A 6.7 Cummins long block is the core engine without fuel injection, transmission, or external accessories

A long block for a 6.7 Cummins diesel engine includes the cylinder block, pistons, crankshaft, camshaft, cylinder head, and valve train — essentially everything inside the engine case. It does not include the fuel injectors, fuel pump, turbocharger, alternator, water pump, or any other bolt-on parts. You get the engine's internal working pieces, ready to be installed into an engine bay, but you will need to transfer or buy those external components separately.

The 6.7 Cummins is a diesel engine made by Cummins and installed in Dodge Ram trucks from 2007 onward. A long block is typically sold when an engine has internal damage — cracked pistons, bearing wear, cylinder scoring — that makes rebuilding the internals cheaper than replacing the whole engine. It is also used when someone wants to upgrade to a newer or different version of the engine without paying for parts they already own.

Key Takeaways

  • A long block contains the cylinder block, head, pistons, and crankshaft but not the fuel injectors, turbo, or external accessories you will need to move from your old engine.
  • Long blocks are sold as either remanufactured (rebuilt to factory specs by a professional shop) or used (pulled from a salvage vehicle with unknown history).
  • Installation requires removing your old engine, transferring external parts, and having the cooling system and fuel lines reconnected by someone with diesel engine experience.
  • A remanufactured long block typically comes with a warranty of one to three years, while used long blocks usually carry no warranty or a very short one.
  • Total cost to have a long block installed ranges widely depending on labor rates in your area and which external parts need replacement.

Remanufactured versus used long blocks

A remanufactured long block has been disassembled, inspected, and rebuilt to factory specifications by a professional engine shop. The internal parts are either restored or replaced, and the block is tested before sale. Remanufactured blocks come from shops that specialize in diesel engines and typically carry a warranty — often one to three years depending on the shop and whether you install it yourself or have a dealer do it.

A used long block comes from a salvage yard or a vehicle that was totaled or scrapped. You do not know how many miles it has, how it was maintained, or whether internal damage is already present. Used long blocks are much cheaper upfront but carry little to no warranty. Some salvage yards will offer a short may provide (30 to 90 days) that the engine will turn over and hold oil pressure, but that is not the same as a may provide that it will last.

The choice between the two depends on your budget and risk tolerance. A remanufactured block costs more but gives you predictability. A used block is a gamble — you might get thousands of miles out of it, or it might fail within months.

What you need to transfer from your old engine

When you install a long block, you are keeping the external parts from your current engine and bolting them onto the new block. This includes the turbocharger, fuel injectors, fuel pump, alternator, water pump, power steering pump, air compressor (if your truck has one), and all brackets and sensors attached to the outside of the block.

Some of these parts may be worn or near the end of their service life. If your water pump has 200,000 miles on it, it may fail shortly after you install the new engine. Many shops recommend replacing the water pump, fuel filter, and fuel pump while the engine is out, since you have access and labor is already being paid. Gaskets and seals that sit between the block and these external parts will need to be replaced during installation.

You will also need to drain and flush the cooling system before reconnecting it to the new block, and you may need new hoses if the old ones are cracked or brittle.

Installation labor and what to expect

Installing a long block is not a backyard job for most people. The engine must be lifted out of the truck using a hoist, all hoses and electrical connections disconnected, the transmission separated from the old engine, and the old block removed. The new long block then goes through the reverse process: bolted to the transmission, all external parts transferred and bolted on, hoses reconnected, electrical connections restored, and the cooling system refilled and bled of air.

A diesel shop or a Dodge dealership will charge labor time for this work. Labor rates vary by region and shop, but engine replacement typically takes 15 to 25 hours. At a shop charging $100 to $150 per hour, that is $1,500 to $3,750 in labor alone. A dealership may charge more. Some independent shops may charge less, but you want someone experienced with the 6.7 Cummins specifically, not a general mechanic.

The job usually takes three to five business days if parts are in stock and no complications arise. Complications — such as a seized bolt, a cracked coolant line, or a sensor that needs replacement — can add days and cost.

