Does a 5.9 Valve Cover Fit in a 6.7? A Complete Guide to Compatibility and Engine Parts

Introduction

If you’ve ever asked, “Does a 5.9 valve cover fit in a 6.7?” you’re not alone. Many truck enthusiasts and DIY mechanics wonder if they can use parts from one engine model on another. Specifically, in the case of Cummins diesel engines, is it possible to use a 5.9L valve cover on a 6.7L engine? In this article, we’ll explore Does a 5.9 valve cover fit in a 6.7 engine and why getting the correct parts for your engine is essential.

The Basics: Understanding the 5.9 and 6.7 Cummins Engines

Before discussing Does a 5.9 valve cover fit in a 6.7, let’s examine the 5.9L and 6.7L Cummins engines. Diesel truck owners love both engines for their reliability and performance, but critical differences impact how parts fit together.

For years, the 5.9L engine was the standard in many Dodge Ram trucks, offering excellent power and efficiency. The 6.7L Cummins engine, however, is a newer, more powerful option designed to meet modern emission standards and provide improved towing capabilities. But does that mean the parts, such as the valve covers, are interchangeable?

Does a 5.9 Valve Cover Fit in a 6.7?

So, the million-dollar question is, does a 5.9 valve cover fit in a 6.7? Unfortunately, the answer is no. While the engines are part of the same family, the 6.7L engine significantly differs from the 5.9L in several key areas. Here are the main reasons why a 5.9 valve cover doesn’t fit in a 6.7 engine:

Size Differences

The 6.7L Cummins engine is physically more significant than the 5.9L engine. This increased size affects the valve cover. The 5.9 valve cover was designed to fit a smaller engine, and due to the size difference, it just won’t fit properly on the 6.7. So, a 5.9 valve cover only fits a 6.7 simply because the cover won’t align with the more significant engine components.

Bolt Patterns and Mounting Points

Another reason does a 5.9 valve cover doesn’t fit in a 6.7 engine is the difference in bolt patterns. The 5.9 engine has a different bolt placement for the valve cover than the 6.7. This means that even if you tried to force the 5.9 covers onto the 6.7 engine, it wouldn’t align with the bolt holes, leading to an improper seal and possibly damaging the engine.

Emissions Components and Design Changes

The 6.7 engine has more advanced emissions systems, such as the Diesel Particulate Filter (DPF) and Selective Catalytic Reduction (SCR). These systems require a valve cover specifically designed for the 6.7 engine. Since the 5.9 engine does not have these systems, the valve cover for the 5.9 engine is not intended to accommodate these components. Therefore, a 5.9 valve cover does not fit a 6.7 because it was never built with these extra components in mind.

What Happens if You Try to Use a 5.9 Valve Cover on a 6.7?

If you’re still asking yourself, “Does a 5.9 Valve Cover be used on a 6.7?” consider the consequences of trying. Attempting to install a 5.9 valve cover on a 6.7 engine could lead to severe issues.

Oil Leaks: The most immediate concern would be oil leaks. If the valve cover doesn’t seal properly because the bolt holes don’t line up, the oil will leak, and you’ll end up with a mess under your hood.

Engine Damage: An ill-fitting valve cover could damage other engine components, such as the cylinder head or valve seals.

Reduced Engine Performance: The valve cover helps maintain proper pressure and oil distribution. If the cover is not sealed correctly, it could lead to poor engine performance or even cause engine misfires.

Is It Worth Modifying a 5.9 Valve Cover for a 6.7?

Some people may consider modifying a 5.9 valve cover to fit their 6.7 engine, but this comes with significant risks. Does a 5.9 valve cover fit in a 6.7? While it’s technically possible to modify the cover, it’s not recommended.

Complex Modifications: You would have to drill new holes, alter the shape of the valve cover, and possibly add custom mounting points. These modifications require extensive expertise and could compromise the cover’s structural integrity.

Costly and Time-Consuming: The time and tools needed to make these modifications would likely cost you more than simply purchasing the correct valve cover for your 6.7 engine.

Risk of Failure: Even after modifying the valve cover, improper sealing or oil leaks remain. This could lead to engine damage and expensive repairs down the line.

So, while it may be tempting to answer ” yes ” to the question of whether a 5.9 valve cover fits in a 6.7, modifications to make it fit aren’t worth the risk.

Why Using the Right Valve Cover Matters

You might be wondering why using the correct valve cover for your engine is so important. The answer lies in the valve cover’s critical role in your engine’s performance.

• Prevents Oil Leaks: The valve cover creates a seal to ensure the engine oil stays inside the engine and doesn’t leak out.
• Protects the Engine: The valve cover helps regulate pressure within the engine, ensuring efficient and smooth operation.
• Ensures Proper Ventilation: The valve cover allows for proper ventilation of the engine’s internal components, which helps keep your engine cool and functioning properly.

In short, using the wrong valve cover, such as making a 5.9 valve cover fit in a 6.7, could result in many problems, from oil leaks to reduced engine performance.

The Right Way to Proceed

Instead of using a 5.9 valve cover on a 6.7 engine, it’s better to source the correct valve cover designed for the 6.7L Cummins engine. Here are some suggestions:

Buy the Correct Part: The simplest and most effective solution is to purchase a 6.7 valve cover. It’s designed specifically for your engine’s needs and will ensure a proper fit.

Consult Experts: If you need clarification on part compatibility, it’s always a good idea to consult a mechanic or diesel engine expert who can guide you.

Do Your Research: Before purchasing a valve cover, double-check that it’s compatible with the 6.7 engine. Some parts may look similar but might not work with your specific model.

Conclusion

So, does a 5.9 valve cover fit in a 6.7? As we’ve discussed, the answer is no. The 5.9 engine’s size, design, bolt patterns, and emissions systems differ from those of the 6.7 engine, making a 5.9 valve cover incompatible with the 6.7.

Attempting to use a 5.9 valve cover on a 6.7 engine may lead to oil leaks, engine damage, and other performance issues. The best solution is to use the correct valve cover designed for the 6.7 engine. This will ensure proper sealing, optimal engine performance, and long-term reliability.