The Most Common 6.7 Cummins Problems

The 6.7 Cummins is the latest diesel engine of the B series engines. The engine has been upgraded as of 2021 to ensure that it gives you an impressive 400hp and 1000tq. However, even with all the good and amazing features, no engine is perfect, and 6.7 Cummins is no exception.

The engine has its downsides and features that you can rely on whenever you think of replacing your engine with a Dodge Ram 6.7 Cummins engine. Cummins is a name that is associated with greatness when it comes to diesel engines. However, that should not limit your need to check out the engine. Some of the common problems with 6.7 Cummins include:

  • EGR cooler
  • Turbo failure
  • Fuel dilution
  • Clogged DPF
  • Head gasket

Here, we'll talk more about the common 6.7 Cummins problem to give you a better understanding of the engine.

Turbo Failure

Turbo problems are quite common with 6.7 Cummins engines. The issues can develop at any level as the turbo undertakes serious abuse. However, not all turbo issues are directly related to the turbo, nor do other lead to complete failure. Some of the issues that you should expect under this category include:

  • Sticking VGT parts
  • Leaking oil seals
  • Turbine or compressor wheel damage
  • Worn bearings

Worn bearings and leaking oils are commonly associated with turbo aging. The 6.7 Cummins turbo can run up to 100,000 RPM's. When you exceed this mark, the turbo bearings will wear down, leading to excessive shaft play. However, this might not lead to complete failure if you allow the compressor wheel and turbine to contact the turbo housing.

To prevent such issues, it is convenient to keep checking on your turbo regularly. Turbos run off hot exhaust gas, so you should ensure that the oil reaches the operating temperatures before pushing the engine too hard.

When the oil is cold, it could lead to turbo seal issues if it splashes to the hot turbo seals. Therefore, you should allow your engine to idle for a little longer before shutting it down. This way, the turbo will cool hence prevent any possible issues that may occur.

Although this problem might occur at any point, checking on the mileage is critical. If your 6.7 Cummins engine is a hybrid, replacing the turbo might be convenient once you hit the 120 000 miles mark. However, you can also choose to rebuild the turbo if it is not completely worn out.

Fuel Dilution

The issue with fuel dilution in the 6.7 Cummins engine is inherent based on how it manages regeneration. Fuel dilution is the process where particulates are trapped in DPF and later burned for cleaner emissions. Since the 6.7 Cummins engine doesn't use the 7th injector into the fuel exhaust, it makes the oil splash into the fuel hence developing issues.

The standard dilution limit for a Dodge Ram 6.7 Cummins is 5%. If your engine experiences anything higher than this, then the possibilities of encountering problems are super high. Too much fuel on the oil cylinder can lead to fuel and oil mixing.

Although the mixture may not severely damage the engine immediately, it is essential to prevent the issue before it occurs.

Clogged DPF

(DPF) diesel particulate filter clogging is a common problem on the 6.7 Cummins engine. The clogging in DPF leads to numerous problematic issues on how the engine operates. The move to change Dodge Ram 5.9 Cummins to 6.7 Cummins lead to a number of updating. These updates enhanced the turbo lag making it easy to drive the truck.

However, with the enhanced changes, the clogged DPF, although it was aimed at improving the engine's performance. As a powerful truck, the 6.7 Cummins still experiences problems, which was attributed to various turbocharger functionality. Some of the issues that contribute to the DPF clog problems include:

  • Long crank
  • Power loss
  • Engine fault codes
  • Reduced power mode

With this in mind, the best way to resolve the problem is by replacing the DPF. Although it's a piece of expensive emission equipment, replacing the piece guarantees that the engine will regain its power and also ease the mobility process.

Head Gasket

Head gasket problems in 6.7 Cummins often come as a result of the torque and sheer power that the Dodge Ram 6.7 makes. It also has high cylinder pressure, which also might be a big contributor to head gasket issues. The common issues that contribute to head gasket failure include:

  • Overheating
  • Whitish smoke with a sweet smell
  • Coolant mixed with oil
  • Oil mixed with coolant

When the engine is on, the head gasket blows, allowing the coolant into the combustion chambers. This generates white smoke that is passed through the exhaust. The smoke has a sweet smell, but it combines with oil, which happens at times. When the oil and coolant mixture remains at the head gasket for a longer time, it results in developing issues to the engine.

EGR cooler

When it comes to 6.7 Cummins problems, the EGR cooler is not an exception. Being part of the emission system, the EGR cooler experiences issues that are related to higher mileage. The easiest way of resolving the problem is by cleaning the valve. This ensures that you eliminate any possible problems forming right before the start to be a problem.

On the other hand, you can also resolve the issue by deleting or replacing the parts. If the problem occurred due to higher mileage, replacing the part often proves to be the easiest way of resolving and regain the initial 6.7 Cummins performances.

The upgraded 6.7 Cummins ensures that driving your truck is an interesting adventure. It gives you the assurance that your trip will be exceptional in various circumstances. However, with all the goodness of the engine, it is critical for you to extra vigilant as there are also issues that still challenge the operations of the 6.7 Cummins.


I am Samantha, an automobile engineer and POD business owner. I am also a wife of Jason and a mother of three children, two of whom are twins. I am passionate about making a difference in the world and strive to be a role model for my children. I believe that hard work and dedication can lead to success, no matter what your circumstances may be. I have a passion for cars and enjoy working on them in my spare time. I am excited to be able to share my knowledge and experience with you. Stay connected !

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