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

When you’re on the hunt for a Cummins 4BT, the process can be overwhelming. With so many different variants of this engine being produced, a vast amount of information (and opinions) is available about what the best engine is for your particular budget, project and timeframe. The good news is there are options for every customer, including “component build” 4BTs, remanufactured 4BT engines and even used 4BT engines. This article will alleviate some of the burden(s) associated with hunting down the right Cummins 4BT for your needs.

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 consider a crate engine one that was assembled with 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-percent finished build) engine assembled with aftermarket parts. Crate engines originally got their name from the wooden crates they were shipped in.

Cummins 4BT Crate Engine

Cummins 4BT Crate Engine with Example Side View of Crate

Our 4BT Extended Long Block Crate Engines

are perfect for anyone seeking optimal peace of mind in their diesel repower. They 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 (control parts list), not to mention that our crate engines are referred to as “component builds,” engines that usually consist of roughly 90-percent OEM parts and 10-percent 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 for these engines from the same facility. They are the exact same parts but just go in a different box, one that’s either stamped OEM or aftermarket.

Our Cummins 4BT crate engines (Extended Long Blocks) come in different configurations in order to fit various applications, as well as the specific needs of our customers. For example, the 4BT comes in 105 hp, 130 hp and 140 hp power ratings, and can be shipped as an extended long block or a long block. As mentioned, extended long blocks are about a 75-percent finished assembly. Some customers find a long block to more economical if they currently have a 4BT that is no longer running. For instance, take a skid steer with a 4BT that has thrown a rod through the block, dropped a valve or spun a crankshaft bearing. This can ruin the hard internal components of the engine, but essentially everything else on the engine can be reused. We can simply build these customers a new long block and replace the central rotating structure, which saves the customer a significant amount of money over a completely new engine.

Note that not all Cummins 4BT crate engines are created equal. Many advertise dirt cheap prices only for you to find out later that the 4BT you’ve been quoted is a short-block (no cylinder head). They will then present you a long list of upsell items, which will quickly (and sharply) increase the cost of the engine.

Surplus 4BT Engines:

Cummins 4BT Engine

Cummins 4BT Surplus / Crate Engine

Surplus engines and parts are brand new assemblies that come direct from the manufacturer, and usually from a dealer. The term “surplus” means left-over or extra. A surplus could result from the manufacturer making a run of 50,000 internal castings but only selling 40,000 before production stopped. Diesel engines are phased out all the time due to model changes or variations in serial numbers. The phased-out engines are essentially brand new but are left over from the production run or are 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 to them (much like a franchise). Cummins 4BT engines, as well as the 5.9L (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 diesel industry for this very reason.

Remanufactured Cummins 4BT Engines:

So what, exactly, does the term “remanufacturing” mean? According to the Automotive Parts Remanufacturers Association (APRA), it’s defined in the following manner:

“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 you’ll want to be aware of as well. A remanufactured 4BT engine is re-built from the ground up using various grinding, welding, surfacing and line boring machinery to bring a used engine core back to OEM specs. The remanufactured engine is like brand new again. This means the crankshaft, camshaft, cylinder head(s), connecting rods, block and 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 installed. The hard internal components are not machined and often go completely untouched..

At Big Bear Engine Company, we primarily focus on Cummins 4BT extended long block engines and used 4BTs. Our remanufacturing facility and full machine shop in Denver, Colorado is equipped to handle 8.0L and larger 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 biggest drawback of a remanufactured 4BT engine is time. Depending on the machine shop’s production schedule, you could wait two to three weeks before receiving your 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" associated with sourcing a used diesel engine than a remanufactured version. First things first, you need to know that you will be receiving a used diesel engine that was operated by another user. The manner and conditions through which it was operated will likely be unknown to you. Unlike a Cummins 4BT crate engine or surplus engine, buying anything used can be a bit of a challenge. However, the following tips are intended to help protect you when purchasing a used 4BT diesel engine.


Pro Tip 1: Beware The eBay Engine

The old adage, “If it’s too good to be true, it probably is,” applies here. There are often some smokin’ hot engine deals on eBay. However, with every one of them you run the risk of getting a lemon. eBay does protect its customers via an escrow program, but it can be a nightmare dealing with customer service should your engine not be what was advertised. Many buyers have had problems trying to ship an engine back or receive a refund in a timely manner. And in most cases, 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 Cummins 4BT Dealer

Remanufactured 4BT and Cummins 4BT crate engines (extended long blocks) are our bread and butter here at Big Bear Engine Company. However, we also supply used 4BT engines from our network of trusted partners. This expansive network contains 28 partner salvage and heavy-duty diesel engine core suppliers from all over the world. These are not just companies but rather friends we know and trust. There is Ronnie from Texas, Bill from Missouri and 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 operation 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 Marketplace or eBay seller?

A reputable diesel engine company will be able to provide some references, are likely part of a trade association like the AERA, and have no glaring issues or problems with Yelp, PissedConsumer, Ripoff Report or the Better Business Bureau. They will also likely offer some type of warranty. As for us, every remanufactured Cummins 4BT from Big Bear Engine Company comes with a comprehensive, nationwide warranty. 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 should be to perform your due diligence and learn as much as you can about the engine you are getting. If you don’t, you could easily end up buying two engines before your project is completed or your piece of equipment is operational again.

*Request pictures of the engine, as well as video if at all possible

*Inspect closely for rust, or a power-wash of the engine

*Look to see if the company repainted the engine

*Inquire about miles and/or hours accumulated, along with maintenance and log records

*Ask for an oil pressure and blow-by report

*Find out if the company selling the engine offers a full dyno report

*Ask if the company can drop the oil pan and inspect the crankshaft

*Inquire about removal of the valve covers to inspect the head, camshaft, and injectors

*Ask the company to inspect the gaskets, oil pump, water pump, and (if applicable) aftercooler

*Ask for an inspection on the condition of the turbo

*Request the engine’s serial number, CPL and any accident history on the engine/truck it came in

*Find out all the details on the company’s warranty policy, as well as how the company handles warranty claims

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 will 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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