While the 6.7 Cummins turbo-diesel is one of the best modern power plants on the market, it is far from a perfect engine. Unfortunately, one of the biggest issues is the Holset HE351VE turbocharger and VGT actuator failure.
When the actuator fails you will run into a number of performance related issues like a loss of power, smoke from the turbo, and high EGTs which can lead to serious engine damage. In this guide we’re going to cover all the signs and symptoms of VGT actuator failure, the reasons they fail, and discuss how to diagnose and fix these issues on the 6.7 Cummins.
VGT Turbo Basics
Since Dodge/Ram began using the 6.7 Cummins as the replacement to the 24-valve 5.9 Cummins in 2007, it has always used the same Holset HE351VE “Variable Geometry Turbocharger” (VGT). VGT turbochargers have been around since the late-1990s, but have become much more common over the last decade-and-a-half. These turbos contrast with fixed geometry turbochargers, which are standard in most non-diesel applications.
VGT blowers are designed to function similar to that of a twin-turbo system. The idea is that VGTs are responsive enough on the low-end to give a quick boost response, while also being capable of running large amounts of boost to make power on the top-end. Essentially, it’s the best of both worlds: The response of a small turbo but horsepower capabilities of a big-turbo, or a big-turbo without the lag — whichever you prefer.
VGTs work by varying the size of the exhaust housing on the turbo. The larger the exhaust housing the more air the turbo will take in, equating to more power. On the flip side, the smaller the exhaust housing the quicker response and less lag. VGTs use a steel ring and vanes that control the exhaust housing size, allowing it to shift from small to big depending on the need.
This steel ring is controlled by what is known as a “VGT actuator.”
What is a Turbo Actuator?
So what exactly is a Cummins VGT Actuator? The VGT actuator is the piece of equipment that controls the positioning of the steel ring and vanes inside the turbo. It takes input from the engine’s ECU to determine how much boost is needed, and moves the steel ring and vanes to compensate.
Basically, when the engine is at low-load, the actuator forces the vanes to be as close to the turbine wheel as possible, reducing the size of the exhaust housing. At higher loads, the vanes start to separate from the wheel, allowing for more exhaust to enter and spin the turbine wheel faster. The Actuator is a mechanical piece of equipment that physically alters the position of the steel ring and vanes. However, the actuator is controlled through an electronic solenoid.
6.7 Cummins VGT Actuator Failure Symptoms
- Check Engine Light for Turbocharger (Often P2262)
- Excessive Smoke From Turbo
- High Exhaust Gas Temperature (EGT)
- Loss of Power at Low RPM
- Loss of Power at High RPM
- Loss of Engine Brake or Full-time Exhaust Braking
Chances are, if you are experiencing Cummins VGT actuator failure, you will likely know pretty quickly. One of the most obvious symptoms is a check engine light, which is often the P2262 on the Rams. There are several other CEL codes that come up, most of them relating to the turbocharger and overboosting or communicating with the ECU.
Another pretty obvious sign is excessive smoke coming from the turbo. This can happen from excessive soot/carbon burning after gluing up the inside of the turbo and causing actuator failure. If you have an EGT gauge you are monitoring, you will also likely see a spike in EGT with VGT actuator problems.
A huge tell-tale indicator is the loss of the engine brake. The 6.7 Cummins has an engine brake through the VGT, which will stop working if the actuator fails. Alternatively, it might stay activated all the time even under acceleration if there is a problem. If you don’t use the exhaust brake you might not notice this, but for those who do it’ll be pretty obvious pretty quickly.
Finally, depending on where the steel ring and vanes are when the actuator fails, you might experience problems at either higher or lower-RPMs. If the actuator is stuck close to the turbine, you’ll likely struggle to make sufficient boost on the top-end. On the other side, if the actuator is far away from the turbine, the turbo will struggle to build any boost at all from a stop.
Electrical vs Mechanical Actuator Diagnosis
As we mentioned earlier, the Cumins VGT actuator is a mechanical piece of equipment that is electronically controlled. This means you can have either a mechanical or electrical failure of the actuator. If it’s electrical failure, replacing the electronic guts can sometimes solve the problem. However, it’s a mechanical problem, you will need a new actuator and sometimes even a new turbocharger.
Mechanically, the most common cause of Cummins VGT actuator failure is excessive soot or carbon buildup. The actuator can become too caked in gunk to function properly, causing it to fail mechanically and no longer actuate the steel ring and vanes. Additionally, if the steel rings and vanes themselves become seized with gunk, it can cause the actuator motor to overheat and fail from trying to move them.
Electronically, the actuator itself can fail, either from bad/broken wiring or just outright. This is probably the most common cause of actuator failure on the Cummins. If the actuator electronically fails, the steel ring and vanes will be stuck in whichever position they were last in, causing the top/low-end problems we went into above.
