3955393
Valve Stem Seal
Cummins®

Introduction

Valve stem seals are critical components in the operation of commercial truck engines, ensuring efficient and reliable engine performance. The 3955393 Valve Stem Seal by Cummins is engineered to meet the rigorous demands of heavy-duty applications, contributing to the overall efficiency, performance, and longevity of truck engines.

Basic Concepts of Valve Stem Seals

Valve stem seals are components that fit around the valve stem in an engine. Their primary function is to prevent oil from leaking into the combustion chamber while allowing the valve to move freely. This is achieved through a combination of materials and design that create a seal that is both durable and flexible. Commonly, valve stem seals are made from materials such as rubber, PTFE (polytetrafluoroethylene), or a combination of both, chosen for their ability to withstand high temperatures and pressures while maintaining a tight seal. The engineering principles behind their design focus on balancing the need for a tight seal with the requirement for minimal friction to ensure smooth valve operation ¹.

Purpose of the 3955393 Valve Stem Seal

The 3955393 Valve Stem Seal by Cummins plays a specific role in the operation of a truck engine by preventing oil leakage into the combustion chamber. This seal contributes to engine efficiency by ensuring that oil does not burn during combustion, which could lead to increased emissions and decreased fuel efficiency. Additionally, by maintaining a clean combustion environment, the seal helps to protect other engine components from contamination, thereby enhancing engine performance and longevity ².

Key Features

The 3955393 Valve Stem Seal is distinguished by its design and the materials used in its construction. It is engineered to provide a reliable seal under the high-stress conditions typical of commercial truck engines. The seal is made from high-quality materials that offer resistance to wear and thermal degradation, ensuring durability and consistent performance. Unique attributes of this seal include its precision-engineered design, which allows for optimal sealing performance without compromising valve movement.

Benefits

Utilizing the 3955393 Valve Stem Seal in truck engines offers several benefits. These include improved engine performance due to reduced oil contamination in the combustion chamber, increased durability thanks to the seal’s robust construction, and enhanced reliability, ensuring that the engine operates smoothly and efficiently over its lifespan. The seal’s design also contributes to lower maintenance requirements, making it a cost-effective solution for engine maintenance ³.

Troubleshooting and Maintenance

Common issues associated with valve stem seals include oil leaks into the combustion chamber, which can manifest as blue smoke from the exhaust or decreased engine performance. Diagnosing these issues involves inspecting the seals for signs of wear or damage and checking for oil contamination in the combustion chamber. Regular maintenance practices, such as checking the condition of the valve stem seals during routine engine servicing, can help ensure their longevity and performance. Replacing worn or damaged seals promptly is recommended to prevent further engine damage.

About Cummins

Cummins Inc. is a global power leader that designs, manufactures, and distributes engines, filtration, and power generation products. With a history of innovation and quality, Cummins has established itself as a trusted name in the commercial truck industry. The company’s commitment to quality, innovation, and customer satisfaction is evident in the design and manufacture of its engine components, including the 3955393 Valve Stem Seal. Cummins’ focus on engineering excellence ensures that its products meet the rigorous demands of heavy-duty applications, providing reliable performance and durability.

Valve Stem Seal Fitment for Cummins Engines

The Valve Stem Seal part number 3955393, manufactured by Cummins, is designed to fit a variety of their engine models. This seal is crucial for maintaining the integrity of the engine by preventing oil from leaking past the valve stems. Below is a detailed description of the engines this part fits, grouped where applicable for clarity.

B Series Engines

• B4.5 CM2350 B129B
• B4.5 RGT
• B5.6 CM2670 B152B
• B6.7 CM2350 B135B
• B6.7 CM2670 B153B
• B6.7 CM2670 B164C
• B6.7 G CMOH6.0 B125

F Series Engines

• F3.8 CM2350 F120B
• F3.8 CM2350 F128C
• F3.8 CM2620 F137B
• F3.8 F102
• F4.5 CM2620 F139B
• F4.5 CM2620 F141C

D Series Engines

• D4.0 CM2620 D103B

ISB Series Engines

• ISB (Chrysler)
• ISB CM2150
• ISB CM550
• ISB CM850
• ISB/ISD4.5 CM2150 B119
• ISB/ISD6.7 CM2150 SN
• ISB4.5 CM2350 B104
• ISB5.9 CM2880 B110
• ISB5.9 CM2880 B140
• ISB5.9 CM2880 B149

This valve stem seal is engineered to ensure a tight fit and effective sealing in all the mentioned engines, contributing to the overall performance and longevity of the engine by preventing oil leaks and maintaining proper lubrication.

Role of Part 3955393 Valve Stem Seal in Engine Systems

The 3955393 Valve Stem Seal is integral to maintaining the efficiency and performance of various engine components. It ensures a proper seal between the valve stem and the cylinder head, preventing the escape of combustion gases. This seal is particularly important in the following components:

• Camshaft: The Valve Stem Seal works in conjunction with the camshaft to ensure that the valves open and close at the correct times, maintaining engine timing and efficiency.

• Complete Engine Gasket Kit: When using a complete engine gasket kit, the Valve Stem Seal complements the gaskets by providing an additional layer of sealing, especially around the valve stems.

• Connecting Rod and Piston: Efficient sealing around the valve stem allows for better combustion, which in turn enhances the performance of the connecting rod and piston by ensuring consistent power delivery.

• Cylinder 6B Head and Cylinder Head: The seal is vital in these components to maintain compression and prevent leaks, which can lead to reduced engine performance.

• Exhaust Valve Kit and Intake Valve Kit: These kits rely on the Valve Stem Seal to ensure that the valves operate within a sealed environment, optimizing airflow and combustion efficiency.

• Full Engine Gasket Set and Upper Engine Gasket Set: These sets often include provisions for Valve Stem Seals to ensure comprehensive sealing throughout the engine.

• Gasket Kit and Head, Cylinder: The Valve Stem Seal is a key component in these kits, ensuring that the head and cylinder maintain optimal pressure and performance.

• Injector and Injector Plumbing: Proper sealing around the valve stem ensures that the injectors operate in an environment with consistent pressure, enhancing fuel delivery and combustion.

• Long Block and Long Block Kit: In these assemblies, the Valve Stem Seal is essential for maintaining the integrity of the upper engine components, ensuring that the long block performs as intended.

• Overhaul Kit: During an engine overhaul, the Valve Stem Seal is a critical component to replace, ensuring that the engine returns to optimal condition post-overhaul.

• Seal Kit and Service Kit: These kits often include Valve Stem Seals to ensure that all sealing surfaces within the engine are addressed, promoting longevity and performance.

• Parts and Performance: High-performance engines rely on precise sealing to maximize efficiency. The Valve Stem Seal plays a significant role in this by ensuring that combustion gases are contained, leading to improved performance metrics.

Conclusion

In summary, the 3955393 Valve Stem Seal is a fundamental component in various engine systems, contributing to the overall efficiency, performance, and longevity of the engine. Its role in preventing oil leaks, maintaining compression, and ensuring proper valve operation makes it an essential part of engine maintenance and performance optimization.