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What Is The Life Expectancy Of A DD15 Engine?

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We know what you could be thinking. A truck lasting you for 60-plus years is unheard of and quite frankly impossible. But we are talking about semi-trucks, and the average mileage of these vehicles is roughly 45,000 miles per year.

So, with the average lifespan of DD15 engines in consideration, this gives you approximately 22 years of usage before the need for major repairs or the engine gives up. 

The DD15 engine is rated at a million B50 life. This stands for a million miles, while the 50 is for 50% of all production model engines, meaning 50% of all produced DD15 engines will at least reach a million miles before requiring any significant repairs or overhaul. The B-life rating is the industry standard for projecting the supposed life expectancy of an engine. 

That is why it is common for the odometers on these vehicles to read in the high hundred thousand and even millions. It is because of the type of usage required of them. 

Trucks with these engines bring essential cargo like food, water, and other necessary equipment used every day all over the country. Some of them travel locally, while some travel cross-country. 

This is why an engine like a DD15 was invented. It's designed to take on a ton of mileage for longer use. Machines like these were built to take on the abuse of everyday driving while hauling tons of cargo and at the same time cover long distances to deliver whatever they need to deliver.  

Brief History of the DD15

The DD in DD15 stands for Detroit Diesel, an American engine manufacturing company from Detroit, Michigan. Founded by General Motors in 1938 and is currently owned by Daimler Truck AG, one of the largest vehicle manufacturing companies in the world.

Detroit is dubbed "Motor City, "as great American car brands like Ford, Dodge, GM, and Chrysler were born here. Detroit is also considered the cradle of the automotive industry and the capital of the automotive age, only making the reputation of the DD engines all the better. 

Specs of the DD15 engine

A huge Daimler truck moving on the highway

The new 5th generation DD15 engine is one of the most popular choices of engines for class 8 trucks. The engine is EPA 07 compliant and can pass EPA 10, making it one of the best engines for emission standards. Below are some of the most notable specs for the engine. 

  • Inline 6 Cylinder
  • Displacement 906 cu. in. [14.8 L]
  • Compression Ratio [18.4:1]
  • Bore 5.47 in. [139 mm]
  • Stroke 6.42 in. [163 mm]
  • Weight [Dry] 2763 lb. 
  • Electronics [DDEC]
  • Oil Capacity 45.5 qt. [43 L]
  • 455 hp-505 hp
  • 1550-1750 lb-ft of torque

The cost of replacing a DD15 may vary depending on your location and the shop or mechanic that will be doing it. Some trucking companies have their mechanics do this for them, especially if they have a fleet of semi-trucks that needs regular maintenance to operate them properly.

But in most instances, the ballpark figure that you can expect is somewhere around $4000 in labor alone. This is because usually, it may take up to 40-hours of labor and a per hour rate of $100. You can also expect to pay $500-$1000, or even more for parts exchange. This already includes warranty costs. 

Freightliners lined up at trucking industry

The DD15 is one of the most reliable diesel engines ever made. 

Detroit Diesel uses an Amplified Common Rail Fuel System [ACRS] paired with DDEC IV electronics. This creates an optimal combustion system giving you the right timing for torque release in the engine.

The combustion ratio of 18:41 also helps in the cylinder pressure, thus resulting in less strain on the engine than in other designs. This also allows more power output and responsiveness. 

Maintenance is also made easier and cheaper. The overall design of the engine allows it to have longer intervals in between servicing. Its parts are also simplified, such as having its oil filters on the top of its frame rails with a cartridge for easier replacement.

Coupled with more than eight decades of experience in motor engines, Detroit Diesel has already proven that it makes quality and trusted Diesel engines that are powerful and reliable and can stand the test of time. 

But like all engines, no matter how reliable they are, DD15 engines still experience problems in some of their production engines. Some issues include oil leaks, crankcase breather problems, and low oil pressure. But these problems are easily solvable and are most likely not to happen to you, especially if you are on top of your maintenance. 

The new 5th gen DD15 is currently available for Freightliner Cascadia and Western Star 49X trucks. Paired with DD's DT12 automated manual transmission, coupled with Detroit Axles and Detroit Assurance 5.0 Suite of Safety Systems. The engine also boasts an industry-leading fuel efficiency rating. 

Is it cheaper to rebuild or replace an engine?

Mitsubishi Fuso truck using a DD 15 engine

Rebuilding or overhauling an engine is done after seeing a ton of mileage. This is more so on diesel engine trucks like the DD15, which is subjected to long miles. 

Overhauling is the adjustment or the makeover of your engine to improve performance, boost its power, and extend its durability. It is also done to improve the fuel economy of your engine. This process tries to revive your engine to make it run like brand new again. 

Usually, having your engine overhauled is cheaper than getting it entirely replaced. But in some instances, having it rebuilt may not be enough to save the engine. It can even cause you as equal or even more compared to buying a new one, so it is crucial to have a mechanic that will be upfront and honest with you to do the diagnosis and estimate on your engine. 

A trusted mechanic can also make a difference between having your engine run like new or making it even worse. An engine overhaul is relatively technical and requires expertise to do such procedures on your engine. 

In an engine overhaul, these are usually the parts that are replaced or repaired. These parts are the ones that are more active, meaning these are either moving parts or subjected to temperature changes when the engine is running. You can also find these parts in most overhaul kits. 

  • Cylinder head hardware
  • Thermostats
  • Oil-pressure regulator
  • Connecting rod
  • Pistons
  • Gaskets
  • Rings
  • Skirts
  • Pins
  • EGR valve
  • Valve-train components
  • Connecting rod

The cost of having an engine rebuilt will vary depending on your location, parts needed, labor,  the type of class your truck is in, and the services that you employ. But you can expect a guesstimate figure of anywhere between $20,000-$40,000.

It is noteworthy that some shops may accept that you provide your overhaul kit, while some don't, the reason for this is quality control. Some repair centers will only warrant parts they supply as they claim that this will ensure that the parts used will be of quality. 

A long line up of Daimler trucks

If you choose the more expensive route to replace your entire engine, you can expect to pay $40,000-$50,000, and possibly even higher. Again, prices may vary and depend on the variables stated above. 

This is why it is essential to do proper consulting and, if possible, have multiple shops or repair centers to choose from, so you can choose which one will be the cheaper option without compromising work quality. 

Regular maintenance such as an oil change and routine checkups are imperative to help make your truck or any vehicle last long, especially with an engine like a DD15, which was already designed to go a long way. This will make sure that you maximize the potential of your engine and ensure safety and comfort while driving. 

In review

Two freightliner trucks parked at a dealership

The DD15 engine is one of the most reliable diesel engines available in the market. It can easily give you a million miles as these engines were purposely designed and built to run such heavy mileage. 

The simplicity of the engine's design makes it easy to work and do maintenance on. The DD15 continues to be one of the industry standards for durability and reliability, a true testament to American automotive genius. 

Below are some related articles that we have previously written just for you. Go ahead and check them out to learn more. 

Diesel Engine Won't Start In Cold—What Could Be Wrong?

Are Car Engines Waterproof? [A Look At Gas And Diesel Engines]

How Many Miles Does A Semi Truck Last?