What Does a CCV Reroute Do? Benefits, Risks & Guide

Have you ever taken your intercooler boots off and discovered that they are covered with a thick sticky oil? Or perhaps you have noticed your 6.7 Cummins pouring oil into the dipstick tube and have been wondering what's happening under the hood.

This stuff, this black gunk, is not dirt or residue; it is an immediate consequence of the blow-by gases being blown out of your diesel engine crankcase ventilation (CCV) system.

Blow-by gases are normal in every diesel engine, but when they combine with the oil and are forced back through your intake, they leave a coating of sludge on the turbo, intercooler, and intake manifold. This buildup may cause turbo inefficiency, increase leakages, and even disastrous engine failures over time.

So, what does a CCV reroute do?

A CCV reroute works by diverting the crankcase gases, leading to oil accumulating in your intake manifold and turbocharger, and instead it is vented out. It keeps your diesel engine clean and prevents failures like blown turbo seals or runaway engines.

Factory systems push dirty air back into the turbo for emissions, but this coats parts in sludge. A CCV reroute installation is not only a performance or cosmetic cleanliness issue. It is all about guarding your engine against blown turbo seals, too much crankcase pressure, and even diesel runaway conditions.

We see this often in our shop, and a reroute fixes it. Keep reading to learn how does CCV reroute works, its benefits, risks, kit types, and whether your diesel engine really needs one.

What Is a Crankcase Ventilation/CCV System and How Does it Work?

Your diesel engine builds pressure from blow-by gases, and without ventilation, seals blow out. This problem gets worse over time and leads to leaks.

If you're new to diesel ownership, you might be wondering what CCV means or what a CCV is on a diesel engine.

A CCV system vents these gases safely, manages blow-by, and keeps your engine from over-pressurizing. It pulls vapors out and sends them back into the intake on factory setups.

All diesel engines have the problem of blow-by, the gases of combustion passing out of the piston rings into the crankcase. When these gases are not controlled, they cause pressure that may push oil through seals and gaskets, resulting in leaks, premature wear, and damage of the engine.

A crankcase ventilation system is designed to release this pressure without compromising the running of an engine cleanly and efficiently. The CCV system also allows one to maintain the engine life by controlling blow-by gases, and unnecessary wear is minimized.

Purpose of Crankcase Ventilation

Crankcase ventilation removes gases that slip past piston rings during combustion. These gases include unburned fuel, water vapor, and oil mist. If left inside, they raise pressure and dilute oil, which harms bearings and seals.

We once saw a truck with no ventilation that blew its rear main seal after just 50,000 miles. Ventilation keeps pressure low and oil clean.

How Blow-By Gases Are Managed

While blow-by is normal, a properly designed CCV reroute is often considered a diesel blow-by fix for oil contamination issues, helping owners understand how to fix blow-by on a diesel engine before it leads to seal failure or turbo damage.

Blow-by gases contain:

• Air
• Combustion byproducts
• Oil vapor
• Moisture

The factory CCV system diverts such gases to a filter or separator that removes a part of oil and introduces partially treated air into the intake. The process can reduce emissions, yet it is not flawless.

How the Factory CCV System Works

In most diesel trucks, the stock CCV system redirects blow-by gases back into the intake tract. This keeps emissions in check but inadvertently leads to oil vapor recirculation. Over time, oil coating builds up on:

• Turbo compressor wheels
• Intercooler piping
• Intake manifolds

This pollution may reduce turbo efficiency, accelerate boost leakages, and lower the overall diesel engine life.

For the 6.7 Powerstroke, it's a black box on the valve cover; for Cummins, a top filter. Duramax uses a plastic unit. These work okay at first, but clog with miles.

We recommend checking your oil every oil change to avoid issues. <Check the maintainance guide>

Component	Function	Common Issue
Valve Cover Filter	Separates oil from gases	Clogs with soot and oil
Hose to Intake	Routes gases back	Leaks or freezes in cold
Baffle	Traps larger oil drops	Wears out over time

This setup helps emissions but hurts long-term engine health. Rerouting fixes that.

What Does a CCV Reroute Do?

Understanding what does a CCV reroute do starts with understanding how the factory CCV system works.

Oil mist from crankcase gases coats your turbo and intake, cutting boost and risking failures. This sludge builds fast in tuned trucks.

