3678921
Threaded Plug

2 Pack

Cummins®

The Cummins 3678921 Threaded Plug is a component designed for use in commercial trucks. It serves a specific function within the truck’s system, contributing to the overall efficiency and reliability of the vehicle. Understanding its purpose and application is key to maintaining and optimizing truck performance.

Basic Concepts of Threaded Plugs

Threaded plugs are mechanical components used to seal openings in various systems. They function by being screwed into place, creating a secure seal that prevents leaks and maintains system pressure. In automotive applications, threaded plugs are commonly used in engine blocks, transmission cases, and other areas where sealing is necessary ¹.

Purpose and Function of the 3678921 Threaded Plug

The Cummins 3678921 Threaded Plug plays a role in the truck’s system by providing a seal in specific applications. It helps in managing pressure within the system and ensures the integrity of the system by preventing leaks. This plug is integral to maintaining the operational efficiency of the truck by ensuring that fluids and gases remain contained within their designated pathways ².

Key Features

The Cummins 3678921 Threaded Plug is characterized by several key features that enhance its performance and durability. These include its material composition, which is designed to withstand the harsh conditions within a truck’s engine compartment. The thread type is also specifically engineered to ensure a tight and secure fit, while the design specifications are tailored to meet the demands of commercial truck applications ³.

Benefits

The advantages of using the Cummins 3678921 Threaded Plug include improved system reliability due to its secure sealing capabilities. It also offers ease of installation, which can reduce downtime during maintenance procedures. Additionally, the durability of the plug contributes to long-term cost savings by minimizing the need for frequent replacements ⁴.

Troubleshooting and Maintenance

Common issues with threaded plugs may include leaks or difficulty in removal due to corrosion. To diagnose these problems, it is important to inspect the plug and the surrounding area for signs of wear or damage. Regular maintenance practices, such as cleaning the threads and applying the appropriate lubricant during installation, can help ensure the optimal performance and longevity of the Cummins 3678921 Threaded Plug .

About Cummins

Cummins Inc. is a global power leader that designs, manufactures, and distributes a wide range of power solutions. With a history spanning over a century, Cummins has established a strong reputation in the commercial truck industry for producing reliable and high-performance engines and components. The company’s product range includes engines, filtration systems, and other critical components that are essential for the operation of commercial vehicles.

Threaded Plug 3678921 Compatibility with Cummins Engines

The Threaded Plug 3678921, manufactured by Cummins, is a versatile component designed to fit a variety of Cummins engines. This plug is integral for sealing and securing various parts within the engine system, ensuring optimal performance and safety.

Compatible Engines

• 15N CM2380 M104B
• 6B5.9
• 6C8.3
• B4.5 RGT
• B5.6 CM2670 B152B
• B5.9 G
• B5.9 GAS PLUS CM556
• B6.7 CM2350 B135B
• B6.7 CM2670 B153B
• B6.7 CM2670 B164C
• B6.7 G CMOH6.0 B125
• B6.7S
• C GAS PLUS CM556
• F2.8 CM2620 F135B
• F3.8 CM2350 F128C
• F3.8 CM2620 F137B
• F3.8 F102
• F4.5 CM2620 F139B
• F4.5 CM2620 F141C
• G5.9
• G5.9 CM558
• G8.3
• G8.3 CM558
• GTA38 G CMEICS G116C
• GTA8.3 CM558

Grouping of Compatible Engines

Group 1: B Series Engines

• B4.5 RGT
• B5.6 CM2670 B152B
• B5.9 G
• B5.9 GAS PLUS CM556
• B6.7 CM2350 B135B
• B6.7 CM2670 B153B
• B6.7 CM2670 B164C
• B6.7 G CMOH6.0 B125
• B6.7S

Group 2: F Series Engines

• F2.8 CM2620 F135B
• F3.8 CM2350 F128C
• F3.8 CM2620 F137B
• F3.8 F102
• F4.5 CM2620 F139B
• F4.5 CM2620 F141C

Group 3: G Series Engines

• G5.9
• G5.9 CM558
• G8.3
• G8.3 CM558

Group 4: GTA Series Engines

• GTA38 G CMEICS G116C
• GTA8.3 CM558

Group 5: Other Models

• 15N CM2380 M104B
• 6B5.9
• 6C8.3
• C GAS PLUS CM556

This detailed grouping helps in understanding the broad compatibility of the Threaded Plug 3678921 across different engine series and models.

