Install L5P CCV Reroute for 2017–2025 Duramax: Expert Guide

Introduction

The stock plastic CCV housing on your 2017–2025 6.6L Duramax L5P tends to fail over time. Once it cracks or clogs, oil mist ends up inside the turbo and intercooler piping. That mess reduces airflow and can shorten the life of expensive components.

An L5P CCV reroute kit replaces the failure-prone plastic housing with a billet aluminum block that cleanly diverts oily vapors, prevents intake contamination, and, on the EGR Performance design-specific version, improves engine-bay access.

Most installers finish the job in 30 to 60 minutes. First-timers or trucks with stubborn factory bolts may need a bit longer.

Below, we cover every step from pre-check (fitment notes, safety steps) to post-install test drive so you finish the job right the first time and keep your L5P running strong. What's more, there is also a troubleshooting section for common issues after installation.

L5P CCV Reroute Kits Fitment: Compatible Trucks & Pre-Check

L5P CCV reroute kits fit 2017-2025 Chevy Silverado HD 2500/3500 and GMC Sierra HD 2500/3500 with the 6.6L Duramax. 2017-2019 models use the standard CCV design. 2020-2023 models require charge-pipe clearance confirmation. 2024-2025 models need manufacturer-specific verification because Cab & Chassis versions may have different packaging.

Pre-order checklist

• Before ordering, check your model year twice. Compare it against the kit manufacturer's current fitment list, or pull your VIN and send it to customer service.
• Then measure the distance between the factory valve cover pad and the intercooler charge pipe to confirm clearance.
• Also check local emissions rules since some kits carry off-road use disclaimers.
• Many kits include a boost block-off plate specifically for L5P trucks, so verify that the part matches your setup.

While all 2017–2025 6.6L diesel platforms utilize a closed crankcase design, minor factory plumbing updates were introduced across model years. Before ordering hardware or removing factory fittings, verify your engine generation specs, stock power ratings, and turbocharger inlet configurations in our l5p duramax specs reference.

Tools and Parts Needed for L5P CCV Reroute Kits Installation

Metric socket set, ratchet, extension bars, 5 mm Allen bit, long-nose pliers, flathead screwdriver, bolt extractor set, clean rags, and flashlight form the basic toolkit. The EGR Performance kit adds a billet aluminum PCV/CCV block, high-temp O-rings, anodized mounting hardware, reinforced silicone reroute hose, barbed or AN fittings, hose clamps, zip ties, and an intake port boost block-off plate.

Having the right tools ready before you start saves time and avoids mid-job frustration.

Tools Required

• Metric socket set and ratchet
• Extension bars for tight clearance
• 5mm Allen or hex bit if the kit calls for it
• Long-nose pliers
• Flathead screwdriver or a trim pry tool
• Bolt extractor or easy-out set for stuck factory bolts
• Clean shop rags
• Flashlight or work light

Included Kit Components

Most kits ship with a billet aluminum CCV block, high-temp O-rings or a mounting gasket and anodized hardware. You also get a reinforced silicone hose with barbed or AN fittings, hose clamps, a block-off plate, and zip ties for routing.

Recommended Prep and Safety Gear

Wear gloves and eye protection while working under the hood. Keep a torque wrench on hand set to factory spec in inch-pounds or foot-pounds. O-ring lube or clean engine oil helps seat new seals properly.

Before CCV Reroute L5P Installation: Safety and Engine Bay Prep

Disconnect both negative battery terminals to prevent shorts around tight metal. Allow the engine to cool completely so hot turbo, charge pipe, and exhaust manifolds do not cause burns. Move or detach the intercooler boost pipe for access, then cover all open ports with clean shop rags to stop dirt or bolts from falling inside.

A few prep steps of CCV Reroute L5P installation protect both you and the engine before any bolts come off.

Disconnect Both Batteries

Pull the negative terminals first. This prevents shorts while you work near tight metal components.

Allow the Engine to Cool

Hot turbo housings, charge piping, and exhaust manifolds can cause burns. Give the engine time to cool fully.

Clear Access Space

Move the intercooler boost pipe out of the way if it blocks the rear valve cover area.

Cover Open Ports

Place clean rags over any open intake or intercooler piping right away. This stops dirt or loose bolts from falling inside.

Step-by-Step L5P CCV Reroute Installation

Installing a billet crankcase ventilation (CCV) reroute kit on an L5P Duramax requires carefully moving the intercooler charge pipe, removing the degraded factory plastic housing and mounting hardware, cleaning the valve cover mating surface, installing the intake block-off plate, assembling and bolting down the new billet block, routing the discharge hose safely, and performing a final inspection of all fasteners and connections upon reassembly.

