6.7-liter Cummins is a turbo diesel engine for super duty Dodge and RAM 2500 and 3500 and provides optimized 1075 lb-feet torque and 400 hp. Many people complain about its few variants because they have significant problems.
What Year 6.7 Cummins to Avoid? It is better to avoid 2007, 2008, 2011, 2014, and 2015 6.7 Cummins engines because they have malfunctioning turbo, clogged Diesel particulate filers, damaged EGR cooling system, poor performance under load, cracked head gaskets, altered fuel composition, and electrical circuit variability.
I avoid a few variants of this engine because they do not provide optimized efficiency due to internal or surface defects. The reduced efficiency decreases their performance which affects the functionality of the truck.
Which year 6.7 Cummins to avoid?
Dodge RAM manufacturers launched the high-performance 6.7-liter Cummins engine in the super-duty variants. However, the engine has a direct fuel injection system, provides high horsepower, and is turbo diesel.
A few variants are not reliable because they have different issues. Its 2007 variants have reduced reliability because its steering system has minimum stability.
You cannot stabilize the steering wheel at high speeds because it reduces the axle performance. Low power flow, motor damages, frequent warning lights, and oil leaks are significant problems of this engine.
This variant undergoes internal cracks and variable voltage defects. It is challenging to start this motor due to its internal damage.
Also, the 2007 variants of this engine have defects in the exhaust gas reticulation system. Its Diesel particulates filter malfunctions and reduce the engine efficiency.
The dilution of fuel is a significant problem for this motor, reducing its efficiency. Its 2008 variants have similar defects to the 2007 engine.
It has electrical problems, emission defects, and reduced steering wheel efficiency. Furthermore, 2011 6.7 Cummins has issues with diesel particulate filters and motor failures.
It’s head gaskets cracks and increases the oil leaks. It affects the internal lubricant, and friction can damage the spinning parts of the motor.
The 2014 variants of 6.7-liter Cummins cannot provide stable efficiency because it has turbocharger defects. Its head gaskets fail, and oil flows out from the system.
It has significant injection system defects and internal damages, which reduces the truck’s mileage. You can avoid its 2014 year because it causes vibrations during high-speed driving.
It is susceptible to motor idling and excessive frame shaking, which causes dangerous accidents. Furthermore, you cannot select its 2015 variant because it has reduced fuel efficiency.
It is not a reliable engine because its exhaust gas reticulation system fails. As a result, it increases the emission of gases and affects the exhaust system.
Also, its fuel system has reduced stability which leads to cooling defects. You can avoid its 2015 variant because its fuel system malfunctions at high speeds.
Its fuel injectors cannot provide enough fuel for optimized acceleration.
Why would you avoid 6.7 Cummins years?
I avoid 6.7-liter Cummins engines because they can undergo sudden failures. You cannot select them due to the mentioned reasons.
One of the most significant issues of a few 6.7-liter Cummins is malfunctioning turbo. The turbo is a specific motor that regulates the compressed exhaust gases and reverses their flow toward the engine.
The turbo malfunctions and cannot stabilize the motor efficiency. Furthermore, its failure can increase the number of broken seals.
The seals break, and oil flows out, which reduces the performance of the built-in bearings and variable geometry turbocharger. The malfunctioning turbo cannot stabilize the motor performance.
Furthermore, the torque reduces when the bearing break. The compressor wheel strikes the turbo and its housing.
It results in turbo failure and motor malfunction. It cannot stabilize the internal temperature. Cold lubricant flows to the seals and breaks them.
Clogged Diesel particulate filters
A few 6.7-liter Dodge RAM Cummins engines have malfunctioning diesel particulate filter clogging. The clogged DPF cannot provide standard efficiency.
Also, the system does not utilize the specific fluid at the optimized level. In such circumstances, diesel soot is a significant problem that causes the clogging of diesel particulate filters.
The issue is prominent in older and less advanced variants of this motor. Moreover, the clogging of DPFs is dangerous because it affects the exhaust efficiency of the pickup truck.
The increased back pressure enhances the pressure over the motor. In such circumstances, the motor malfunctions and cannot provide the horsepower for optimized truck efficiency.
Damaged EGR cooling system
The exhaust gas reticulation system regulates the emission of gases and protects the engine from sudden damage. However, a few variants of 6.7-liter Cummins have significant EGR cooler failures.
The higher number of miles affects the performance of the exhaust cooler and reduces its functionality. In such circumstances, the valve of the EGR system clogs and undergoes several failures.
The EGR and its valve cannot withstand the mileage, and internal pressure increases. The malfunctioning EGR cooling system cannot stabilize the internal Cummins temperature and reduces efficiency.
In such circumstances, the increased emission causes exhaust failure and engine malfunction.
Poor performance under load
A few 6.7-liter Cummins cannot provide stable performance under pressure. You cannot increase the truckload beyond the limitations because it puts excessive pressure on the engine.
In such circumstances, the engine loses its stability and fails. The pistons and camshaft cannot perform at an optimized functionality level.
The mechanical parts break, and emission increases. Also, the exhaust produces more gases and decreases fuel efficiency.
The reduced fuel economy decreases the speed and affects standard mileage. Therefore, you cannot select its few models because they have significant surface and internal defects.
Cracked head gaskets
Head gaskets are seals of 6.7 Cummins combustion cylinders. They provide optimized compression for better stroke and less challenging acceleration.
Furthermore, the head gasket undergoes cracks in a few 6.7-liter Cummins. The pressure of combustion cylinders increases, which cracks these head gaskets.
The seals break, and the oil leaks. Excessive leakage causes engine failures and damages. The engine cannot produce horsepower when the fluid level decreases.
Its motor cannot rotate at the standard torque limits, and efficiency decreases. Altered fuel composition and defective electric circuit
A primary defect of 6.7-liter Cummins is dilution, mixing, and fuel modification. The fuel composition changes when diluted with the internal oil during the engine regeneration procedure.
This motor has a specific fuel injection system. It uses the seventh injector for optimized engine efficiency and fuel flow.
The fuel flows to the exhaust system in this engine during the cylinder strokes. In such circumstances, the fuel and oil mix.
The fuel composition changes due to dilution. As a result, it cannot provide stable performance.
It loses the standard flow properties after the modification. A dilution limit of more than 5% is high and causes several engine defects.
The modified fuel can affect the oil efficiency. It cannot provide motor lubrication and leads to mechanical damage.
Furthermore, circuit variability is a significant problem of these engines.
Their wires lose the connections, and terminals break. Then, the power flow changes, which affects the engine’s performance.
It affects mileage and frame stability, fuel efficiency, and driving comfort.
When does 6.7 Cummins have the most problems?
6.7 Cummins engines have long life expectancies according to their build and specifications. They have an average lifespan of nearly 320000 miles.
However, its variants have significant defects after 130000 miles. Sometimes, the problems appear before 130000 miles because of low maintenance.
Excessive usage can trigger mechanical damage to the engine. In a few conditions, the turbo fails at about 100000 miles and requires a rebuild.
The number of defects increased, which improved mileage. The problems become prominent after 220000 miles on its few variants.
Others have electrical defects after 130000 miles because the electric circuit is susceptible to more damage. Increased load over the pickup truck reduces engine efficiency.
The motor fails and cannot withstand the additional load.