The Most Common 6.7 Cummins Problems

Thirty years ago, in 1989, Dodge and Cummins made the inseparable duo that became a force to reckon with. It started with the Cummins 5.9, and following multiple iterations, the Cummins 6.7 became the diesel engine of choice for the Ram pickup trucks. So if you’re looking for a lot of power and torque (up to 1000+ lb-ft) from an engine that doesn’t guzzle too much diesel, in a package that looks great and drives well, it’s hard to wonder why anyone would want to look elsewhere. But the Cummins 6.7, although one of the best engines out there, isn’t exactly problem-free. Let’s take a look at the common problems and we’ll offer some possible solutions to help you make your 6.7 Cummins ownership a lasting, happy experience.

Common 6.7 Cummins Problems and Issues:

1. Clogged turbocharger
2. EGR and DPF issues
3. Exhaust troubles
4. Usual check-engine light
5. Head gasket failures
6. Injectors going bad

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Clogged Turbocharger

As Ram moved from the 5.9 Cummins to the 6.7 Cummins, a lot of important components got updated. Among these improvements was the turbocharger. On the 6.7 Cummins, there’s a variable-geometry-turbine turbocharger. It reduces the turbo lag and hence makes the truck easy to drive. Another development was with the turbo/exhaust brake. This made driving the truck while towing a lot less taxing on the brakes.

If you’ve got a faulty turbocharger or turbo actuator, you can be looking at reduced performance and added strain on the engine. The issue with the turbocharger failure was blamed on the presence of emission control devices, EGR in particular. This made the air that goes into the turbocharger dirtier, which would cause the turbocharger to clog.

Obviously, this isn’t the best position to be in since the 6.7 Cummins is a decently powerful truck — even in its early specs. Without a properly functioning turbocharger, both the performance and longevity of the vehicle will be reduced. The replacement turbochargers are generally updated, and therefore don’t face the issue.

Our pick for the best turbo for 6.7 Cummins is the BuyAutoParts Turbo Kit.

If you want to learn more about it or the other ones in our top 5, click here.

EGR and DPF issues

The 6.7 Cummins replaced an engine known for its decent reliability, an engine that helped a lot of truck owners go the diesel route, an engine that could work day in and day out without breaking a sweat. It was the 5.9 Cummins, used in Dodge Ram trucks from the time Cummins and Dodge collaborated in 1989. In 2007, when the 6.7 Cummins was introduced, it was faced with the challenge of being a more “modern” engine while also handling everything as well as the 5.9 Cummins. It met the challenge of living up to the legacy of the 5.9 Cummins, but there was a small issue. To be a “modern” engine, the 6.7 Cummins was designed with a lot of emission equipment like the Exhaust Gas Recirculation and Diesel Particulate Filter to reduce the truck’s pollution. 

Due to the complication in the system, the 6.7 Cummins ran into a few problems. One of the problems was clogged turbochargers, which was a direct result of using EGR, which we’ve just previously mentioned. Other issues involved a decrease in performance. A failed/blocked DPF, for instance, can mean a loss in power, bad smells from the engine, and even a substantial drop in the fuel economy. This happens when the DPF can’t undergo regeneration — and that can be because of short journeys where the engine can’t attain optimal temps, incorrect engine oil, too much fuel, or even a clogged EGR valve, among other things.

To address that, third-party manufacturers came up with delete kits. Depending on the kit, you can remove the DEF (Diesel Exhaust Fluid) or the SCR system (Selective Catalytic Reduction). By doing so, you’ll allow the engine to run at cooler temperatures and not run into EGR issues, among other problems. But you also need to understand that using a delete kit on a truck for public-road use is illegal. If you’re participating in competition events/racing, then DPF removal won’t be a problem.

If you’re looking for a delete kit, we recommend the Sinister Diesel Kit.

You can read more about it and the other top two delete kits for 6.7 Cummins by clicking here.

Exhaust troubles

The thing with the 6.7 Cummins is that it’s a hugely capable engine. From daily use to regularly towing heavy loads, it won’t disappoint. And that’s why most Ram trucks with this engine are reliable workhorses — handling everything with ease. Hook up a fifth wheel, do a cross-country drive, come back home battling rush-hour traffic, and the truck won’t break a sweat. As you keep driving, though it does take a toll on certain components. One of the problems that owners and enthusiasts are aware of is the exhaust manifold losing its shape.

This is because of the excessive heat that it has to withstand throughout its life. The solution to this is fairly simple. You take the existing part out and replace it with an aftermarket manifold. Some of these tend to last longer than the stock part, and so spending a little extra on this makes sense.

And while you’re looking at the exhaust manifold, you can also check out our selection of the aftermarket exhausts available for 6.7 Cummins by clicking here. Our top pick is the MVP Performance Race 4″ Turbo Back.

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And the Usual Check-Engine Light

The 6.7 Cummins is a very popular engine among enthusiasts as well, always trying to improve their truck with the best upgrades. And while this does generally bring improved performance, it may also sometimes throw up an error code on the dashboard. This is a common issue in trucks with upgrades since it’s not because something has failed but because the onboard computer hasn’t been able to register the presence of a new part.

