Updated: May 15, 2026
If you are planning to replace the valve cover on a 6.7L Cummins diesel engine, you are already past basic bolt-on maintenance. At that point, the real question is not only whether the new cover fits, but whether the factory crankcase ventilation system still makes mechanical sense with the upgraded layout.
Quick answer: On many 6.7 Cummins valve cover upgrades, the factory CCV filter cannot be reused because it is built into the stock valve cover assembly. When you install an aftermarket aluminum valve cover without the factory internal CCV filter housing, you must reroute crankcase ventilation through an external path, usually with a catch can, oil/air separator, or properly routed breather system.
This is why many owners call the job a “CCV delete.” Technically, the better term is CCV reroute: you are deleting the stock internal filter arrangement, not deleting crankcase ventilation itself. Blow-by still needs a safe, controlled path out of the crankcase.
What the CCV System Does on a 6.7 Cummins
CCV stands for Crankcase Ventilation. Its job is to manage blow-by gases that escape past the piston rings during combustion. Those gases carry pressure, heat, oil vapor, moisture, and unburned hydrocarbons into the crankcase.
On a stock 6.7 Cummins, the factory system routes crankcase vapor through a filter element integrated into the valve cover, then sends the cleaned vapor back into the intake stream. That layout helps the truck meet factory emissions requirements, but it also means the valve cover and CCV filter are mechanically tied together.
If you want the basic definition before modifying anything, read how the system works.
Why the Factory Valve Cover and CCV Filter Are Linked
The key point is simple: on the 6.7 Cummins, the factory CCV filter is not just a small external service part sitting beside the valve cover. It is part of the factory valve cover architecture. Oil separation, pressure routing, and vapor return are built into that assembly.
Once the factory cover is removed, the internal CCV filter path is removed with it. That is why an aftermarket Cummins valve cover upgrade must be paired with a new crankcase ventilation strategy.
The bottom line: You are not deleting crankcase ventilation. You are deleting the factory internal CCV filter layout and replacing it with an external routing system.
Why Aftermarket Valve Covers Use External Venting
Aftermarket aluminum valve covers are typically designed around a stronger housing with external ports. Instead of forcing crankcase vapor through the factory internal filter cavity, the cover gives you a direct path to route vapor into an external separator, catch can, or breather system.
This approach gives builders more control over:
- Crankcase pressure relief
- Oil mist separation
- Vent hose routing
- Service access
- Intake contamination control
- Future maintenance around the upper engine
For this reason, the first category to compare is the Cummins CCV delete and reroute kit collection.
The Pressure Problem: Why a Saturated CCV Filter Becomes a Bottleneck
A stock CCV filter is a porous media element. When it is clean, crankcase vapor can pass through with manageable restriction. When it becomes saturated with oil mist, soot residue, and moisture, the pressure drop across that filter increases.
From an engineering standpoint, the pressure drop across the factory CCV filter can be simplified as:
ΔP = Pbefore filter - Pafter filter
As blow-by volume rises under heavy towing, high boost, or high-mileage ring wear, the crankcase has to vent more gas. If the filter is saturated, the ventilation rate becomes restricted. That raises static crankcase pressure and pushes harder against sealing points such as the valve cover gasket, front main seal, rear main seal, dipstick tube area, and turbo drain path.
In plain language: the factory CCV filter is supposed to relieve pressure, but once it becomes restrictive, it can become part of the leak problem.
Mechanical Reasons to Reroute the Stock CCV System
1. Cleaner Intake Air
The factory CCV system sends crankcase vapor back into the intake. That vapor contains oil mist. Over time, the oil coats charge pipes, intercooler boots, turbo inlet surfaces, compressor blades, intake horns, and manifold passages.
When oily mist passes through the turbocharger compressor wheel, it does not just reduce intake cleanliness. It collects at the low points of the charge-air system and can soften, swell, or weaken silicone boots over time. Under heavy boost, contaminated intercooler boots are more likely to slip, leak, or blow off under load.
Keeping oil vapor out of the intake helps protect the Cummins intake manifold and intake horn from oil saturation and sludge buildup.
2. Better Crankcase Pressure Control
Blow-by pressure has to go somewhere. If the factory CCV filter becomes saturated or restrictive, crankcase pressure can rise. When pressure builds, it may look for weak points: valve cover gasket edges, front and rear main seals, dipstick tube areas, or turbo drain paths.
A properly routed external CCV system gives pressure a controlled exit path. That is especially useful on higher-mileage trucks, towing trucks, or engines that see sustained load.
3. Less Oil Sludge in the Intake
Oil vapor alone is messy. When it mixes with EGR soot, it becomes sticky carbon sludge. That sludge can build up in the intake tract, throttle valve area, charge piping, and sensor passages. This is why CCV management and EGR soot control are often discussed together by diesel owners.
