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Remanufactured Cummins 4BT (3.9), 6BT (5.9) & CAT 3306 Engines

Big Bear Engine Company Warranty SealWe have the unique ability and talent to remanufacture diesel engines in-house at sister facility in Denver, CO. For customers looking for a more cost-effective option, we offer remanufactured Cummins 4BT (3.9), 6BT (5.9), and CAT 3306 engines. There are two options when it comes to our remanufactured engine program: Exchange and Repair & Return.

Advantages of Remanufactured Diesel Engines by Big Bear Engine Company

AERA Association Member
• Save on Average 57% Over the Dealer
• 88 Point Quality Control Procedure
• Built with All New Parts
• Built to OEM Spec
• ISO 9001 Parts – Less than 1% Failure Rate
• Industry Leading 1 Year Unlimited Miles Warranty
• Same Parts, Engine and Software as a Dealer Engine
• AERA Certified Engine Manufacture
• Built in House in Denver, CO USA
• Extremely Fair Core Acceptance
• 56 Machinists and Master Engine Builders


Exchange engines are remanufactured from all brand new ISO 9001 new parts from an engine core. All parts are machined to exact OEM tolerances and in essence the engine is returned to its original quality unnoticeable from the day it left the factory. Many times older engines are made better than new through remanufacturing as the market has made improvements in parts and technology.

Diesel Camshaft Grinding

Diesel Camshaft Remanufacturing

Upon completion of the new remanufactured Cummins 4BT (3.9), 6BT (5.9) & CAT 3306 engines you simply send us back your old core so we can keep an active inventory of cores for our next customer. Our core policy is very liberal; if the hard internal parts of the engine are salvageable (cylinder head, crankshaft, camshafts and lifters, rocker assemblies and block) then we will return your core deposit in full. If some components are beyond repair we will offer partial credit based upon the value of your core. Engines can also be purchased on an outright basis where the core charge is included into the sale.

The 30 machinists and master engine builders of Big Bear Engine Company have the ability to remanufacture the Cummins 4BT, Cummins 6BT and Caterpillar 3306 back to long block status. Our long blocks come with complete cylinder head, camshaft and lifters, connecting rods, crankshaft, pistons, rings, liners, gaskets, front and intermediate covers. The engine also comes timed and ready to go. The fuel system (injectors, and fuel pumps), water and oil pumps as well as turbochargers can be ordered with the engine but will not be installed on the long block. If you are looking for a drop in crate engine we also have a great article which tells you how to research a crate engine as well as how to properly swap a crate engine into any vehicle or industrial application.

Repair and Return:

Remanufactured Cummins 4BT Engine

Remanufactured Cummins 4BT Engine

Many customers don’t need a fully remanufactured engine but rather have a component or two that need repairing. We have the ability to fully remanufacture individual components back to OEM specifications and return them back to you. We can either do a complete repair and return on your engine, remanufacturer specific components such as the crankshaft or cylinder head or ship you the parts you need to repair non-critical components yourself.

In some instances when components cannot be remanufactured it will become the responsibility of the customer to replace them if they elect to do so. There is no core charge associated with Repair & Return engines and are purchased outright.

Remanufactured Engine Models Offered:

We here at Big Bear Engine Company specialize in medium duty diesel engines (4BT, 6BT, 3306) however if we have the capability to remanufacture just about any engine. Aside from our remanufactured Cummins 4BT (3.9), 6BT (5.9) & CAT 3306 engines, these are the engines we can remanufacture:

Caterpillar: CAT 3116, CAT 3126, CAT 3208, CAT 3304, CAT 3306, CAT C7, CAT C12, CAT C13, CAT C15, CAT 3406, CAT 3408, CAT 3412

Cummins: Big Cam 855, N14, ISX, ISL, ISM, ISC, M11

Detroit Diesel: 60 Series, 14.0 L, DDEC III, DDEC IV, DDEC V

International: DT466, DT530

Mack: E6, E7, E7-Etech, E7-Aset, MP7

John Deere: 4045, 6068, 6101

*Note: We do not do gas engines or light duty diesel truck engines

Give us a call today at 844-340-4114 for immediate sales and support for the remanufactured Cummins 4BT, Cummins 6BT 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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