A CCV reroute redirects vapors away from the intake, separates oil mist, and prevents re-entry into the turbo and intercooler. It vents gases externally or to a catch can.

1. Redirects Crankcase Vapors Away from the Intake

A CCV reroute modifies the factory system so that blow-by gases are handled more effectively. Instead of routing crankcase vapors back into the turbo and intake, a CCV reroutes them either into a catch can or externally.

This prevents oil-laden gases from contaminating your critical engine components. We installed one on our shop truck, and the intake stayed dry after 10,000 miles. It uses hoses and fittings to vent under the truck or to exhaust.

2. Separates Oil Mist from Airflow

In a large number of reroute kits, internal baffling or catch cans are used to separate oil and the blow-by gases. The oil accumulates in the canister or is redirected safely, and only clean vapor or air is released.

This keeps 95% of oil out of the system. Without it, mist mixes with soot from EGR and forms tar.

3. Prevents Oil Re-Entry into the Turbo and Intercooler

No oil means no coating on compressor wheels or boots. Turbo spins freer, and boots last longer. In cold weather, we route hoses short to avoid freezes.

The reroute maintains turbo efficiency, eliminates intercooler contamination, and assists in keeping the engine clean, overall by preventing re-entry of oil into the intake tract. It boosts reliability, especially for towing.

Step in Reroute	Benefit	Risk if Ignored
Remove Factory Hose	Clears space	Pressure buildup
Install Billet Cap	Seals valve cover	Leaks
Add Catch Can	Collects oil	Drips on ground

Reroutes make engines run cleaner and last longer. They fit most diesels with simple tools.

Benefits of Installing a CCV Reroute

Your diesel loses power from sludge in the intake, and fixing it costs hundreds. Don't let buildup ruin your turbo. The real CCV reroute benefits go beyond cleanliness.

Installing a CCV reroute prevents turbo coating, eliminates boot failures, and stops sludge. It keeps systems clean and supports tuned setups.

While performance gains may be modest, the real advantage of a CCV reroute is diesel engine longevity.

Modern diesels produce more blow-by than ever, and factory systems are prone to contamination over time. Installing a reroute kit can prevent many common problems and improve diesel engine performance.

1. Preventing "Turbo Coating" and Efficiency Loss

Oil mist in the intake does more than look messy. It sticks on the blades of the turbo compressor, trapping soot and dust. This changes the aerodynamics of the blades over time, making boost efficiency 10-15% drop and spool time to increase.

A CCV reroute will keep the turbo bone dry, and therefore, keep air flowing and the life of the turbos lengthened. We saw a Cummins gain 2 psi boost after install.

2. Eliminating Intercooler Boot Failures

Oily intercooler boots tend to pop off under boost, particularly during heavy towing or performance driving. Silicone and rubber are degraded by oil, causing hoses to lose grip.

By preventing oil from entering the intake piping, a CCV reroute keeps intercooler boots secure and reduces the likelihood of boost leaks or unexpected failures.

No oil means boots stay dry and grip tight. Our fleet trucks stopped blowing boots after reroutes.

3. Stopping the "Sludge" (Oil + Soot = Cement)

EGR-equipped modern diesels are especially prone to sludge accumulation. The vaporized oil combines with the dry soot of the recirculated exhaust gases and creates a tar-like material that is sticky and coats through intake manifolds and charge air coolers.

The CCV recirculates the oil component, and the soot goes through the circuit as harmless dust. Benefits include:

• Cleaner intake and intercooler systems
• Improved turbo reliability
• Reduced boost leaks
• Better engine cleanliness
• Support for tuned or deleted setups. It works great with deletes.

Benefit	How It Helps	For Which Engines
Cleaner System	No oil buildup	All diesels
Turbo Reliability	Dry wheels	Powerstroke, Cummins
Reduced Leaks	Strong boots	Duramax
Better Cleanliness	Less sludge	Tuned setups

This mod saves money on repairs and boosts performance. We use it on all our deleted trucks.

Cons and Risks of a CCV Reroute: What Nobody Tells You

While a CCV reroute can dramatically improve engine reliability and prevent messy intake oil buildup, it's not without potential drawbacks.

Venting gases incorrectly can cause smells or freezes, leading to seal blows. Know the downsides before installing.

Cons include school bus smell, cold weather freezes, and oil drips. Nobody tells you these, but solutions exist.