VGT Actuator vs Vane Failure Diagnosis
Speaking of potential steel ring and vane failure, it’s important to determine what the actual problem is before going any further. If the steel ring and vane are seized but the actuator is fine, replacing the actuator won’t solve the problem. Likewise, if the actuator has failed, replacing or cleaning the steel ring and vanes will not do anything.
The folks at CityDiesel in Decatur have a good guide for checking the vanes on the Holset turbo. Basically, you move the vanes by hand to make sure they are in working order and to verify the problem is with the actuator.
What Causes VGT Actuator Failure?
So what is the cause of Cummins VGT actuator failure? The most common cause is a buildup of carbon, soot, rust, and corrosion in the turbine housing. This either causes the steel ring and vanes to seize up, or the actuator to mechanically seize up. If the steel rings and vanes seize, it can also cause the motor to overheat and fail. Due to the 6.7 Cummins use of an exhaust gas recirculation (EGR) system, even more soot and carbon can build-up in the turbo’s turbine housing than other engines.
Electronically, the actuator can fail either from overheating, bad wiring, or just due to faulty components. If the actuator electronically fails, it will not be able to mechanically function, which can lead to even further turbo damage.
Most Cummins owners do not realize, but the VGT actuator is actually required to be cleaned at specific intervals. This is to get rid of the accumulation of soot and carbon inside the turbine housing and actuator. Unfortunately, many owners ignore this cleaning interval at their own peril, which can eventually lead to failure.
How Do I Fix 6.7 Cummins Turbo Actuator Failure?
If you have determined that you do in fact have Cummins VGT actuator failure, you have a few options depending on the failure. If the failure is mechanical, you can always try cleaning the actuator and seeing if that solves the problem. However, most of the time cleaning, if it does help at all, will only temporarily get rid of the issue, and usually it reappears.
If the failure is electronic or deemed too far gone to be cleaned, installing a new actuator is the only fix. Unfortunately, neither Cummins nor Ram sell just the actuator themselves. Finding an OEM replacement on the web is an option, but they are not always available. That means that often, you will need to install a brand new turbocharger with a functioning actuator in order to solve the problem.
This is probably the biggest kick in the pants with 6.7 Cummins turbo actuator failure: the huge cost. If you can clean the actuator and solve the problem it’s a relatively easy and cheap fix, but if you need a new actuator or turbo get ready to pay. An OEM replacement actuator typically runs about $1,400 brand new on the web. There are non-OEM replacements, but considering how important the part is we definitely recommend OEM.
If you need to get a new turbo, you’re looking at a minimum of $2,500 for a brand new turbo or about $1,500 for a remanufactured turbo. You can also go with an upgraded VGT turbo for better performance. Or, if you want to get rid of the hassle forever, you can swap in a non-VGT turbo, though at the expense of the VGT’s superior performance.
How Can I Prevent Failure?
The two biggest things you can do to prevent Cummins VGT actuator failure is to use the exhaust brake as much as possible, and to follow the Cummins’ specified cleaning schedule for the actuator. If you have already experienced failure, it’s probably too late to use either of these, that’s why it’s important to start using them before it’s an issue.
By using the exhaust brake, you are getting rid of the soot and carbon build-up just through the normal function of the engine. It’s an easy switch to turn on when you start the engine, and the hardest part is initially remembering. In addition, by cleaning on schedule, you can remove any soot and carbon before it causes parts to seize.
Overall, the 6.7 Cummins turbo-diesel is a fantastic engine, and the Holset HE351VE VGT turbo offers exceptional performance. However, its known problems with VGT failure are one of the engine and turbo’s biggest drawbacks. Usually, 6.7 Cummins turbo actuator problems stem from excessive soot and carbon build up, which can be eliminated by regularly using the exhaust brake and through regular cleaning of the turbo.
If you do run into a problem with the actuator, you can either replace the actuator or the entire turbocharger, both of which are very expensive. At that point, you might even consider upgrading to a bigger turbo with increased performance over stock.
While 6.7 Cummins VGT failure is certainly an issue, the 6.7 Cummins is still an incredible engine. Hopefully, Cummins will decide to swap in a better actuator in the future (they’ve tried before and failed) that will alleviate the problems on future Rams. But until then, get prepared for an expensive and timely fix.
Frequently Asked Questions
The biggest symptoms of a faulty Cummins VGT actuator are loss of engine brake, full-time engine braking even under acceleration, P2262 check engine light, and a lack of throttle response. Usually, a failed actuator will require the replacement of the entire turbocharger.
The most common cause of VGT actuator motor failure is excessive carbon and soot build up in the turbine housing. This can cause the turbo to seize and the motor to fail.
If a VGT turbo actuator fails the VGT turbo will fail to control and optimize boost pressure, resulting in poor performance and response. It can also cause the loss of the engine brake in the 6.7 Cummins.
A Cummins VGT actuator is a part of the VGT turbo. The actuator controls how much boost the VGT makes and how responsive it is. A failed actuator means the turbo cannot regulate and optimize boost, resulting in poor performance.