To solve this issue, it’s recommended to get a tuner for the 6.7 Cummins. Tuners come in various shapes and forms: you can either get a handheld device or look for a more comprehensive tuner+monitor combination that allows you to check in real-time how well your truck is performing. The tuner also usually comes with a variety of tunes, and depending on your use, you can choose the engine tune and enable the truck to perform more efficiently in the way you’d like. For instance, if you’re towing, you can choose the towing tune and then enable the truck to deliver its power in a way that’s best for towing.

With a tuner, not only can you check what’s going wrong or update the truck for new parts, but you can also check and clear error codes. You can take a look at the popular choices for the best tuner for 6.7 Cummins by clicking here. We think Edge Products’ Juice with Attitude CTS2 is the top choice. 

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Other Common Failures on the Cummins 6.7

Despite the previously mentioned problems, the Cummins 6.7 is still one of the most popular and trustworthy diesel engines on the market. That’s because these problems can be solved, and won’t get in way of you enjoying the truck. But like most other modern diesel engines, the 6.7 Cummins also has a few other issues including head gasket failures and injectors going bad.

For the head gasket failures, it can be down to increased performance with aftermarket parts that take a toll on the engine, among other causes. Since the engine is such a workhorse most owners put it to work day in and day out. Head gaskets can fail because they’re overworked. The solution to this is to use a better cylinder head to engine block fastener.

The injectors, on the other hand, are like on any other diesel engine. The 6.7 Cummins has a high-pressure-common-rail system that sends fuel to the engine. The system works better and faster than previous systems. This also means the injectors tend to eventually wear out. Replacing the injectors is the way to fix it.

What Problems Does the 6.7 Cummins Have?

The 6.7 Cummins is a great engine and thankfully it’s not plagued with issues. The ones mentioned here are mostly either due to extra load or regular wear. But there must be a way to keep these at bay, right?

It depends on the issue at hand. Let’s start with the turbocharger problems. If you’re running one of the early trucks, there’s a solid chance that you’ve gotten a replacement already. The turbochargers that Dodge replaced as a part of their recall/update were reported to be free from the issue of getting clogged because of the EGR. In case you’re looking at picking up a used Dodge Ram truck with the 6.7 Cummins engine, keep in mind that the replacement turbochargers generally last very long, so you probably won’t have to deal with the issue again. It’s possible to get a power increase by installing a different turbocharger, but that has its negatives — like overburdening other components. Upgrades have to be done while keeping in mind the overall power increase and how that directly affects the other parts.

EGR and DPF deletes can help get some slight improvement in performance without having to spend on other upgrades. But this does affect the environment, and your truck won’t pass emission tests. So these make sense only if you’re driving just at the track or in competition events. For public-road use, it’s not recommended (and usually illegal) to get EGR and DPF deletes. Things like longer engine life and massive power boosts by implementing a delete aren’t always for sure. DPFs are less likely to die on you earlier than 100,000 miles. As routine maintenance, changing the components might ask you to spend more than normal. But on the other hand, if the truck isn’t showing the usual signs of failure related to emission control equipment, you can let it be. Consulting a mechanic is a good choice in this case.

Parts like injectors will eventually require a replacement after you reach a certain mileage. That’s a bigger expense on modern engines but the part has to keep performing the important task of getting fuel to the combustion chamber, so spend wisely. It’s a similar story for head gaskets as well. The exhaust manifold is one of the other issues. Now for that, it’s not going to break the bank but will ensure the engine runs optimally without letting heavy loads cause harm to it.

Tuners are a good way of managing the truck’s performance. And that works well with the 6.7 Cummins. Our suggestion is to refrain from the extreme tunes. Because even though the power increase seems too good to not use it, it’ll increase the stress on existing components, wearing them out much faster. Tuners can also detect and clear engine error codes. And for a modern truck, that’s a plus. So say you’ve got a new air intake but you aren’t sure if the engine is performing well or not. A tuner, in this case, will be able to check for errors and allow you to clear the warning as well. Real-time monitoring can be extremely useful to those who love to mod their trucks regularly.

Ways to Keep the Problems at Bay: Tips for Maintenance

[If you want more details and product recommendations on maintenance for your RAM truck, please read our Ultimate Maintenance Guide for RAM Trucks.]

If you think there’s something off with your truck, and you’re not confident enough to play mechanic, it makes sense to get a routine check-up of the truck. This will ensure a longer life and hassle-free ownership. In addition to that, certain parts need to be replaced at predefined intervals (specified by the manufacturer).

Unless changed on time (or earlier if they wear out quickly), these can have a domino effect and affect other components as well. For instance, if you don’t change the truck’s brake pads on time, not only will the braking abilities be hampered, soon after these go bad, the rotors will begin to deteriorate very quickly.

Another example can be of cold air intakes: if the filter is due for a replacement or if the intake itself has an issue, it can harm the engine in serious, irreversible ways. The same can be said about the fuel filter on the 6.7 Cummins. Dirty fuel and water both can ruin the engine, so it’s absolutely necessary that the fuel filter is changed on time as well.