Jeep Wrangler driving off-road with a 4BT Cummins engine
Call us

Cat 3066 Engine

CAT 3066 Engines For Sale

CAT 3066 EngineThe Caterpillar 3066 Engine is a reliable engine capable of producing up to 143 hp. Its design was intended to aid the comfort of the operator by reducing the amount of sound and vibration produced by the engine. The Cat 3066 is an inline-six, turbocharged diesel built for power, reliability, fuel economy, and low emissions that can keep the application it’s powering running at its peak, efficient performance.

Engine Applications and Uses

  • Construction
  • Industrial
  • Agricultural
  • Heavy Equipment

Common CAT 3066 Engine Problems & Failures

Customers looking to replace their 3066 Cat usually have a motivation for doing so. In working with these engines for a number of years, we’ve earmarked the common themes and pattern problems that are often reported as primary reasons someone would seek to replace their 3066. Below, we’ve assembled a list of these issues—some of which unfortunately mean the engine is at the end of the road. However, some of the frequent problems that follow are fixable.

AERA Association Member

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

Caterpillar 3066 Engine Replacement Options

There are a host of issues that can harm your engine, but not all of them mean the engine is dead in the water. While certain failures do mean the engine is beyond saving, at times some power plants simply need a few replacement parts, or a refresh. We at Big Bear Engine Company understand that factors such as time, money, and availability factor into your decision when it comes to buying a new engine—and that’s exactly why we provide remanufactured long block options.

The Big Bear Remanufacturing Process

A remanufactured 3066 Cat long block is a wise choice for someone who has had the misfortune of suffering a severe breakdown, especially if there are reusable external parts from the old engine that can be swapped over. Perhaps more importantly, our reman long blocks are a great option if you’re trying to work on a budget.

Our team of dedicated machinists and engine builders will execute a full core tear down, cleaning, inspection, and machining of your Caterpillar 3066 before it leaves our facility. The ability to remanufacture the engine completely in-house ensures perfection each and every time. We follow the same, extensive quality control process with every engine we build.

Our method of remanufacturing 3066’s means they’re constructed with both reman and new parts. Please note, we do not recondition or refurbish old engine parts. Instead, we completely rebuild your old Caterpillar 3066 engine back to OEM specs.

Thorough Cleaning

A thorough cleaning is essential in the engine rebuilding process. Our goal is to spot any impurities or potential structural flaws that could contribute or cause both component failure or engine failure. Our cleaning process begins by stripping the 3066 and then sending the block, head, rods, crankshaft, and camshaft through a chemical jet wash or hot tank.


Each Cat 3066 crankshaft is precision machined to exact tolerances, polished, and then magnafluxed. The crankshaft also undergoes a thorough inspection, performed by our quality control department, to ensure quality is maintained.

Cylinder Heads

It is imperative that the final product is compatible with all modern gasket materials. Therefore, all 3066’s heads are resurfaced to ensure a proper sealing surface with the block and head gasket. Valve height is mic’d, and each head is vacuum-tested to assure correct valve seating.


The 3066 block is carefully inspected, using magnetic particle, for any cracks and imperfections. The cylinders are then bored, honed, and inspected once again. Torque plate honing is also performed on some engines in order to eliminate the chance of cylinder distortion after the head is installed and torqued to the block. This process ensures that a major cause of engine blow-by is eliminated. Block surfaces are then machined and inspected to ensure proper finish.


The camshaft is examined and precisely machined to provide correct lift. Lobes are measured with a micrometer to ensure OEM tolerances are met.

Connecting Rods

Every Cat 3066 connecting rod is carefully inspected for signs of bend and/or twist. All rods are thoroughly cleaned, machined to O.E.M. specifications, and then honed to the standard diameter of original equipment to ensure even distribution of stress across the bearings. New bushings are also fitted and machined in all bushed connecting rods.

New Parts

All Caterpillar 3066 long blocks receive a number of new parts as standard equipment. These parts include pistons and rings, bearings, gaskets and seals, and liners. New parts assure dependable performance and reliability throughout the life of your engine, and these new parts are a blend of both OEM and aftermarket components, when available.

Request a Quote

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

Remanufactured Engines Standards

For the best possible result, our remanufacturing process aims to make the engine as close to new as possible. All wearable parts are routinely replaced, and all 3066 core material is carefully inspected and examined against the original equipment specifications for the correct dimensional tolerances. Replacement parts are either new or requalified. We also mirror the same production processes as the original equipment if or when new parts are required. Testing is then performed to manufacturer specifications and original production standards.

CAT 3066 Long Block Parts List:

  • Timed Front Gear Group
  • Block
  • Crankshaft
  • Connecting Rods
  • Complete Loaded Cylinder Head
  • New Upper and Lower Gasket Set
  • Intermediate Cover
  • Camshaft
  • Followers/Lifters
  • 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 with the long block, but these parts 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 3066 Specs

Engine Data

Displacement6.4L (389 ci)
Bore4.02-inch (102 mm)
Stroke5.12-inch (130 mm)
Gross Power107 kW (143 hp)
EmissionsUS Tier 2 and EU Stage II

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!

Request A Quote


Got an Engine Down?

Discover your best options!
Get our FREE 8-Page Diesel Engine Replacement Guide

    I am looking for an