A good separator or catch can does not make the engine maintenance-free, but it removes one of the main ingredients that turns dry soot into black paste.
4. Easier Service Access
The stock CCV housing takes up space on top of the engine. Removing the bulky factory arrangement can improve access around the upper engine, injector wiring area, and valve cover perimeter. This does not turn the rear of the engine into open space, but it does simplify the layout compared with the factory cover.
5. Better Long-Term Valve Cover Sealing
Many owners upgrade to aluminum valve covers because old composite covers can warp, crack, or leak after years of heat cycling. A billet or cast aluminum cover can provide a more stable sealing surface when installed correctly.
For a direct product option, review the SPELAB aluminum valve cover for 6.7 Cummins.
Real-World Example: 6.7 Cummins Valve Cover Upgrade
A 2014 Ram 2500 6.7L Cummins owner documented the move from the OEM valve cover setup to an aftermarket aluminum cover. This kind of build shows why CCV rerouting becomes part of the job: once the factory cover is gone, the integrated CCV filter and internal routing are gone too.
Technical Breakdown of the Upgrade
1. Plastic Fatigue vs. Aluminum Stability
The issue: The factory composite valve cover can become brittle or distorted after years of thermal cycling. Once the sealing surface loses stability, oil leaks can appear around the perimeter or rear of the engine.
The fix: An aluminum valve cover gives the gasket a more stable clamping surface, assuming the cover is machined correctly and installed with the proper gasket and torque sequence.
2. Injector Harness and Gasket Area
The issue: On the 6.7 Cummins, injector wiring and gasket sealing are part of the upper-engine service picture. Any leak path through or around the cover becomes frustrating because access is tight.
The fix: A simplified aftermarket cover can reduce the number of internal oil-vapor passages inside the cover. That does not eliminate every leak risk, but it does simplify the sealing job and improves visibility around the upper engine.
3. Removing the Saturated Filter Problem
The issue: A saturated CCV filter can contribute to crankcase pressure and “Perform Service” reminders on certain 6.7 Cummins applications. A properly designed reroute removes the factory filter restriction and replaces it with a serviceable external system.
4. DTCs and Symptoms to Watch
Depending on year and calibration, owners may see crankcase ventilation or airflow-related symptoms such as a “Perform Service” message, P1487-style crankcase ventilation restriction faults, or secondary airflow/boost plausibility codes such as P0106 or P0299 when oil contamination contributes to intake or boost-system problems. Always diagnose codes by platform, not by code number alone.
If you are unsure whether your current problem is the valve cover, gasket, or crankcase pressure, read how to diagnose the leak source.
Open Breather vs. Sealed Catch Can: Which Is Better?
This is where many owners make the wrong call. A simple open breather may relieve pressure, but it can also create oil smell, mist residue, and emissions concerns depending on how the truck is used and where it is registered.[1]
| Setup | Pros | Cons | Best Use Case |
|---|---|---|---|
| Open breather | Simple pressure relief, fewer parts | Oil smell, mist residue, possible compliance concerns | Off-road or competition setups where permitted |
| Sealed catch can | Captures oil mist, cleaner engine bay, better street manners | Needs periodic draining and correct routing | Daily-driven and towing trucks |
| Oil/air separator | Best balance of vapor control and pressure management | More planning required for hose routing | Higher-mileage or upgraded trucks |
For daily-driven trucks, the sealed system is usually the smarter path. A well-baffled catch can lets the owner upgrade the valve cover and control crankcase pressure without simply dumping oily vapor into the engine bay. For a street-friendly setup, compare the Cummins diesel oil catch can.
For a deeper explanation, read how oil separation works.
What Can Go Wrong If You Delete CCV Incorrectly?
A CCV reroute is not complicated, but it does need to be planned correctly. The goal is not just to remove a filter. The goal is to keep crankcase pressure controlled while keeping oil mist out of places it should not go.
| Problem | Likely Cause | How to Avoid It |
|---|---|---|
| Oil smell in cab | Open breather venting near HVAC intake or engine bay | Use a sealed catch can or route the vent away from the cab |
| Oil mist on frame or engine bay | No separator or poor hose routing | Install a baffled catch can or oil/air separator |
| Oil leaks | Crankcase pressure not relieved properly | Use adequate hose diameter and avoid kinked vent lines |
| Boot slip or boost leak | Oil-contaminated intercooler boots and charge pipes | Clean the charge-air system and stop oil vapor at the source |
| Condensation buildup | Short trips, cold weather, poor catch can service | Inspect the can more often in winter |
| Check engine light | Model-specific sensor or pressure routing issue | Keep required sensors connected and follow kit instructions |
For filter-service background, see factory maintenance interval.
Best Practice Setup for a 6.7 Cummins Valve Cover Upgrade
The best setup is not “remove everything and hope.” A proper 6.7 Cummins valve cover upgrade should treat the valve cover, crankcase pressure, oil mist, and intake cleanliness as one system.
