air pressure inside the engine, load on the engine, and other factors. The most common cause is an imbalance between air pressure inside the engine and outside air pressure. When these two pressures are not equal, it can cause a vacuum effect which will draw in additional air that is not heated or cooled by the radiator or other cooling components. This will result in an increase or decrease in coolant temperature depending on which direction the pressure imbalance is in.

Other factors that can contribute to coolant temperature fluctuations include thermostat malfunctions, clogged radiators or hoses, leaks in the cooling system, incorrect fan speeds, poor circulation of coolant through the system, or faulty sensors or wiring in the vehicle’s computer system. All of these issues need to be addressed before any meaningful diagnosis can be done.

How To Diagnose The Issue

In order to diagnose a fluctuating 6.7 Cummins coolant temperature issue correctly and efficiently you must first identify what exactly is causing it by finding where the issue originates from within the engines cooling system. To do this you must first inspect all components of your cooling system such as hoses and radiators for any signs of leaks or blockages which could be causing an imbalance of pressure within your system resulting in a change in temperatures within the coolant fluid circulating throughout your engines block & heads. Once any potential issues here have been identified & rectified you should then check for any faults with fan speed settings & overall circulation efficiency as these can also affect temperatures within your cooling system if set incorrectly or not working up-to-specification respectively (i.e water pump). Finally look into any potential faulty readings from sensors & wiring problems as these are both common culprits when it comes to misreading temperatures within your vehicles computer systems resulting in inaccurate readings being displayed & further incorrect decisions being made by said systems based upon them (e.g incorrect fuel/air mixture).

Tips For Keeping Your Engine Running at Its Best

Once you have identified and rectified any issues causing fluctuations in 6.7 Cummins coolant temperatures there are some simple steps that you can take to ensure that they stay stable over time:

  • Regularly check all components of your cooling system for wear & tear such as hoses & radiators.
  • Make sure fan speeds are set correctly according to manufacturer specifications.
  • Ensure that there is enough water/coolant mix within your radiator.
  • Check all sensor readings regularly.
    • Following these steps will help keep your 6.7 Cummins running smoothly with no fluctuations in temperatures so long as all components remain working correctly & together efficiently without fault – something every car owner should strive for!


      The 6.7 Cummins Coolant Temp Fluctuating can be a worrisome issue for Cummins owners. It can cause a wide range of problems, from poor fuel economy to engine damage. It is important to understand the causes and how to address them in order to keep your engine running at its peak performance. This article will discuss the different causes of coolant temperature fluctuation, what you can do to fix it, and how to prevent it in the future.

      Causes of Fluctuating Temperature

      There are several possible causes of 6.7 Cummins coolant temperature fluctuation. These include:

      • Coolant Leak: A coolant leak can cause the engine coolant level to drop and lead to temperature fluctuations.
      • Thermostat Failure: The thermostat regulates the flow of coolant through the engine by controlling its temperature. If it is faulty or stuck, it can lead to temperature fluctuations.
      • Radiator Issues: The radiator is responsible for cooling the engine by dissipating heat away from it. If there are any issues with its design or build, this can lead to temperature fluctuations.
      • Faulty Sensors: Faulty sensors within the cooling system can interfere with proper operation, leading to temperature fluctuations.

      Fixing Fluctuating Temperature

      In order to fix 6.7 Cummins coolant temperature fluctuation, you will need to address any underlying issues causing it. This may include repairing or replacing any faulty components such as thermostats, radiators, or sensors. Additionally, you may need to inspect for any leaks and repair them as necessary. Once all underlying issues have been addressed, you should be able to return your engine’s cooling system back into proper operation and reduce any further temperature fluctuations occurring in your vehicle’s engine bay area.

      Preventing Fluctuating Temperature

      In order to prevent 6.7 Cummins coolant temperature fluctuation from happening again in the future, there are a few steps you can take. First off, make sure that all components within the cooling system are properly maintained and inspected regularly for signs of wear or damage that could lead to failure later on down the line. Additionally, make sure that all seals and gaskets are properly fitted and not leaking as this could lead to further problems in your cooling system down the line as well as introduce air into your system which could contribute towards severe overheating problems if left unchecked for too long. Finally, ensure that your vehicle is serviced regularly so that any potential issues with your cooling system can be identified early on before they become more severe over time due

      FAQ & Answers

      Q: What causes a 6.7 Cummins coolant temperature to fluctuate?
      A: The most likely cause of the 6.7 Cummins coolant temperature fluctuating is a faulty thermostat, a clogged radiator, low coolant levels, or an air pocket in the cooling system.

      Q: How can I tell if my thermostat is causing the temperature fluctuations?
      A: You can check and see if your thermostat is functioning correctly by watching the gauge on your dashboard. If it goes up and down drastically, it may be an indication of a faulty thermostat.

      Q: What are some signs that my radiator might be clogged?
      A: Some signs that your radiator may be clogged include long warm-up times when starting your engine, low coolant levels, and an increase in engine temperature even after running at normal speed for an extended period of time.

      Q: How do I check the coolant level in my 6.7 Cummins?
      A: To check the coolant level in your 6.7 Cummins engine, first make sure that the engine is off and cooled down before removing the cap from the radiator or reservoir tank. Then look at the side of the reservoir tank to find out what level it should be at when full. If it’s below that level, add more coolant until it reaches the correct level.

      Q: What should I do if there’s an air pocket in my cooling system?
      A: If you suspect that there may be an air pocket in your cooling system, you will need to bleed it out by opening a valve near the top of your radiator or reservoir tank and allowing any trapped air to escape until you see a steady stream of liquid coming out with no bubbles or breaks in flow.

      The 6.7 Cummins Coolant Temp Fluctuating can be caused by a number of different issues such as a failing thermostat, a blocked radiator, or an air pocket in the system. In order to resolve this issue, it is important to first identify the root cause of the issue and then take the necessary steps for repair. With proper diagnosis and repair of the underlying issue, your 6.7 Cummins coolant temperature should return to normal levels.

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