Once prep is done, the actual install follows a clear order. Each step builds on the last so skipping ahead usually causes problems later.

Step 1: Remove or Move the Intercooler Charge Pipe

Loosen the clamps near the rear intake area. Slide or pivot the pipe aside to open up working room near the turbo.

Step 2: Locate and Disconnect the Factory CCV Housing

Find the black plastic CCV assembly at the top rear of the engine. Unclamp the factory vapor hoses using pliers or a trim tool.

Step 3: Remove the Factory Mounting Bolts

Take out all four retaining bolts. Some trucks use one-way safety bolts, so keep an extractor socket handy if the heads look unusual.

Step 4: Lift Out the Stock CCV Assembly

Lift the old plastic housing free of the engine bay. Wipe the mating surface clean so no grit enters the valve cover.

Step 5: Install the Boost Block-Off Plate

Fit the supplied block-off plate or plug into the factory intake inlet port. This seals the tract and stops boost leaks or unmetered air.

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Step 6: Assemble the New Billet Block

Thread the barbed or AN fitting into the new CCV block. Lube the O-rings lightly with clean oil and seat them in their grooves. Keep everything hand-tight for now.

Step 7: Mount the New CCV Block

Set the billet block over the valve cover pad. Thread the bolts in by hand first to avoid cross-threading then torque them evenly to spec.

Step 8: Attach and Route the New Hose

Push the reroute hose onto the outlet fitting and clamp it down. Route it carefully following the safety guidance below.

Step 9: Reinstall the Boost Piping

Put the intercooler pipe back in its factory spot. Tighten every clamp and check clearance around the new billet block.

Step 10: Final Fastener and Electrical Check

Reconnect the negative battery terminals. Recheck clamp tightness the block-off plate and hose supports before closing the hood.

How to Route the PCV Hose on L5P Safely

How you route your PCV reroute L5P hose matters as much as proper installation. Poor routing creates problems that appear as leaks or performance issues later.

Keep the hose at least 12 inches from exhaust manifolds, downpipes, and the turbo. Clear the serpentine belt, steering shaft, and suspension. Avoid kinks or low loops where oil mist can condense. Angle the outlet downward behind the front axle and secure every 12-18 inches with zip ties or cushioned P-clamps.

Maintain Heat Distance

Keep the hose well away from exhaust manifolds, downpipes, and the turbo housing.

Avoid Moving Parts

Route clear of the steering shaft, serpentine belt drive pulleys, and suspension parts.

Prevent Kinks and Low Spots

Skip tight 90-degree bends that restrict airflow. Avoid low loops where oil mist can pool and block the line.

Position the Discharge Safely

Angle the hose end downward toward the ground behind the front axle. Never point it toward the cab vent, brakes, tires, or steering linkage.

Secure Support Points

Fasten the hose with zip ties or cushioned clamps every 12 to 18 inches along the frame rail.

Securing the silicone bypass hose with smooth chassis runs is critical; any kink or heat damage from exhaust piping creates crankcase over-pressurization and main seal leaks.

For a complete structural understanding of your engine bay layout and maintenance procedures, consult our 15p duramax guide.

Post-Installation Inspection and Test Drive

Start the engine and idle for 5 minutes while listening for whistling or unusual noises at the block-off plate and valve cover. Visually inspect for oil seepage at seals and connections. Take a 5-10 minute test drive and watch for check engine lights or oil smells in the cab. After the drive, cool the truck and re-torque all bolts and clamps.

Testing the install properly catches small issues before they turn into bigger ones.

Initial Startup Check

Start the engine and let it idle. Listen near the block-off plate and valve cover base for whistling or odd noise.

Visual Inspection

Look for oil seeping from the seal base O-rings or hose connections while the engine runs.

Short Test Drive

Drive for 5 to 10 minutes. Watch for check engine lights or oil smell inside the cab.

Post-Drive Inspection

Let the truck cool, then recheck every bolt, clamp and zip tie once the parts have gone through a heat cycle.

Common L5P CCV Reroute Problems and Troubleshooting

Troubleshooting an L5P CCV reroute installation involves addressing common issues such as stripped factory bolts using extractor sockets, eliminating cabin oil odors by extending hoses away from HVAC inlets, stopping base plate oil seepage through proper surface cleaning and O-ring alignment, preventing hose collapse with high-temperature reinforced silicone, and diagnosing internal engine wear if excessive crankcase blow-by persists.

Even careful installers sometimes encounter issues during setup. Knowing how to handle problems keeps your L5P CCV reroute or delete project on track.

Factory Bolt Heads Strip or Spin

This usually happens with factory safety bolts. Use a bolt extractor socket or apply steady pressure with vice-grips to remove it.