Role of Part 3678921 Threaded Plug in Engine Systems

The threaded plug, identified as part 3678921, serves a significant function in various engine systems by ensuring the integrity and efficiency of the components it interfaces with. Here’s how it integrates with several key engine components:

• Air Intake Connection Location: The threaded plug secures the air intake system, preventing air leaks that could affect engine performance and efficiency.

• Alternative Design: In engines with alternative designs, the threaded plug may be used to seal off unused ports or passages, ensuring that the engine operates within its designed parameters without interference from external elements.

• Auxiliary Cooling Inlet Connection: It plays a role in sealing the auxiliary cooling inlet, maintaining the proper flow of coolant to critical engine components, thus aiding in temperature regulation.

• Block, Short Euro1: Within the short Euro1 block, the threaded plug is utilized to seal off specific passages or ports, contributing to the block’s structural integrity and operational efficiency.

• Cylinder Block Lubrication Plumbing: The plug ensures that the lubrication system within the cylinder block remains sealed, preventing oil leaks and maintaining consistent lubrication to moving parts.

• Electronic Control Module Wiring Harness: It secures connections within the wiring harness, protecting electronic components from moisture, debris, and electrical shorts.

• Engine Oil Primer Plumbing: In the engine oil primer system, the threaded plug ensures that the priming process is efficient, without leaks, facilitating proper engine lubrication upon startup.

• Filter Shell and Gas Mixers: It seals components within the filter shell and gas mixers, ensuring that the air-fuel mixture is correctly metered and delivered to the engine.

• Flywheel Housing Kit: The plug is used to seal the flywheel housing, preventing contaminants from entering and ensuring the smooth operation of the flywheel and associated components.

• Fuel Pressure Regulator: It maintains the seal within the fuel pressure regulator, ensuring consistent fuel pressure is delivered to the engine.

• Fuel Pump Drive: In the fuel pump drive system, the threaded plug ensures that the drive mechanism is sealed, contributing to the efficient operation of the fuel pump.

• Fuel Shutoff Valve: The plug seals the fuel shutoff valve, ensuring that fuel flow can be precisely controlled and stopped when necessary.

• Fuel Supply Tube: It ensures the integrity of the fuel supply tube, preventing leaks and maintaining consistent fuel delivery to the engine.

• Gear Cover: The threaded plug seals the gear cover, protecting internal gear components from contamination and ensuring their longevity.

• Gear Housing: Within the gear housing, it prevents oil leaks and contamination, ensuring the gears operate smoothly and efficiently.

• Heat Exchanger: The plug seals the heat exchanger, maintaining the efficiency of heat transfer processes within the engine system.

• Lubricating Oil Filter Head: It ensures the lubricating oil filter head is sealed, preventing oil leaks and maintaining the filter’s effectiveness in cleaning the engine oil.

• Oil Cooler Kit: The threaded plug seals components within the oil cooler kit, ensuring efficient cooling of the engine oil.

• Oil Pan Plumbing: It maintains the seal within the oil pan plumbing, preventing oil leaks and ensuring the oil pan’s structural integrity.

• Plumbing: Throughout various plumbing systems within the engine, the threaded plug ensures seals are maintained, preventing leaks and ensuring fluid systems operate efficiently.

• Lub Oil Prim Pump: In the lubrication oil priming pump system, it ensures that the priming process is sealed, facilitating efficient engine lubrication upon startup.

• Priming Pump: The plug seals the priming pump, ensuring that the pump operates efficiently without leaks.

• Repair Kit: In repair kits, the threaded plug is often used to seal repaired components, ensuring the repair is effective and long-lasting.

• Short 6-B Block: Within the short 6-B block, it seals off specific passages or ports, contributing to the block’s structural integrity and operational efficiency.

• Turbocharger Coolant Plumbing: It ensures the turbocharger coolant system is sealed, maintaining efficient cooling of the turbocharger.

• Turbocharger Plumbing: The plug seals various components within the turbocharger plumbing, ensuring efficient operation and preventing leaks.

Conclusion

The Cummins 3678921 Threaded Plug is a critical component in the maintenance and optimization of commercial truck performance. Its role in sealing various engine systems ensures the integrity and efficiency of the truck’s operation. Understanding its features, benefits, and compatibility with different Cummins engines is essential for effective maintenance and troubleshooting.