3900687
Expansion Plug
Cummins®

Introduction

The Expansion Plug 3900687 is a component manufactured by Cummins, a well-established name in the commercial vehicle industry. This part is specifically designed for use in commercial trucks, where it plays a role in maintaining the integrity of various vehicle systems. Expansion plugs, in general, are utilized to seal openings in engine blocks, radiators, and other components, ensuring that these systems operate efficiently under a range of conditions ¹.

Basic Concepts of Expansion Plugs

Expansion plugs are mechanical devices that seal openings in various automotive and industrial applications. They function based on the principle of thermal expansion and contraction. When an expansion plug is heated, it expands to fill the space it occupies more completely, creating a tighter seal. Conversely, as it cools, it contracts slightly, allowing for minor adjustments in the sealed environment without compromising the seal. This characteristic makes them suitable for applications where temperatures fluctuate ².

Purpose of the 3900687 Expansion Plug

The 3900687 Expansion Plug is designed to maintain system integrity in commercial trucks by sealing specific openings in engine components. Its role is particularly important in environments where temperature variations are common, as it helps to prevent leaks and maintain pressure within the system. By doing so, it contributes to the overall efficiency and reliability of the truck’s engine and associated systems ³.

Key Features

The 3900687 Expansion Plug boasts several key features that enhance its performance and durability. It is constructed from high-quality materials that can withstand the thermal and mechanical stresses encountered in commercial truck applications. Its design includes elements that ensure a secure fit and effective sealing, even under varying temperature conditions. Additionally, the plug may feature unique attributes such as anti-rotation mechanisms or special coatings to further improve its functionality and longevity.

Benefits

Utilizing the 3900687 Expansion Plug in commercial truck applications offers several advantages. It contributes to improved system reliability by ensuring that seals remain intact under a range of operating conditions. This can lead to enhanced safety, as the risk of leaks or system failures is reduced. Moreover, the durability and effectiveness of the plug can result in potential cost savings over time, as the need for frequent replacements or repairs is minimized.

Installation Considerations

Proper installation of the 3900687 Expansion Plug is crucial for its optimal performance. Guidelines and best practices should be followed to ensure correct sizing, proper seating, and adherence to torque specifications. These steps are important to achieve a secure and effective seal, preventing issues such as leaks or inadequate pressure maintenance within the system.

Troubleshooting and Maintenance

Common issues with expansion plugs can include leaks or failure to seal properly. Troubleshooting these problems may involve checking for correct installation, assessing the condition of the plug, and ensuring that it is compatible with the application. Maintenance tips for prolonging the life of the 3900687 Expansion Plug include regular inspections for signs of wear or damage and following manufacturer guidelines for replacement intervals.

Cummins: A Brief Overview

Cummins Inc. is a global power leader that designs, manufactures, and distributes engines, filtration, and power generation products. With a rich history and a diverse product range, Cummins is recognized for its commitment to quality and innovation in the commercial vehicle industry. The company’s engine components, including the 3900687 Expansion Plug, are designed with a focus on reliability, performance, and durability, reflecting Cummins’ dedication to excellence in manufacturing.

Compatibility of Cummins Expansion Plug Part 3900687 with Various Engine Models

The Cummins Expansion Plug part number 3900687 is designed to fit a variety of Cummins engine models. Below is a detailed breakdown of the engines with which this part is compatible, grouped by engine series and model variations:

B Series Engines

• B3.9 G
• B4.5
• B5.6 CM2670 B152B
• B5.9
• B5.9 CM2670 B166C
• B5.9 GAS PLUS CM556

G Series Engines

• G5.9
• G5.9 CM558

ISB Series Engines

• ISB CM550
• ISB3.9 CM2220 B107
• ISB5.9 CM2880 B110
• ISB5.9 CM2880 B127
• ISB5.9 CM2880 B140
• ISB5.9 CM2880 B149
• ISB5.9G CM2180

QSB Series Engines

• QSB3.9 30 CM550
• QSB3.9 CM2880 B138
• QSB5.9 30 CM550
• QSB5.9 44 CM550
• QSB5.9 CM2880 B115
• QSB5.9 CM2880 B139
• QSB5.9G

This expansion plug is engineered to ensure a secure fit and optimal performance across these diverse engine models, providing a reliable solution for maintaining the integrity of the engine’s cooling system.

Role of Part 3900687 Expansion Plug in Engine Systems

The expansion plug, identified by part number 3900687, serves a significant function within various engine systems. Its primary role is to seal and secure specific components, ensuring the integrity and efficiency of the engine’s operation.

Integration with Cylinder Blocks

In the context of cylinder blocks, such as the Block 6-B Short, Short 4BT, Short 4BTA, Short 6-BT, Short 6BT, Short E2 Incent, Short E3 Incent, and Short Euro1, the expansion plug is utilized to seal unused or non-functional passages. This prevents coolant or oil leakage, maintaining the engine’s thermal efficiency and lubrication system integrity.

Application in Short Blocks

For short blocks, including the Short 6-B Block, Short 6B Block, and Short E2 215/235 Block, the expansion plug is essential in sealing core plugs or freeze plugs. This ensures that the block remains airtight, which is vital for the engine’s compression and combustion processes.

Use in Cylinder Block Kits

In cylinder block kits and cylinder short blocks, the expansion plug is employed to fill and seal any unnecessary openings. This is particularly important in maintaining the structural integrity of the block and preventing any fluid contamination within the engine’s compartments.

Role in Engine and Cylinder Assemblies

Within the broader engine and cylinder assemblies, the expansion plug contributes to the overall sealing strategy. It works in conjunction with other sealing components to ensure that the engine operates within optimal parameters, free from leaks that could lead to performance degradation or failure.

Importance in Service and Hardware Kits

In block service kits and block hardware kits, the expansion plug is a standard component. It is used during engine rebuilds or repairs to ensure that all passages are correctly sealed, contributing to the engine’s longevity and reliability.

Application in Specific Engine Models

For engines like the Ford Dealer models, the expansion plug is a critical component in the maintenance and repair processes. It ensures that the engine block is properly sealed, which is essential for the engine’s performance and durability.

Conclusion

In summary, the expansion plug (part 3900687) is a fundamental component in various engine systems, playing a key role in sealing and maintaining the integrity of engine blocks and related assemblies. Its proper installation and maintenance are essential for the efficient and reliable operation of the engine.