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Cat 3408 Engine

CAT 3408 Engines For Sale

The 3408 Cat engine is a V-8 version of the renowned 3406 I-6. The Caterpillar 3408 engine was first introduced in the 1970’s and continued production up until 1985. At the very beginning of its release, the 3408 Cat engine was considered fairly expensive. However, once it earned reputation for durability, the 3408 subsequently became very popular, especially in marine applications.  The 3408 has a life expectancy of approximately 16,000 hours, which is just shy of 2 years of 'round the clock operation. The 3408 Cat is undoubtedly an extremely versatile engine and is often used in marine vessels, power generation, construction, emergency power, mining, and oil and gas applications. Its V-8 design makes its packaging ideal for medium-sized vessels such as shrimp boats, tugboats, and ferries. Luckily, to this day OEM parts remain available for 3408 marine engines.

Engine Applications and Uses

  • Marine Vessels
  • Power Generation
  • Construction Equipment
  • Emergency Power
  • Mining Equipment
  • Oil & Gas

Common CAT 3408 Problems & Failures

Sadly, engines fail, and while some are savable, others are simply too far gone or aren't worth the time and money to fix. Below, we've included the most common engine failures and issues we encounter with our customers' 3408 engines.

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  • Dropped Valves
  • Camshaft Failure
  • Spun Crankshaft Bearings
  • Cracked Cylinder Heads
  • Scored Pistons and Liners
  • Overfueling
  • Crankshaft Failure
  • Extreme Blow By
  • Lack of Oil Pressure (or no oil pressure)
  • Lifter/Roller Failure
  • Connecting Rod Failure

Caterpillar 3408 Engine Replacement Options

There are an array of issues that can immobilize your engine. Some failures result in the only option being full engine replacement. However, sometimes a few fresh parts can bring it back to life. Or maybe the engine is in need of a long-overdue refresh. Of course, cost, time, and availability will all play a role in your final decision, which is why we offer remanufactured 3408 long blocks.

Cat 3408 Engine Replacement Options Chart

The Big Bear Remanufacturing Process

If a customer’s C15 is unfortunate enough to suffer a serious internal engine failure but at the same time is fortunate in that many of the engine’s external components can be salvaged, our remanufactured Cat 3408 long block is a great solution. An added selling point is that a long block is about as financially feasible as replacing an engine gets.

During a remanufactured long block build, our team of dedicated machinists and engine builders performs a full core tear down, cleaning, inspection, and also handles all machining of the engine before it leaves our facility. This process ensures every Big Bear engine is in perfect running condition each and every time.

It’s important to note that all of our 3408 Caterpillar remanufactured long blocks are built with a mixture of both reman and new parts. We do not recondition or refurbish old engine parts. Instead, we completely rebuild your 3408 back to OEM specs.

Thorough Cleaning

For optimum longevity of your 3408 Cat, we remove all unwanted impurities by stripping the block, heads, rods and camshaft, all of which are then meticulously cleaned in a chemical jet wash or hot tank.


After they've been precision machined to exact tolerances, polished, and magnafluxed, our quality control department performs an extensive inspection on each crankshaft.

Cylinder Heads

To ensure a proper sealing surface exists with the block and to achieve a finish that is compatible with modern head gasket materials, the cylinder heads are resurfaced after passing initial inspection. Valve height is also mic’d and each head is vacuum-tested to ensure correct valve sealing.


The block is magnafluxed to check for any cracks or damage present. To avoid cylinder head distortion after the heads are bolted on and torqued to the block, the cylinders are machined to precise tolerances. In turn, this significantly reduces a prominent cause of engine blow-by. All block surfaces are machined and then thoroughly inspected to achieve a proper finish.


Each 3408 camshaft is inspected and precisely machined to guarantee correct lift for proper valvetrain operation. The cam's lobes are also measured with a micrometer to make certain that all OEM tolerances are met.

Connecting Rods

Every connecting rod is carefully inspected for any signs of bend and/or twist. From there, all rods are cleaned, and then machined to O.E.M specification. That process is followed with each rod being honed to its usual diameter of original equipment, which provides for even distortion of stress on the rod bearings. New bushings are installed and machined in all bushed connecting rods.

New Parts

All-new pistons and rings, bearings, liners, gaskets, and seals come standard on our remanufactured Cat 3408 long blocks. These new parts ensure dependable performance and reliability throughout the life of your engine. The new parts employed in a Big Bear long block are a combination of OEM and aftermarket components.

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Please fill out the form below with your information and request. A member of our staff will be with you shortly.

Remanufactured Engines Standards

In addition, wearable parts are replaced in every single engine. All 3408 Cat engine’s core materials are inspected and examined against the original specifications to ensure correct dimensional tolerances are met. After all, the goal in remanufacturing an engine is to restore it to a state that is as close to new as possible. Replacement parts are either new or requalified (after inspection), and if new, the parts are produced using the exact same manufacturing processes employed on the original Caterpillar 3408 engine. Testing is then performed according to manufacturer specifications and original production standards.

CAT 3408 Long Block Parts List:

  • Timed Front Gear Group
  • Block
  • Cylinder Head (Complete and Loaded)
  • Connecting Rods
  • Crankshaft
  • Intermediate Cover
  • Pistons
  • Liners
  • Rings
  • **1 Year Warranty

*Note: We can provide a new oil pump, oil cooler, water pump, turbo, injectors and fuel pump for additional cost, but these components will not come assembled to the engine.

**First 6 Months Parts & Labor, Second 6 Months Parts Replacement Only. Ask your sales representative for a full copy of our remanufactured long block warranty.

CAT 3408 Spec

Engine Data

Maximum Power400 hp (298 bkW)
EmissionsNSPS Site Compliant Capable or Non-regulated
Displacement14.6L (893 ci)
Compression Ratio14.1:1 to 14.5:1
AspirationNaturally Aspirated or Turbocharged and Aftercooled
RotationCounter-Clockwise (from flywheel end)
Flywheel and Flywheel HousingSAE
Flywheel Teeth136
Weight Net (dry)3,700 lbs (1678.0 kg)
Oil Change Interval750 hours
Ignition, ProtectionAltronic III
Stroke6.500 inches (152.0 mm)
Bore5.400 inches (137.0 mm)
Cooling System54.9 L
Lube Oil System46.2 L

Give us a call today at 844-340-4114 for immediate sales and support for the Cummins 4BT, Cummins 6BT, 6CT, ISC, 855, QSB 4.5 L or CAT 3306. If you have any questions, check out our FAQ Page. We are always ready to help or just listen to your crazy off-roading adventures!

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