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How to Properly Research and Buy a Cummins 4BT Crate Engine

When seeking out an industrial 4BT diesel engine it can be overwhelming with the vast amount of information available about what is the best engine selection for your budget and timeframe. The good news is there are options for every customer including Component Build 4BTs, Remanufactured 4BT Engines and Used 4BT Engines. This article will hopefully alleviate some of the burden and guide you in the right direction.

Cummins 3.9L 4BT Extended Long Block Crate Engines:

The term “crate engine” gets thrown around a lot in the automotive and diesel industry. Some companies will consider a crate engine as all brand new internal components but used ancillary parts such as the water pump, oil pump, injectors, turbo etc… However, the accepted definition of a crate engine is an extended long block (75% finished build) engine assembled with aftermarket parts. Crate engines get their name from the wooden crates they would usually come in.

Cummins 4BT Crate Engine

Cummins 4BT Crate Engine with Example Side View of Crate

Our 4BT Extended Long Block Crate Engines are a bit of a hybrid between a true crate engine and a surplus engine from Cummins. Our 4BT internal castings are made in an OEM facility and are built back to popular CPLs (critical parts list). Our crates engines are called 'component builds' usually consisting of roughly 90% OEM parts, 10% aftermarket when available. The patents for these engine assemblies expired many years ago; that being said the same manufacturers now supply both OEM and Aftermarket parts from the same facility. They are the exact same parts but just go in a different box stamped OEM or Aftermarket.

Cummins 4BT Crate Engines (Extended Long Block) come in different configurations to fit various applications and needs of our customers. For example, the 4BT comes in 105 HP, 130 HP and 140 HP and can be shipped as an extended long block or a long-block. Extended long blocks are about a 75% finished assembly. Some customers find a long block to more economical if they currently have a 4BT that is no longer working. For example a skid steer with a 4BT that has a rod through the block, dropped valve or spun crankshaft bearing will ruin the hard internal components of the engine. Everything else on the engine can be reused from the old engine. We can simply build them a new long block and replace the central rotating structure and save the customer a significant amount of money over a new complete engine.

Note that not all Cummins 4BT Crate engines are created equal. Many advertise dirt cheap prices only for you to find out that the 4BT you’ve been quoted is just the short-block (no cylinder head) with many items to upsell.

Surplus 4BT Engines:

Cummins 4BT Engine

Cummins 4BT Surplus / Crate Engine

Surplus Engines/Parts are brand new assemblies direct from the manufacturer usually from the dealer. The term “surplus” means left over or extra. It could be that the manufacturer made a run of 50,000 internal castings but only sold 40,000 before production stopped. Diesel engines are phased out all the time due to model changes or variations in the serial numbers. The left over engines are essentially brand new but are left over from the production run or sold to a wholesaler. This list from Cummins and Leega Power JV shows the locations of all Cummins Engine Manufacturing Facilities across the world. Cummins either owns the facility outright, has joint ventures or simply licenses out their techniques and parts much like a franchise. Cummins 4BT engines as well as 5.9 L (6BT) are manufactured all over the world including: Izmir, Turkey, São Paulo, Brazil, Rocky Mount, North Carolina, Charleston, South Carolina, Darlington, England, Xiangfan, China, Oyama, Japan and Jamshedpur, India. Surplus and Crate Engine parts are sometimes used interchangeably within the industry for this very reason.

Remanufactured 4BT Engines:

Ah yes, “remanufacturing”. What exactly does that mean specifically? The term remanufacturing according to the Automotive Parts Remanufacturers Association (APRA) is as follows:

“Remanufacturing is a standardized industrial process* by which cores are returned to same-as-new, or better, condition and performance. The process is in line with specific technical specifications, including engineering, quality and testing standards. The process yields fully warranted products. An industrial process is an established process, which is fully documented, and capable to fulfill the requirements established by the remanufacturer.”