Many diesel owners don't realize that a CCV reroute can introduce its own set of minor issues if it's not planned or installed correctly. Let's break down the three most common challenges.

1. The "School Bus Smell."

One of the first things truck owners notice when venting their CCV system to the atmosphere (open breather style) is a distinct diesel odor. At idle, especially in tight garages or driveways, the smell can be strong enough to make you think something is wrong with the engine.

This is completely normal; blow-by gases contain unburned fuel vapors and a bit of oil mist. When vented outside the intake system, the scent is noticeable. Although this will not damage your engine or truck, it can be irritating if your truck is parked close to your house or even in tight areas.

Solutions to minimize odor:

• Direct the CCV vent hose to the back of the truck, behind the axle, and fumes are likely to disappear soon.
• Install a system that captures the majority of the oil and dampens the smell and then the vapor escapes.
• In the case of ordinary drivers, a longer hose with venting down and out of the window or foot traffic can be taken into consideration.

With these simple adjustments, the "school bus smell" is mostly manageable.

We fixed this on our rig by routing a longer hose to the rear axle. Catch cans also help.

2. The Cold Weather Freeze (CRITICAL WARNING)

Diesel owners in colder climates need to pay special attention to CCV reroute hoses. The reason is simple: blow-by gases aren't just oil; they also contain water vapor. As this vapor is exposed to low temperatures within a hose of a small diameter, it tends to harden into ice, which will result in a total blockage.

Crankcase pressure can skyrocket nearly instantaneously in case the hose freezes, preventing the flow of air. This pressure has no place to go, and the outcome can be disastrous: ripped rear main seals, turbo seal failure,s or even oil spurts in several places.

Practical tips for cold-weather owners:

• Use a larger diameter hose: A minimum of 3/4" ID or ideally 1" ID reduces the chance of freezing. Smaller hoses have more chances of being ice-blocked.
• Keep a short hose: The longer the hose, the more water will be collected and frozen. Minimally continue routing.
• Internal catch can setups: Some kits, like those designed for the 6.7 Powerstroke, sit inside the engine bay or close to the valve cover. They stay warm with engine heat, preventing freeze issues entirely.

Ignoring this warning can turn a simple CCV reroute into a repair nightmare in winter. We learned this after a winter failure.

3. The "Drip" (Environmental)

When venting to the atmosphere without a catch can, some oil will inevitably exit with the blow-by gases. This will usually be in the form of little spots underneath your truck or a driveway. It is not a significant environmental risk, but it is not a good sight and may be picked up by dirt.

Solution: Install a catch can. These systems collect oil and allow you to drain it during routine maintenance, keeping your driveway clean and the environment a little happier.

Risk	Cause	Solution
Smell	Atmosphere vent	Long hose or can
Freeze	Water vapor	Large hose, short run
Drip	No collection	Add catch can

These risks are manageable with good CCV reroute kits. We avoid them by choosing quality parts from reliable performance shop like EGR Performance.

Engine-Specific Guide: Do You Need a CCV Reroute?

High miles mean more blow-by, and factory systems can't handle it. Check if your diesel needs help.

You need a CCV reroute if you have oil leaks, clogs, or high pressure. It's key for specific engines like Powerstroke or Cummins.

Not all diesel engines experience CCV issues in the same way. Here's a breakdown by popular engines:

6.7 Powerstroke (2011–2024)

The Issue: The factory "black box" crankcase ventilation filter 6.7 Powerstroke, especially from 2011–2016, is prone to clogging. Oil and sludge can back up into the intake, coating the turbo and intercooler pipes.

Even the newer 2020+ models benefit from a reroute, as the upgraded baffle-style design improves flow but doesn't eliminate oil vapor. Also helps turbo health.

The Fix:

• 2011–2016 models: Installing a CCV reroute 6.7 is almost mandatory to prevent turbo and intercooler contamination.
• 2020+ models: Rerouting is recommended to maximize turbo life and prevent minor oil buildup.

Pro Tip: Some reroute kits require sensors or tuning to prevent P04DB codes from triggering on modern ECMs. Use a tuner or sensor kit to fool the ECM. We did this in 2015 and fixed leaks.

If you're installing a reroute, check kit compatibility with your year and ECU version.

Eliminate messy oil buildup in your intercooler and extend the life of your turbo with a 6.7 Powerstroke CCV delete kit and check the reviews.