Total cost and whether a long block makes financial sense

A remanufactured 6.7 Cummins long block typically costs $2,500 to $4,500 depending on the year and source. A used long block might be $1,200 to $2,500. Labor to install it runs $1,500 to $3,750. Gaskets, seals, coolant, and other consumables add another $300 to $800. A new water pump, if you choose to replace it, adds $200 to $400.

Total cost for a remanufactured long block installation is often $4,500 to $9,000. A used long block installation might be $3,000 to $6,500. A complete new engine (short block plus all external parts already installed) costs $5,000 to $8,000 before labor, and labor to install a complete engine is similar.

Whether a long block makes sense depends on the condition of your external parts. If your turbo, fuel injectors, and alternator are in good shape and have relatively low miles, a long block saves money. If those parts are also worn, you may be better off with a complete remanufactured engine or a used complete engine, since you will not have to transfer anything and the labor is the same.

Warranty and what it actually covers

A remanufactured long block warranty typically covers internal engine defects — cracked blocks, bearing failure, piston damage — for the warranty period. It does not cover external parts you transferred from your old engine, damage from improper installation, or damage from running the engine without oil or coolant.

Some warranties are voided if you install the engine yourself or if you use a shop that is not on the remanufacturer's approved list. Read the warranty document before you buy, and ask the shop or seller what happens if the engine fails at 18 months — do they rebuild it, replace it, or refund your money.

Used long blocks usually come with a 30 to 90 day "as-is" warranty, meaning the seller will take it back if it does not run at all, but will not cover failure after that period. Some salvage yards offer no warranty at all.

Alternatives if a long block does not fit your situation

If the cost of a long block plus labor is close to the cost of a complete remanufactured engine, a complete engine may be the better choice. You avoid the labor of transferring external parts, and you get a warranty on the whole unit rather than just the internals.

If your truck is older or has very high miles, you might also consider whether engine replacement makes financial sense at all. If the truck is worth $8,000 and you are spending $6,000 on an engine, you have less margin for other repairs. A mechanic who knows your truck can help you think through whether the investment is worth it.

Some people also choose to have their current engine rebuilt in place rather than replaced. This is slower (the truck is down for weeks) but can be cheaper if the damage is limited to one area, such as a single cylinder or the fuel injection system.

Frequently Asked Questions

Can I install a 6.7 Cummins long block in a truck that originally had a different engine?

Not without significant modification. The 6.7 Cummins is designed for specific Dodge Ram models from 2007 onward. Engine mounts, transmission connections, cooling system, fuel lines, and electrical harnesses are all specific to those trucks. Swapping into a different vehicle requires custom fabrication and is beyond the scope of a long block installation.

What year 6.7 Cummins long blocks are interchangeable?

Long blocks from 2007 to 2012 are generally interchangeable with each other, and 2013 to 2018 models are interchangeable with each other. The 2019 and newer engines have different internal designs and are not compatible with earlier years. Always confirm the year of the long block matches your truck's generation.

Do I need to reprogram the truck's computer after installing a long block?

No. The long block is the mechanical part only. Your truck's computer controls fuel injection, emissions, and performance, and it does not need to be reprogrammed for a long block swap. If you are installing a long block from a different year, the computer may need to be checked to may support it communicates correctly with the fuel injectors, but this is usually not necessary if the years are close.

How long does a remanufactured long block typically last?

A properly installed and maintained remanufactured long block should last as long as the original engine — typically 200,000 to 300,000 miles or more. The warranty period (usually one to three years) is not the lifespan; it is the period during which the remanufacturer will stand behind the work. Longevity depends on oil changes, coolant maintenance, and how the truck is driven.

What happens if the long block fails during the warranty period?

Contact the remanufacturer or the shop that sold it and describe the failure. If it is an internal defect covered by the warranty, they will either rebuild the engine, replace it, or refund your money, depending on the warranty terms. You will likely need to pay for removal and reinstallation labor, which is not always covered by the warranty.