Can a 5.9 Valve Cover Fit on a 6.7 Cummins Engine? Find Out Here!

When upgrading or modifying your Cummins engine, you might wonder if a 5.9L valve cover can fit on a 6.7L Cummins engine. While these two engine models share similarities, there are key differences to consider. This guide provides clarity on compatibility, necessary modifications, and essential considerations.

Compatibility of 5.9L and 6.7L Valve Covers

The valve cover of a late-model 5.9 Cummins engine can fit on a 6.7L Cummins engine, but the swap isn’t a direct plug-and-play process. Some key components and modifications are necessary to ensure proper installation and functionality.

Required Modifications for Valve Cover Swap

1. Breather and Oil Drain Tubes
   • The 6.7L Cummins engine features a unique crankcase ventilation system. To use a 5.9 valve cover, you’ll need to source breather tubes and oil drain tubes from the 5.9L engine. These components are essential to maintaining proper ventilation and oil circulation.
2. Crankcase Pressure Sensor
   • The 6.7L Cummins valve cover includes a crankcase pressure sensor not present in the 5.9L cover. You can handle this in two ways:
     • Relocate the sensor by securing it outside the valve cover.
     • Modify the 5.9 valve cover to integrate the sensor, ensuring the system remains functional.
3. Crankcase Ventilation System (CCV)
   • The CCV system on a 6.7L Cummins differs significantly from the 5.9L setup. Without proper adjustments, the swap could lead to issues like oil misting or pressure buildup. Rerouting the CCV system correctly is crucial for maintaining engine performance.

Benefits and Drawbacks of the Swap

Benefits:

• Aesthetic upgrade: The 5.9 valve cover offers a sleeker, more compact design.
• Easier maintenance: The simpler design of the 5.9 cover can make access to engine components easier.

Drawbacks:

• Loss of OEM functionality: Modifying or relocating the crankcase pressure sensor may impact the engine’s monitoring system.
• Potential emissions issues: Altering the valve cover and ventilation systems can lead to non-compliance with EPA regulations.

Expert Tips for a Successful Installation

• Use OEM Parts: Stick to original Cummins components to ensure quality and compatibility.
• Consult a Specialist: A professional mechanic or Cummins specialist can provide insights and help with proper installation.
• Test for Leaks: After installation, thoroughly test the system for leaks or pressure irregularities.
• Understand Emissions Regulations: Modifications that affect the crankcase ventilation system may impact your vehicle’s emissions compliance, especially in states with stringent testing protocols.

Is the Swap Worth It?

While the swap is feasible, it’s not without its challenges. The 5.9 valve cover offers aesthetic and practical benefits, but it requires careful modifications to function on a 6.7L Cummins. For most drivers, the swap is ideal for customization enthusiasts or those seeking a specific look for their engine bay.

Conclusion

Swapping a 5.9 valve cover onto a 6.7 Cummins engine is a viable option, provided you’re willing to address the necessary modifications and potential drawbacks. By understanding the requirements and ensuring a professional installation, you can enjoy the benefits of this upgrade while maintaining your engine’s performance and reliability.

• Can a 5.9L valve cover fit on a 6.7L Cummins engine?
  Yes, a 5.9L valve cover can fit on a 6.7L Cummins engine, but it requires specific modifications and additional components.
• What modifications are needed to fit a 5.9 valve cover on a 6.7 Cummins?
  You’ll need to address the crankcase pressure sensor, reroute the crankcase ventilation system, and use 5.9L breather and oil drain tubes.
• Does the crankcase pressure sensor need to be relocated?
  Yes, the 6.7L crankcase pressure sensor must either be secured outside the 5.9 valve cover or integrated into the cover with modifications.
• Are there any potential issues with swapping the valve covers?
  Yes, issues like oil misting, improper ventilation, or non-compliance with emissions regulations can arise if the swap isn’t done correctly.
• Is it better to use OEM parts for this swap?
  Absolutely. Using OEM components ensures proper fitment, quality, and compatibility with your engine.
• What are the main benefits of using a 5.9 valve cover on a 6.7 Cummins?
  The swap offers a sleeker aesthetic and easier maintenance access, though it requires careful adjustments.