6.7 Cummins (2007.5–2024)

The Issue: 

The Cummins crankcase ventilation filter is easily saturated, which happens faster than the 67,500-mile recommended period in the manuals. Eventually, the crankcase pressure may be excessive to the extent of leaking the dipstick tube, front main seal, or valve cover gasket.

Symptoms:

• Oil dripping from the dipstick or valve cover
• Higher-than-normal oil consumption
• Noticeable turbo or intake contamination

The Fix:

• Replace the factory CCV filter with a billet breather cover.
• It is a good idea to fit a full CCV reroute kit to eliminate all the gases contaminated by oil.

This is more necessary with trucks that are above 100,000 miles or those that are utilized in towing and loading heavy trucks. Our Cummins truck stopped leaking after installation.

Duramax (L5P & LML)

L5P Issue: The factory plastic CCV units on the L5P engine may crack or deform with time. This causes small leakage of boost and results in the contamination of the intake by oil vapor.

Solutions:

• Internal catch cans: They are perfect in cold climate conditions, because they are placed close to the valve cover, where they become warm with engine heat.
• External catch cans: Greater separation and filtration of oil; however, more likely to freeze in winter.

Duramax owners should weigh climate, towing usage, and engine modifications when choosing a reroute solution.

Engine	Issue	Fix Recommendation
Powerstroke	Clogging box	Reroute with sensor trick
Cummins	Saturated filter	Billet breather
Duramax	Cracking unit	Internal catch can

Check your miles and symptoms. Reroutes fit most and save headaches.

Types of CCV Reroute Kits: Atmosphere vs. Catch Can

Cheap vents drip oil, while fancy cans need emptying. Pick wrong and face messes.

Types include atmosphere vent, catch can, and internal separation. Each has its pros for different needs.

When selecting a CCV reroute system, there are three main types:

Vent to Atmosphere (Draft Tube)

• Pros: Affordable, simple to install, effective at removing blow-by gases.
• Cons: Produces noticeable odor ("school bus smell") and can leave oil spots if not managed properly.

This is often preferred for DIYers or older trucks without emissions restrictions. It vents gases under the truck. Good for budget builds.

Catch Can System

Many owners prefer catch cans for diesel engines because they separate oil mist efficiently while keeping odors and environmental mess to a minimum.

• Pros: Keeps oil contained, reduces odor, and prevents driveway spots.
• Cons: More costly (in most cases, $300+). Traps oil in a can that you empty every oil change. Don't forget or it overflows.
• Catch can systems would suit well with the daily drivers and trucks, where the maintenance convenience and cleanliness are the primary factors.

Internal Separation

• Pros: It is a mix of the two worlds; it keeps the oil in the engine, but releases the pressure.
• Cons: High-performance and engine-specific, though perfect in cold climates and deleted or tuned trucks.

Internal separation kits are increasingly popular for modern 6.7 Powerstroke and Cummins setups.

CCV Reroute with EGR and DPF Deletes

Blow-by issues are often exacerbated after removing the EGR or DPF. These deletions increase exhaust flow and turbo activity, which in turn pushes more vapors through the CCV system.

CCV issues worsen after deletes because more gases and no burn-off. Rerouting complements by keeping oil out.

Why CCV Issues Worsen After Deletes

EGR and DPF burn some vapors, but deletes stop that. More oil enters the intake, mixing with soot. We saw manifolds clog in months on deleted trucks without reroutes.

How CCV Rerouting Complements EGR/DPF Removal

Reroute removes oil before it mixes. Cleaner air path means better flow and power. It prevents deposits that deletes expose.

Why a Reroute is Important with Deletes

• Reduces sludge formation in the intake and intercooler
• Protects turbo seals and boosts efficiency
• Improves long-term engine reliability

Recommended Order for Modifications

1. EGR/DPF delete
2. CCV reroute
3. Tuning

Order	Mod	Reason
1	EGR/DPF Delete	Base emissions removal
2	CCV Reroute	Handle extra blow-by
3	Tune	Optimize performance

Following this sequence ensures the engine remains clean and avoids unnecessary stress on the turbo and intake system. Our deleted Cummins runs smoothly with this setup.

Common Signs You Need a CCV Reroute

Oil in pipes means trouble, and ignoring it leads to breakdowns. Spot signs early.

Signs include oil in the charge pipes, boot failures, excessive oil use, and a dirty turbo inlet. Act fast.