- Aluminum valve cover: Replaces the factory cover and removes the integrated CCV filter housing.
- External CCV reroute: Gives blow-by gases a controlled path out of the crankcase.
- Oil catch can or separator: Captures oil mist before it coats the intake or engine bay.
- Proper hose routing: Prevents kinks, oil pooling, smell, and pressure restriction.
- Winter inspection: Checks for condensation buildup in cold climates.
- Boost-system cleanup: Removes existing oil film from boots and pipes before reassembly.
For broader fitment options, compare the billet aluminum valve cover collection.
Beginner Quick Summary
- The factory 6.7 Cummins CCV filter is built into the stock valve cover.
- Most aftermarket aluminum valve covers cannot reuse the factory internal CCV filter.
- That means crankcase ventilation must be rerouted externally.
- A catch can or oil/air separator is strongly recommended.
- The goal is pressure control, cleaner intake air, fewer oil-vapor deposits, and better upper-engine serviceability.
So, Is CCV Deletion Required?
Yes, if you are replacing the stock 6.7 Cummins valve cover with an aftermarket cover that does not include the factory internal CCV filter design. But the better way to say it is this: the factory CCV filter is deleted, and crankcase ventilation must be rerouted.
For a daily-driven truck, the smartest setup is usually not an open vent. It is an aluminum valve cover paired with a properly routed external separator or catch can. That gives you the mechanical benefits of the upgrade without turning crankcase vapor into a smell, mess, or pressure problem.
FAQ
Q：Does every 6.7 Cummins valve cover replacement require CCV deletion?
A：If the replacement valve cover does not include the factory integrated CCV filter housing, yes. The stock internal CCV filter setup must be removed, and crankcase ventilation must be rerouted externally.
Q：Is CCV deletion the same as CCV reroute?
A：Not exactly. “CCV delete” usually means deleting the stock internal filter system. “CCV reroute” is the more accurate term because blow-by gases still need a safe path out of the crankcase.
Q：Is CCV reroute safe for daily driving?
A：Yes, when it is done with proper hose routing and a catch can or oil/air separator. A simple open breather may create oil smell or mist, especially on a daily-driven truck.
Q：Will CCV deletion increase horsepower?
A：Not directly. The main benefits are cleaner intake air, reduced oil mist contamination, improved crankcase pressure control, and better long-term serviceability.
Q：Will I smell oil fumes after a CCV delete?
A：You might if the system vents openly near the engine bay or HVAC intake. A sealed catch can or properly routed vent line helps reduce fumes.
Q：Can I reuse the stock CCV filter with an aluminum valve cover?
A：Usually no. Most aftermarket aluminum valve covers do not have the internal cavity and routing needed to reuse the bulky factory CCV filter.
Q：Does a CCV reroute require ECU tuning?
A：Usually no. A mechanical CCV reroute normally does not require tuning, but model-year differences and sensor layouts matter. Always follow the kit instructions.
Q：Can a bad CCV system cause P1487?
A：On some applications, crankcase ventilation restriction can be associated with P1487-style faults or “Perform Service” reminders. Always confirm the exact code definition for your year, calibration, and scan tool.
Q：Can oil vapor cause intercooler boot problems?
A：Yes. Oil mist can coat silicone boots and charge pipes. Over time, that contamination can contribute to boot slip, swelling, softening, or boost leaks under load.
Q：How often should I service the external catch can?
A：Check it at every oil change. In cold weather, inspect it more often because condensation can fill the can faster than expected.
Legal Notes
[1] Venting crankcase emissions directly to atmosphere may create emissions-compliance issues depending on vehicle use and local regulations. In the United States, tampering with required emissions systems or installing parts that bypass or defeat emissions controls may violate the Clean Air Act. Reference: EPA Clean Air Northeast: Tampering and Aftermarket Defeat Devices.
[2] The Clean Air Act also prohibits manufacturing, selling, offering for sale, or installing aftermarket parts or devices that bypass, defeat, or render emissions controls inoperative. Always confirm federal, state, provincial, and local regulations before modifying emissions-related hardware. Reference: EPA National Enforcement and Compliance Initiative on Aftermarket Defeat Devices.
John Lee
Mechanical Engineer | 10+ Years Experience
John has spent the last decade engineering and testing high-performance automotive components. Specializing in drivetrain durability and thermal management across Powerstroke, Cummins, and Duramax applications, he bridges the gap between OEM limitations and aftermarket performance. His philosophy: "Factory parts are just a starting point."
2 comments
Doing a CCV delete and installing a Spelab Valve Cover do need to modify the cover to receive a crankcase pressure sensor for proper operations??
Hi need to exchange one of the heaters the bolt that the wire attaches to is loose will not seal thanks