Remanufactured Cummins 4BT Engine

Remanufactured Cummins 4BT Engine

Remanufacturing vs. Reconditioning is something to be aware of in the industry. A remanufactured 4BT engine is re-built from the ground up using various grinding, welding, surfacing and line boring machinery to bring back a used engine core back to OEM spec. The remanufactured engine is like brand new again. This means the camshaft, crankshaft, cylinder heads, pistons, connecting rods, block and timed gear train are all machined. A reconditioned engine is a used engine that has simply been refurbished. This might mean the engine is power washed, the bearings and gaskets swapped out, and new turbo and injectors are installed. The hard internal components are not machined.

We here at Big Bear Engine Company, primarily focus on Cummins 4BT Extended Long Block Engines and Used 4BTs. Our remanufacturing facility and full machine shop in Denver, CO is set up to do about 8.0 L and above heavy duty diesel engines. That being said from time to time we will build a fully remanufactured 4BT long block. The advantages of remanufactured engines over crate or surplus 4BT engines is the cost savings. However the drawbacks to a remanufactured 4BT engine are time. Depending on the machine shop’s production schedule you could wait 2-3 weeks to receive you engine. This downtown could be disastrous if the 4BT is in a critical piece of industrial equipment.

Used 4BT Engines:

There is definitely more "grey area" when negotiating for a used diesel engine deal. You should know going in that you will be receiving a used diesel engine that was operated by another customer right out the gate. Unlike a Cummins 4BT Crate Engine or Surplus Engine, buying anything used can be a bit of a challenge but we can give you some tips on how to protect yourself when purchasing a used 4BT diesel engine.

Pro Tip 1: Do Not Buy Something Off of eBay –

Follow the old adage, “If it is too good to be true it probably is.” There are some smokin’ hot deals on eBay however you run the risk of getting a lemon. eBay protects its customers via an escrow program however, it can be a nightmare dealing customer service. Many have had problems trying to ship an engine back or receive a refund in a timely manner from eBay. Usually there are no warranties on a used Cummins 4BT eBay engine either. If the transaction goes well but 30 days later the engine explodes you are still out of luck.

Pro Tip 2: Do Buy an Engine from a Reputable 3.9L 4BT Cummins Dealer –

Remanufactured 4BTs and Cummins 4BT Crate Engines (Extended Long Blocks) are our bread and butter however we also supply used 4bt engines from our network of trusted partners. Our network contains 28 partner salvage and heavy duty diesel engine core suppliers from all over the world. These are not just companies put rather friends we know and trust. There is Ronnie from Texas, Bill from Missouri or Rodney from Denver. These folks know the used engine market and have eyes and ears on the ground. We trust them to provide us with good rebuildable cores for our own reman engine builds and we also trust them to supply us the perfect 4BT used engine. If something goes wrong we know any of those 28 contacts will have our back; can you say the same about a Craigslist or eBay ad?

A reputable diesel engine company will be able to provide some references, are part of a trade association like the AERA and have no glaring issues or problems with Yelp, Pissed Consumer, Ripoff Report or the Better Business Bureau. Do your homework!
Cummins 4BT Used Engine Checklist

Pro Tip 3: Ask the Right Questions –

The bottom line is that you want a good used 4BT runner not something that will fall apart the minute you drop it in. Your goal as a consumer is to do your due diligence and learn as much as you can about the engine you are getting.

• Ask for pictures of the engine
• Look for rust or a power-wash of the engine
• Look to see if the company painted the engine
• Ask for miles ran, maintenance and log records
• Ask for oil pressure and blow-by report
• If the company offers a full dyno report
• Ask if the company can drop the oil pan and inspect the crankshaft
• Ask if the company can remove the valve cover and inspect the head, camshaft and injectors
• Ask the company to inspect the gaskets, oil pump, water pump and aftercooler
• Ask if the company can inspect the turbo
• Ask for the engine serial number, CPL and any accident history of the engine/truck
• Ask about the warranty policy and how the company handles warranties

Final Takeaways

Whether you are in the market for a 3.9L / 4BT Cummins Crate engine for your Jeep Swap or Industrial Application we’ve got your back. We know a Cummins 4BT, 5.9L or CAT 3306 is a large investment and you just want to get back on the road. We hear you! It is our hope that this information can assist you during your purchasing journey. We would love it if you bought from us, but if you don’t, please protect yourself from making a decision you might regret.

Give us a call today at 844-340-4114 for immediate sales and support for the 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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