Jeep Wrangler driving off-road with a 4BT Cummins engine
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Cummins 4B, 4BT Long Block Engine Options

Cummins 4B (3.9 L) Causes of Failure and Long Block Replacements

A new Cummins 4BT long block is an economical solution for a majority of customers who have a catastrophic internal engine failure. Major internal engine failure can include:

  • Spun Crankshaft Bearing
  • Cracked Cylinder Head(s)
  • Scored Pistons and Liners
  • Dropped Valves
  • Camshaft Failure
  • Crankshaft Failure
  • Hole through the Engine Block
  • Lifter/Roller Failure
  • Connecting Rod Failure
  • Over Fueling
  • Lack of oil or oil pressure
  • Extreme Blow By

4BT Connecting Rod Hole in Block

4B Long Blocks Multiple

4B Long Blocks Ready for Final Crating

A Cummins 4BT long block is considered a 50-75% engine and does not include the fuel system, turbo, inlet or exhaust manifolds, water pump etc... Essentially, if a catastrophic internal hard part failure occurred within the 4BT Cummins block the engine experienced hard internal failure but the ancillary components are in good working order, a long block is one of the most cost effective solutions vs. a extended long block. Many customers think that a long block with the labor to assemble the engine back to complete status will be more expensive but that is simply not the case. On average, it takes roughly 5-10 hours to assemble a 4BT long block. With a shop labor rate of $130 per hour you're looking at $650 or so. The cost savings over an extended long block or full reman unit is a few thousand dollars on average.

Fuel Pump Configurations

4B Long Block (Inline A Pump) 1

4B Long Block - Bosch A Inline Setup

Our Cummins 4BT long blocks come in three different styles based upon the most popular fuel pump options: Bosch A Inline Pump, Bosch P-7100 or P-3000 Inline Pump or the Delphi/Lucas Cav/Bosch VE, VP15 Rotary Fuel Pump. Each 4B long block is configured with different gear housings and front covers to accommodate the appropriate fuel pump. The 4B Engines are found at various HP ratings from 60-140 and uses the same pistons and setup for 7 mm injectors; injectors are not included.

Long Block Parts List

Our 4B long blocks options come with:

  • Engine Block
  • Cylinder Head (7mm injector setup)
  • Camshaft
  • Followers/Lifters
  • Pistons
  • Liners
  • Rings
  • Connecting Rods
  • Oil Pump
  • Oil Cooler (later models)
  • Rocker Assemblies
  • Intermediate Cover
  • Timed Front Gear Group
  • Crankshaft
  • Rear Sump Oil Pan

Fits Equipment/Vehicle Types

4B Long Block (Rotary VE Pump) 2

4B Long Block - VE/VP Rotary Pump Setup

The 4B long block engine is popular in both automotive and industrial applications. You'll find Cummins 4BT engines in Case Skid Steers, Doosan, JLG, Skytrak, Skyjacks, Genie Forklifts, Scissor Lifts, Telehandlers, Boom Lifts, Generator Sets, Komatsu Trenchers, Compact Rollers, Pavers, Swathers, Excavators and Conveyor Belts. Cummins 4B / 4BT units are also popular in Step-Vans and small automotive units like Airport Baggage Carts, RVs, Water Trucks and Small Flat-Bed Trailers.


All replacement 4BT Cummins blocks are built with a combination of new aftermarket and OEM components and castings.  All new 4B engines come with a 12 months unlimited hours/miles parts warranty. Warranty covers and component or factory defect only. We also have optional 1 and 2 year parts/labor extended warranties available.

Quality Control Measures

All of our new extended long blocks are run tested before they leave the factory floor; this is to ensure quality and workmanship. Our Cummins 4B long block assemblies are put through rigorous quality control measures to make sure they meet OEM spec but are not dyno/run tested since a long block is only half assembled.

Give us a call today at 844-340-4114 for immediate sales and support for the Cummins 4BT long block, 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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4BT Long Block Engine Gallery

4B Long Block 1
4B Long Block 2
4B Long Block 3
4B Long Block 4
4B Long Block (Inline A Pump) 2
4B Long Block (Inline A Pump) 3
4B Long Block (Inline A Pump) 4
4B Long Block Inline Setup
4B Long Block (Rotary VE Pump) 1
4B Long Block (Rotary VE Pump) 2
4B Long Block (Rotary VE Pump) 3
4B Long Block (Rotary VE Pump) 4

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