Parts For 3.9 4BT Cummins Engines

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The 3.9L 4BT diesel is a popular choice for many swaps or conversions. XDP offers a large selection of stock replacement and aftermarket parts from all the leading manufacturers. Whether you are looking to upgrade your vehicle or simply doing routine maintenance, XDP is your one-stop-diesel-shop.

The 3.9L 4BT was an inline 4-cylinder turbocharged diesel engine that was introduced in 1984. This small-scale diesel engine was designed with simplicity and durability in mind. The 4BT was initially created for agricultural, industrial, and light-duty commercial use. This engine received the nickname the bread truck because it was frequently used in delivery trucks. Many components from the 12 valve 6BT were shared with this engine including the solid foundation of a cast-iron block, internal engine components, and a direct injection fuel system. The lack of electronic controls in this engine also provided increased reliability and simplicity.

Similar to the 12 Valve 6BT, the 4BT had an overhead valve design with 2 valves per cylinder and a forged-steel crankshaft. The 3.9L was constructed with a cast-iron block and cylinder head capable of enduring the harshest conditions. This engine contained cast-aluminum pistons and forged-steel connecting rods to handle increased cylinder pressure. For more efficient combustion the 4BT utilized a direct injection fuel system with a gear-driven injection pump. The highly reliable Bosch P7100 injection pump was paired with mechanical injectors that sprayed fuel directly into the combustion chamber. Fitted to the 3.9L was a fixed-geometry turbocharger that was completely mechanical, which reduces failure points. The simplicity and reliability of this engine makes it a popular choice for diesel engine swap projects on Jeeps, SUVs, and small pickups. The 4BT can be paired with a variety of different transmissions which makes diesel swapping different vehicles even easier. In addition, this engine was relatively small compared to other diesel engines at the time, with dimensions of 30.6” in length, 24.6-inch wide, and 37.7-inch tall.

Diesel engines are typically known to be fuel efficient and this 4-cylinder turbo diesel was no exception, by delivering almost 21 mpg in certain applications. A stock 3.9L 4BT was rated at 105 hp and 265 lb-ft of torque, but much like the 12-valve 5.9L its built to handle increased power. In 1994 the 3.9L 4BT engine was discontinued, but many of these engines are still readily available. XDP carries parts and accessories from hundreds of the top manufacturers to ensure you have the parts necessary to keep your 3.9L running the way it should. Find all the diesel performance parts your 4BT Diesel engine needs at XDP.