Strong Oil Smell Inside the Cab

The hose outlet likely sits too close to the HVAC intake. Extend or reroute the hose farther along the frame rail.

Oil Seepage at the Billet Base Plate

This points to a misaligned O-ring dirty mating surface, or uneven torque. Clean the surface, check the O-ring, and re-torque evenly.

Kinked or Collapsed Hose

Usually caused by a tight bend or a hose that has softened from heat. Use a wider bend radius and replace the hose with a high-temperature reinforced option.

Excessive Oil Vapor or Heavy Dripping

This can signal high crankcase pressure or internal blow-by. A reroute kit manages vapor but cannot fix worn rings or internal wear.

Troubleshooting Table

Additional Troubleshooting Notes

A stripped bolt is usually the security-type fastener used on 2020+ trucks, and extractors save time and prevent damage to the valve cover.

Oil odor in the cab is almost always the hose end, and a quick reroute move fixes it in five minutes. When vapor is excessive, the reroute is working correctly; the real fix is addressing crankcase pressure from worn rings or turbo seals.

Maintenance Tips After L5P CCV Upgrade

Inspect clamps after the first 100 miles and again at every oil change. Check the silicone hose for abrasion, heat cracking, or soft spots every 10,000 miles. If your kit includes an inline catch can or breather filter, drain and clean the element every 5,000 miles to keep backpressure low.

Routine Maintenance Schedule

• A little upkeep keeps the new setup running clean for the long haul.
• Recheck clamp tightness after the first 100 miles and during oil changes
• Inspect the hose regularly for cracking abrasion or soft spots
• Clean or drain any catch can or breather filter every 5000 miles

Eliminating oil vapor contamination from your intake system preserves air purity and maintains intercooler heat transfer efficiency. Once your engine breather setup is optimized, discover complementary bolt-ons, high-flow intake horns, and durability modifications in our round-up of the best l5p upgrades.

FAQ

Is an L5P CCV reroute legal for street use?

Rules vary by state and region so check local emissions laws before installing one for street use.

Does an L5P CCV reroute kit require tuning?

A CCV reroute is purely mechanical, so it does not affect emissions compliance and requires no tune, though some owners pair one with other modifications that do.

Does an L5P CCV reroute add horsepower?

The main benefit is a cleaner intake tract rather than a direct power gain.

Is a CCV reroute the same as an EGR delete?

No, these are separate modifications that target different systems on the engine.

Will an L5P CCV reroute stop all oil in the intake?

It greatly reduces oil mist buildup but cannot eliminate every trace of it.

How long does L5P CCV reroute installation take?

Most installs take 30 to 60 minutes depending on bolt condition and experience level.

Why do owners replace the factory L5P CCV housing?

The factory plastic housing is prone to cracking and clogging over time.

Why does my truck smell like oil after a CCV reroute?

This usually means the hose outlet needs to be repositioned farther from the cab intake.

Will an L5P CCV reroute kit fit all 2017-2025 Duramax trucks?

Most kits fit this range. Note that 2024-2025 Cab & Chassis models may have packaging differences; always check the manufacturer's fitment list for your model year.

Can I install an EGR Performance L5P CCV reroute kit at home?

Yes most owners complete this as a home driveway install with basic hand tools.

Conclusion

Installing an L5P CCV reroute on a 2017-2025 6.6L Duramax is a manageable DIY project. It solves the shortcomings of the factory plastic CCV housing in a lasting way.

Rerouting the crankcase ventilation system stops oil vapor mist from coating your turbocharger compressor wheel, intake piping, and intercooler core. It keeps the intake path clean. It also helps prevent boost leaks and makes oil fills easier to reach.

To understand how oily blow-by sludge contributes to MAP sensor fouling and premature component failure, check out our diagnostic breakdown of common duramax l5p problems.

Confirm your truck's fitment first and keep a bolt extractor on hand for stubborn hardware. Route the hose carefully away from heat and moving parts.

Long-term, your L5P PCV reroute protects your turbo and intercooler from progressive contamination. You've invested in your truck's longevity through this modification.

Research quality kit options from trusted manufacturers like EGR Performance. Your Duramax will thank you with cleaner boost piping and longer turbo life.

About the Author - Mark Peterson

With 20 years under the hood of heavy-duty diesel trucks, I've seen every wrench turn and sensor failure imaginable. My mission is to help Powerstroke, Cummins, and Duramax owners push their engines to the limit. I don't just review parts - I provide field-tested solutions based on two decades of diagnostic data.

More Reading

• First Upgrades for Your L5P Duramax
• Everything You Need To Know: L5P Duramax
• Maintenance Tips for GMC Duramax Diesel Owners