The 6.7 Cummins is one of the most popular diesel engines in the world. It has a reputation for being incredibly durable, powerful, and efficient.
While this means it’s used in everything from commercial trucks to personal vehicles like pickup trucks and SUVs, not all were built equally.
Though all 6.7 Cummins engines run differently depending on usage and other factors, you should avoid 2009, 2011, 2014, and 2015 6.7 Cummins engines. Collectively, these engines have had issues with DPF clogs and turbocharges. The 2011 model even went through a recall.
Below, I’ll discuss why you should avoid these models and give you some insight into what issues they may bring up for your vehicle. Additionally, I’ll give you a brief overview of the 6.7 Cummins.
1. 2011 6.7 Cummins Engine
The 6.7L Cummins diesel was first introduced in the Ram 2500 and 3500 pickups in 2009. If you’re looking for a used truck with a good engine, it’s best to avoid the 2011 model year. This is because of the powertrain warranty problems that arose with this engine.
The 2011 model year saw many failures of these engines due to problems with their injectors, which led to recalls being done by both Chrysler and Cummins (the manufacturer).
Reasons To Avoid
Most commonly, 2011 dealt with issues, including:
- DPF clogs
- Turbocharge issues
- Head gasket problems
All of these issues are fixable but a pain. If you did find that your 6.7 suffered from any of these, learn more about the recall and see if your vehicle was affected.
DPF Clogged
When a vehicle’s diesel particulate filter (DPF) gets clogged, it can cause the engine to run rich, which translates to poor fuel economy and mileage. This can also lead to excessive carbon buildup in the exhaust system and an increased risk of failure.
When the DPF gets clogged, it leads to premature DPF failure, where chunks of soot will fall off and get burnt in your engine.
Imagine raw carbon smeared on your engine’s air filter; hot air burns the soot to create smoke. This damage can reduce your fuel efficiency by 30% and make your truck harder to drive than usual.
Turbocharge Issues
The turbocharger on your 6.7 Cummins can fail without warning, leaving you stranded in the worst possible place.
At best, it may affect engine performance and fuel economy. At worst, it could lead to the engine stalling or potentially catching fire in traffic while driving!
Head Gasket Problems
When the head gasket has an issue, it can cause catastrophic engine failure and expensive repairs. The head gasket is between the engine head and block to ensure that coolant, oil, and exhaust all flow where they should. Your engine needs to have a working head gasket to run at maximum efficiency.
EGR Valve Issues
The EGR might have a problem. This is an emissions device that helps regulate fuel efficiency by mixing exhaust gasses with fresh air before entering the engine’s combustion chamber.
If it fails, carbon buildup can occur quickly and cause damage inside your engine compartment.
2. 2009 6.7 Cummins Engine
The 2007 Cummins 6.7L is the engine’s first year, which means it has a lot of problems. It’s unreliable and has many other issues that make it not worth buying.
The engine itself isn’t very efficient, so this will cost you more money in fuel than most other engines.
Reasons To Avoid
The above issues are present in the 2007 6.7 Cummins engine, but there are also a few more that this first model had.
This includes fuel dilution problems and a general difficulty getting parts, as this is the first model to include the 6.7 Cummins engine.
Fuel Dilution Problems
Fuel dilution is a common issue many diesel engines face. This is a problem because it can cause damage to critical engine components and parts.
Dilution problems, also known as “puking and kicking,” occur when the fuel filter is clogged, causing fuel to back up in the lines and flood the fuel pump.
3. 2015 6.7 Cummins Cummins Engine
The 2015 6.7 Cummins engine has great power and good fuel economy, but it’s not the most reliable model year. Usually, the problems are minor and easily fixed, but there are some significant issues to be aware of.
Reasons To Avoid
Besides the above issues, your 2015 may be more likely to encounter the following:
- Fuel system problems
- EGR valve issues
- Cooling system issues
Again, there are all fixable, but they can cost a lot of money and time if you encounter them.
Fuel System Problems
Another big issue among owners involves fuel filters failing prematurely, often within the first 50k miles (80,467 km)! This problem seems to be especially acute with diesel during cold weather.
Still, it can occur at any time throughout the year due to other factors such as improper maintenance or driving conditions (i.e., lots of stop-and-go driving).
EGR Valve Issues
The EGR valve sends exhaust fumes back to your engine. If it malfunctions, your emissions could run high, which will end up costing you a lot in repairs and fines. Your Cummins truck engine may have other issues that cause problems with the EGR valve.
For example, suppose your turbocharger isn’t spinning freely or delivering adequate boost pressure to the engine. In that case, you can cause debris to get sucked into the EGR valve. This wears out your components faster and can result in an expensive repair.
Cooling System Issues
A common complaint among owners of this truck is that the cooling system seems a little finicky. Some owners report having trouble getting their trucks up to temperature on hot days. In contrast, others say they never had any problem with their cooling systems.
It’s not clear if there is something specific about this model year that makes them more prone to overheating or if it just runs hotter than older models because of technological advancements.
4. 2014 6.7 Cummins Engine
2014 6.7 Cummins has had many issues. The oil consumption issues have come up, as well as turbocharger issues and head gasket problems.
Injector issues are also common in this year’s model, so if you’re looking at buying a used 2014 Cummins, keep an eye out for the warning signs of wear and tear and pay special attention to the mileage.
Reasons To Avoid
The above issues are likely to plight your 2014, with the addition of a possible “death wobble” appearance. It often occurs in Jeeps and Trucks if you’ve never heard of this. Diesel engines are notoriously susceptible to it, too.
The Death Wobble
A death wobble occurs when your steering wheel starts shaking violently while driving on rough roads or uneven terrain, especially at speeds over 60 mph (100 km/h). If this occurs, you’ll need to bring your car into the shop immediately!
The 6.7 Cummins Engine Explained
The 6.7 Cummins is a very popular engine for Dodge trucks and Ram trucks, but there are some years that you should avoid if you’re looking to buy a used truck with this engine.
There are also specific issues to look out for when buying a used 6.7 diesel truck. There have even been issues with the 2023 models, causing a recall!
The 6.7 Cummins engine was first introduced in 2007. Aside from the larger displacement, it was also the first diesel engine to have a turbocharger and a diesel particulate filter.
It has a reputation for being one of the most durable, efficient, and powerful engines ever made by Cummins. The 6.7 Cummins has been used in many applications such as buses, trucks, cars, and farm equipment like combines.
The first thing to know about the 6.7 Cummins is that it is one of the most complicated engines on the market, even more so than other diesels like Ford’s Power Stroke or GMC’s Duramax diesel engines.
The number of sensors and solenoids that control everything from fuel delivery to emissions makes them especially hard to work on as well; in fact, there are only two shops in all of North America that specialize in repair work for these engines (one in Detroit Michigan, one in South Carolina).
If you have any problems with your truck, especially leaks or clunks from the drivetrain or transmission, it’ll be nearly impossible (and very expensive) to find someone who can fix it unless they specialize specifically in these types of repairs.
The other thing to know about the 6.7 Cummins is that it has a lot of problems with premature wear and failure. This is because of how complex these engines are; they use so many sensors and solenoids that they can also cause problems if something goes wrong with one of them.
When this happens, it causes an issue in how the engine operates, which leads to more problems down the road.
Final Thoughts
The 6.7 Cummins is an incredible engine that has proven itself repeatedly as one of the most durable engines ever built. It can pull heavy loads and be easily modified to make it even more powerful.
However, some years should be avoided because they have a higher risk of failure due to design issues or poor quality control during production.