Before installing a reroute, it's good to identify these common symptoms:

• Oil inside charge pipes: Often noticed when checking intercooler boots. Factory CCV lets it in. Reroute stops this.
• Repeated intercooler boot failures: Boots that have been slick or have worn away will be easily released. Common in towing.
• Overuse of oil: Burns or spills more oil than usual. It's burning in cylinders from CCV.
• Dirty turbo inlet: This is an observable accumulation of debris within the turbo compressor. We check this on every service.

When you observe any of such problems, a CCV reroute may curb the additional damage and enhance engine performance.

Sign	Cause	Fix
Oil in Pipes	Mist entry	Reroute
Boot Failures	Degraded rubber	Dry system
Oil Loss	Burning vapors	Separate oil
Dirty Inlet	Buildup	Vent externally

These signs show up around 100k miles. We fixed many trucks by spotting them.

CCV Reroute Installation Overview: What's Involved

The installation seems hard, but wrong steps cause leaks. Installing a CCV reroute isn't extremely complicated, but it requires attention to detail. Know what's needed.

Installation uses kit components, takes 1-2 hours, and suits DIY with tools.

Typical Kit Components in a CCV Reroute Kit

• Breather fittings to connect valve covers or crankcase outlets
• Hoses and clamps to route vapors safely
• Catch can or vent filter, depending on kit type

Installation Time

For most trucks, installation can take anywhere from 1–3 hours. More advanced DIYers will be able to do it on their own; less professional owners might want to have it installed professionally.

DIY vs Professional Install

• DIY: Viable in case you feel confident with your hood, and you possess fundamental hand tools.
• Professional: Use when you wish to have correct routing, freeze prevention, or when you are installing an engine-sensitive kit, which may need sensitive sensor compatibility.

Step	Time	Tools Needed
Remove Old	30 min	Wrench, pliers
Install New	45 min	Screwdriver
Test	15 min	Drive check

Follow guides. Our first install took longer, but now it's quick.

FAQs

Is a CCV Reroute Legal?

Off-road, yes, but street vents break emissions. Use cans for legal compliance.

Will a CCV reroute void my warranty?

Possibly impacts the warranty on the powertrain; therefore, inquire with your dealer. Remove for service.

Does a CCV reroute add horsepower?

Not directly, but a cleaner system boosts efficiency by 5-10 hp. It preserves turbo efficiency and airflow.

Is a CCV reroute better than a catch can?

Reroute includes a catch can often. Depends on climate, engine type, and maintenance preferences. Both vent, but the reroute is full mod.

Why does my truck smoke after a CCV reroute?

The little leakage of vapour at idle is natural; it is simply blow-by gases.

How often should I empty my catch can?

Typically, every oil change or or 5,000 miles, as recommended by the kit manufacturer.

Is tuning required?

Only for specific platforms, like the 6.7 Powerstroke with sensor-based ECMs. Others no.

Will it stop oil in the intercooler boots?

Yes, when installed correctly.

Can it cause crankcase pressure issues?

Only if hoses freeze, are too small, or are improperly routed. If blocked, yes. Use large hoses.

Should I install one on a stock engine?

Yes, it is always best to avoid repairing over 50k miles, than maintaining things in good condition.

Final Verdict: Is a CCV Reroute Worth It?

So, what does a CCV reroute do? By eliminating the oil-contaminated blow-by gases in the intake system, a CCV reroute will keep the diesel engine clean and dependable.

Who Should Install One

• Diesel owners who want long-term engine protection
• Trucks used for towing or heavy-duty work
• Engines that have deletes or performance tuning

Best Use Cases

• Stock engines aiming for preventative reliability
• Tuned or deleted engines to prevent turbo and intake contamination
• Cold-weather applications using internal or external catch can setups

A CCV reroute is one of the most cost-effective and reliable diesel upgrades you can make. It maintains the dryness of your turbo, stops intake sludge, minimizes boost leakage, and keeps your intercooler and piping clean for years.

Although your truck might be stock, a properly-fitted CCV-reroute will still ensure that you do not fall prey to the inconveniences that might turn into big headaches. We recommend EGR Performance as the best choice for performance upgrade to fix these issues.

More Reading

• What's a CCV Filter
• CCV Filter Change Intervals
• What Does The CCV Filter Do On A 6.7 Cummins