3945670
Main Bearing Cap
Cummins®

Introduction

The Cummins 3945670 Main Bearing Cap is a critical component designed for use in heavy-duty truck engines. Its primary function is to support the crankshaft, contributing to the engine’s stability and efficiency. This part is essential for ensuring smooth and reliable engine performance under demanding conditions.

Function and Operation

The Cummins 3945670 Main Bearing Cap supports the crankshaft by securing the main bearings in place. This support is vital for maintaining the crankshaft’s alignment and stability during engine operation. The main bearing cap, in conjunction with the main bearings, helps to reduce friction between the crankshaft and the engine block. This reduction in friction minimizes wear and tear on the crankshaft, enhancing the engine’s longevity and performance ¹.

Key Features

The Cummins 3945670 Main Bearing Cap is engineered with specific design characteristics to ensure optimal performance. It is typically made from high-strength materials that provide durability and resistance to wear. The structural integrity of the cap is designed to withstand the high loads and stresses encountered in heavy-duty applications. Additionally, the cap may feature precision machining and tight tolerances to ensure a proper fit and alignment with the crankshaft and main bearings ².

Benefits

The use of the Cummins 3945670 Main Bearing Cap offers several advantages. It contributes to improved engine reliability by providing stable support for the crankshaft. This stability helps to reduce the likelihood of engine failures due to misalignment or excessive wear. Additionally, the cap’s design may lead to reduced maintenance requirements, as its durable construction and precise fit help to minimize the need for frequent replacements or adjustments. Overall, the cap enhances the engine’s performance by ensuring smooth operation and efficient power transmission ³.

Installation and Maintenance

Proper installation of the Cummins 3945670 Main Bearing Cap is crucial for ensuring its effectiveness and the engine’s performance. Installation guidelines typically include torque specifications to ensure the cap is securely fastened without over-tightening, which could lead to damage. Alignment procedures are also important to maintain the crankshaft’s proper position within the engine block. Routine maintenance practices, such as regular inspections for wear and proper lubrication, are recommended to ensure the longevity and optimal performance of the main bearing cap.

Troubleshooting Common Issues

Common issues associated with main bearing caps include bearing wear, oil leaks, and misalignment. Bearing wear can occur due to insufficient lubrication or excessive loads, leading to increased friction and potential engine damage. Oil leaks may indicate a compromised seal or gasket, requiring inspection and repair. Misalignment can result from improper installation or wear on the cap or crankshaft, affecting engine performance. Troubleshooting these issues involves a systematic approach to diagnose the problem, such as checking lubrication levels, inspecting for physical damage, and ensuring proper alignment and fit.

Cummins Overview

Cummins Inc. is a well-established manufacturer in the automotive industry, known for its commitment to quality and innovation in engine components. With a history of producing reliable and high-performance engines and parts, Cummins has built a reputation for excellence. The company’s product offerings span a wide range of engine types and components, designed to meet the demanding requirements of various applications. Cummins’ dedication to quality is evident in its rigorous manufacturing processes and continuous investment in research and development.

Compatibility of Cummins Main Bearing Cap Part 3945670

The Cummins Main Bearing Cap part number 3945670 is designed to fit a variety of Cummins engines, ensuring reliable performance and durability. Here is a detailed overview of its compatibility across different engine models:

Cummins B and 6BT Series Engines

• 6B5.9
• B6.7 G
• B125

The part 3945670 is compatible with the B and 6BT series engines, which are known for their robust construction and efficiency. These engines are often used in heavy-duty applications, and the main bearing cap plays a crucial role in maintaining the integrity of the engine’s crankshaft.

Cummins ISB Series Engines

• ISB (Chrysler)
• ISB CM2150
• ISB CM550
• ISB CM850
• ISBE CM2150
• ISBE CM800

The ISB series engines, including the ISBE variants, benefit from the part 3945670. These engines are widely used in various industries due to their power and reliability. The main bearing cap is essential for supporting the crankshaft and ensuring smooth operation.

Cummins QSB Series Engines

• QSB5.9 44 CM550
• QSB5.9 CM850
• QSB6.7 CM850 (CM2850)
• QSB7 CM2880 B117

The QSB series engines, including the QSB6.7 and QSB7 models, are designed for demanding applications. The part 3945670 is compatible with these engines, providing the necessary support for the main bearings. This ensures that the crankshaft remains stable and reduces wear over time.

Cummins ISB/ISD Series Engines

• ISB/ISD6.7 CM2150 SN

The ISB/ISD series engines are known for their versatility and performance. The main bearing cap part 3945670 is specifically designed to fit these engines, ensuring optimal performance and longevity.

By ensuring that the main bearing cap part 3945670 is correctly installed, engine owners can maintain the reliability and efficiency of their Cummins engines. This part is a critical component in the engine’s overall performance, and its compatibility across various models underscores its importance in the engine’s operation.

Role of Part 3945670 Main Bearing Cap in Engine Systems

The Main Bearing Cap, identified by part number 3945670, is integral to the structural and functional integrity of several key engine components.

Integration with the Block

The block, or engine block, serves as the primary structure of the engine, housing the cylinders and providing a foundation for other components. The Main Bearing Cap is bolted to the block, securing the main bearings in place. This arrangement ensures that the crankshaft is properly supported and aligned within the engine, facilitating smooth and efficient operation.

Interaction with the Cylinder

While the cylinder itself is primarily responsible for containing the combustion process, the Main Bearing Cap indirectly supports its function. By maintaining the stability and alignment of the crankshaft, the cap ensures that the pistons move within the cylinders with precision. This precision is essential for optimal combustion efficiency and overall engine performance.

Relationship with the Cylinder Block

The cylinder block is a comprehensive assembly that includes the cylinders, coolant passages, and other integral features. The Main Bearing Cap is a critical component in this assembly, as it helps to maintain the structural integrity of the cylinder block. By securing the main bearings, it ensures that the crankshaft remains stable, which is vital for the consistent operation of the cylinder block.

Contribution to the Cylinder Block Kit

In a cylinder block kit, which typically includes the cylinder block along with various gaskets, seals, and other necessary components, the Main Bearing Cap plays a supportive role. It ensures that all components within the kit function harmoniously. The cap’s role in securing the main bearings is essential for the proper installation and operation of the cylinder block kit, contributing to the overall reliability and performance of the engine.

Conclusion

The Cummins 3945670 Main Bearing Cap is a vital component in heavy-duty truck engines, ensuring the stability and efficiency of the crankshaft. Its design and features contribute to the engine’s reliability and performance, making it an essential part for maintaining the integrity of Cummins engines across various models.