3944679
Connecting Rod Cap Screw
Cummins®

The 3944679 Connecting Rod Cap Screw, manufactured by Cummins, is a specialized component designed for use in commercial trucks. Cummins, a well-established name in the automotive industry, is renowned for its high-quality engine components. This part is integral to the engine’s operation, ensuring the reliable performance of commercial trucks under various operating conditions.

Basic Concepts of Connecting Rod Cap Screws

A Connecting Rod Cap Screw is a fastener used in internal combustion engines to secure the connecting rod cap to the connecting rod. This screw plays a role in maintaining the structural integrity of the engine by ensuring that the connecting rod and cap remain firmly attached. This attachment is vital for the proper operation of the engine, as it allows for the efficient transfer of force from the piston to the crankshaft during the power stroke ¹.

Role of the 3944679 Connecting Rod Cap Screw in Truck Operation

The 3944679 Connecting Rod Cap Screw is specifically designed to operate within the engine of a commercial truck. It secures the connecting rod cap, which, in turn, connects the piston to the crankshaft. This connection is fundamental for the conversion of linear motion from the piston into rotational motion for the crankshaft. The screw’s precise fit and strong fastening capability are crucial for withstanding the high stresses and vibrations encountered in truck engines.

Key Features of the 3944679 Connecting Rod Cap Screw

The 3944679 is crafted from high-strength materials, ensuring durability and resistance to wear and tear. Its design specifications include a specific thread pitch and length tailored to the requirements of Cummins engines. Additionally, the screw may feature unique attributes such as a corrosion-resistant coating, enhancing its performance in harsh operating environments.

Benefits of Using the 3944679 Connecting Rod Cap Screw

Utilizing the 3944679 in commercial truck engines can lead to improved engine reliability, durability, and performance. Its high-strength material composition and precise engineering contribute to the screw’s ability to withstand the demanding conditions of truck operation. This results in reduced maintenance requirements and enhanced engine longevity.

Troubleshooting and Maintenance Suggestions

Common issues with Connecting Rod Cap Screws may include loosening due to engine vibrations or corrosion. Regular inspection and torque checks are recommended to ensure the screws remain securely fastened. In cases where corrosion is detected, cleaning and reapplying a protective coating can help prevent further degradation. Should a screw show signs of damage or excessive wear, prompt replacement is advised to maintain engine integrity.

Installation and Replacement Procedures

For the installation or replacement of the 3944679, it is important to follow a systematic approach. Begin by ensuring the engine is cool and disconnected from any power source. Use the appropriate tools to remove the old screw, taking care not to damage the connecting rod or cap. When installing the new screw, apply the manufacturer’s recommended torque specifications to ensure a secure fit without overtightening, which could lead to damage.

Cummins: A Brief Overview

Cummins Inc. is a global power leader that designs, manufactures, and distributes engines, filtration, and power generation products. With a history spanning over a century, Cummins has established a reputation for quality, innovation, and reliability in the commercial truck industry. The company’s commitment to excellence is reflected in its wide range of products, designed to meet the demanding requirements of commercial applications.

Compatibility with Cummins Engines

The Cummins Connecting Rod Cap Screw part number 3944679 is designed to secure the connecting rod cap to the crankshaft. This screw ensures the stability and proper functioning of the engine by maintaining the alignment and tension of the connecting rod. The following Cummins engines are compatible with this part:

ISC Series Engines

• ISC CM554
• ISC CM850
• ISC8.3 CM2250

ISL Series Engines

• ISL CM2150
• ISL CM554
• ISL G CM2180
• ISL9 CM2150
• ISL9 CM2250
• ISL9.5 CM2880 L138

L Series Engines

• L GAS PLUS CM556
• L8.9
• L8.9 CM2670 L134C
• L8.9 L121
• L8.9G CMOH2.0 L125B
• L9 CM2670 L128B
• L9.3 L105
• L9.5 L117

QSC and QSL Series Engines

• QSC8.3 CM2880 C102
• QSC8.3 CM850 (CM2850)
• QSC9 CM2250 / QSL9 CM2250

G Series Engines

• G8.3
• G8.3 CM558

GTA Series Engines

• GTA8.3 CM558

6C Series Engines

• 6C8.3

The 3944679 is engineered to fit seamlessly with these engines, ensuring reliable performance and longevity. Each engine model listed above relies on this screw to maintain the integrity of the connecting rod assembly, which is essential for the smooth operation of the engine.

Role of Part 3944679 Connecting Rod Cap Screw in Engine Systems

The 3944679 Connecting Rod Cap Screw is an essential component in the assembly and functionality of various engine systems. It plays a significant role in securing the connecting rod cap to the connecting rod, ensuring the stability and integrity of the engine’s moving parts.

Integration with Key Engine Components

1. Connecting Rod and Piston Assembly:

   • The connecting rod cap screw is vital in the connecting rod and piston assembly. It ensures that the connecting rod cap is firmly attached to the connecting rod, allowing for smooth and efficient transfer of motion from the piston to the crankshaft.

2. Cylinder Block and Cylinder Head:

   • Within the cylinder block, the connecting rod cap screw helps maintain the alignment and balance of the connecting rod as it moves up and down. This is particularly important in ensuring that the piston moves smoothly within the cylinder, interacting correctly with the cylinder head during the combustion process.

3. Engine Assembly Piston and Engine Connecting Rod:

   • In a complete engine assembly, the screw secures the connecting rod cap, which in turn connects the piston to the crankshaft. This setup is fundamental for the reciprocating motion of the piston, driven by the combustion events in the cylinder.

4. Short Block and Long Block Configurations:

   • Whether dealing with a short block (engine block, crankshaft, pistons, and connecting rods) or a long block (includes cylinder head and valve train), the connecting rod cap screw is a key fastener. It ensures that the lower end of the engine remains robust and capable of withstanding the high stresses and forces generated during operation.

5. Overhaul Kit and Repair Kit:

   • During engine overhauls or repairs, the connecting rod cap screw is often included in overhaul kits and repair kits. It ensures that the newly installed or repaired connecting rod assemblies are securely fastened, contributing to the engine’s reliability and performance post-overhaul.

6. Performance Parts and On Board Spares:

   • In high-performance engine builds, the connecting rod cap screw may be upgraded for additional strength and reliability. On board spares often include this screw to ensure that any issues with the connecting rod assembly can be quickly addressed without requiring a full engine teardown.

Interaction with Fuel System Components

• Although the connecting rod cap screw primarily interacts with the mechanical components of the engine, its proper installation and maintenance indirectly support the efficient operation of fuel system components like the fuel injector, fuel manifold, and injector plumbing. A well-maintained engine assembly ensures that the fuel system operates within the designed parameters, contributing to overall engine performance and efficiency ².

Conclusion

The 3944679 Connecting Rod Cap Screw is a critical component in the operation and maintenance of Cummins engines. Its role in securing the connecting rod cap ensures the stability and efficiency of the engine’s moving parts. Proper installation, maintenance, and understanding of its integration with other engine components are essential for the reliable performance of commercial truck engines.