A long block is an engine that includes the cylinder head, but not the external parts
A long block is a partially assembled engine that contains the core components you need to make an engine run, but leaves out the accessories bolted to the outside. It includes the engine block, crankshaft, pistons, connecting rods, cylinder head, valves, and gaskets — everything inside and directly attached to the block itself. What it does not include are the parts you bolt on afterward: the alternator, water pump, power steering pump, air conditioning compressor, intake manifold, exhaust manifold, and fuel injectors.
The distinction matters because you pay for what you get. A long block costs less than a complete engine but requires more work to install. You are buying the expensive, hard-to-machine center of the engine without paying for parts you might already have or might not need for your particular vehicle.
Key Takeaways
- A long block includes the cylinder head and all internal engine parts, but excludes bolt-on accessories like the alternator and water pump.
- Long blocks cost less than complete engines because you are not paying for parts you may already own or can source separately.
- Installing a long block requires transferring your existing accessories from the old engine, which takes several hours of labor.
- A short block (just the cylinder block, crankshaft, and pistons) costs less but requires more reassembly work than a long block.
- Long blocks are most useful when your engine block or cylinder head is damaged but your accessories are still good.
What parts come inside a long block
The long block contains everything that makes compression and combustion happen. This includes the engine block itself (the iron or aluminum casting that holds the cylinders), the crankshaft (which converts the up-and-down motion of the pistons into rotational motion), the pistons and connecting rods (which move up and down inside the cylinders), the cylinder head (which sits on top and contains the valves), the valve train (the camshaft, rocker arms, and valve springs that open and close the valves), and all the gaskets and seals that keep oil and coolant where they belong.
Some long blocks also include the intake and exhaust manifolds, though this varies by supplier. Always confirm with the seller what is and is not included before you buy, because "long block" does not have a single industry standard definition. One supplier's long block might include the manifolds; another's might not.
What you have to add to a long block yourself
After you install the long block in your vehicle, you will need to bolt on the accessories that were on your old engine. These include the alternator (which charges the battery), the water pump (which circulates coolant), the power steering pump, the air conditioning compressor, the fuel injectors, the spark plugs, the ignition coil, the starter motor, and the oil pan. You will also need to reconnect all the hoses, belts, wiring harnesses, and fuel lines.
This is why a long block is cheaper than a complete engine: the supplier did not have to source, test, or install these parts. You are doing that work yourself or paying a mechanic to do it. If your old accessories are worn out or damaged, you will need to replace them anyway, which can add significantly to the total cost of the repair.
Long block versus short block versus complete engine
A short block is even more stripped down than a long block. It includes only the engine block, crankshaft, pistons, and connecting rods. It does not include the cylinder head, valves, or valve train. A short block costs less than a long block but requires you to either reuse your old cylinder head (if it is still good) or buy a new one and assemble it yourself. This is more work and more risk of error.
A complete engine (sometimes called a crate engine or turnkey engine) includes everything: the long block plus all the accessories already bolted on. You can bolt it into your vehicle and connect the hoses and wiring. A complete engine costs the most but requires the least labor to install. The choice between these three depends on your budget, your mechanical skill, and which parts of your old engine are still usable.
| Engine Type | What Is Included | What You Add | Cost Level |
|---|---|---|---|
| Short block | Block, crankshaft, pistons, connecting rods | Cylinder head, valve train, all accessories | Lowest |
| Long block | Short block plus cylinder head and valve train | Alternator, water pump, fuel injectors, manifolds, accessories | Middle |
| Complete engine | Everything assembled and ready to bolt in | Only hoses, belts, and wiring connections | Highest |
When a long block makes sense for your repair
A long block is the right choice when your engine block or cylinder head is cracked, warped, or otherwise damaged beyond repair, but your accessories are still in good working order. If your alternator, water pump, and other bolt-on parts are relatively new or have low mileage, you save money by keeping them and only replacing the core engine. This is common when an engine overheats and warps the head, or when internal damage (like a cracked block) happens but the external parts were not affected.
A long block also makes sense if you are rebuilding an older vehicle and want to use modern engine technology. You can buy a long block from a newer model year and transfer your old accessories to it, giving you a more reliable engine while keeping the original look and feel of your vehicle. This is popular in the classic car and hot rod community.
Labor and installation considerations
Installing a long block is not a quick job. You will need to drain all fluids from the old engine, disconnect the wiring harnesses and hoses, unbolt the engine from its mounts, lift it out, and then reverse the process with the new long block. After the long block is in place, you will need to transfer all the accessories from the old engine to the new one, which can take anywhere from 8 to 20 hours depending on how many parts need to move and how accessible they are.
If you are paying a mechanic, labor costs can easily exceed the cost of the long block itself. Many shops charge $100 to $150 per hour, so a 15-hour job could cost $1,500 to $2,250 in labor alone. This is why some people choose a complete engine instead: the higher upfront cost is offset by lower labor costs. Get a labor estimate from your mechanic before you decide which option to buy.
Where to buy a long block
Long blocks are available from several sources. Salvage yards and used parts suppliers often have them pulled from vehicles that were totaled in accidents or retired from service. These are cheaper but come with unknown history and no warranty. Remanufactured long blocks are rebuilt by specialty shops to like-new condition and usually come with a warranty of 12 months to 3 years. New long blocks from the vehicle manufacturer or aftermarket suppliers cost the most but come with full warranties and may provide quality.
Before you buy, confirm the exact year, make, model, and engine size of your vehicle. Long blocks are not interchangeable across different engine families, and installing the wrong one will not work. Also ask the seller whether the price includes shipping and whether there is a core charge (a deposit you pay upfront and get back when you return your old engine).
Frequently Asked Questions
Can I install a long block myself if I have basic mechanical skills?
It is possible but challenging. You will need an engine hoist, jack stands, and a good repair manual for your specific vehicle. The hardest part is not the installation itself but transferring all the accessories correctly and getting all the hoses and wiring reconnected without leaks or electrical problems. If you have never done this before, consider having a mechanic do at least the removal and installation.
What is the difference between a long block and a crate engine?
A crate engine is a complete, ready-to-run engine that includes all accessories. A long block requires you to add the accessories. Crate engines are more expensive but require less labor to install. The term "crate engine" originally referred to engines shipped in wooden crates, but now it just means a complete, new engine from the manufacturer.
Do I need to replace my old engine's accessories when I install a long block?
Not necessarily. If your alternator, water pump, and other accessories are in good condition and have reasonable mileage, you can reuse them. However, if they are old or worn, it is often smarter to replace them while the engine is out, since you will have straightforward access and will not have to do the job again in a few years.
How long does a remanufactured long block last?
A quality remanufactured long block should last as long as a new one if it was rebuilt correctly. The key is buying from a reputable supplier and following the break-in procedures they recommend. Most come with warranties of 12 months to 3 years, which gives you some protection if something goes wrong early.
What should I ask the seller before buying a long block?
Ask whether the price includes shipping, what warranty is included, whether there is a core charge, what accessories are or are not included, and whether the long block has been tested or run. Also ask for the exact mileage or condition of the engine, and confirm it matches your vehicle's year, make, model, and engine size exactly.