Install an Oil Catch Can: PCV Setup and Routing Walkthrough

Introduction

Blow-by pushes oil vapor straight into your intake. Over time, that vapor turns into sludge and carbon buildup. A properly installed catch can stops the damage before it starts and keep a clean intake.

Install a baffled catch can or oil separator in the closed PCV loop by routing dirty crankcase vapors to the IN port, cleaned air to the intake or turbo inlet pipe, using oil-rated hose, sealed fittings, and correct elevation so gravity and vacuum keep the system flowing without leaks or backpressure.

This guide will walk through tools, mounting, and hose routing to ensure a clean, reliable installation, rather than one that causes codes or oil starvation. Follow the instructions to learn how to install oil catch can setups, including the layout rules, the step-by-step sequence, and the turbo-specific checks, and you will have a leak-free PCV system.

Quick Answer: How to Install an Oil Catch Can

The oil catch can is a simple component that can be installed in a few minutes.

• Choose a safe location that is not near any heat sources.
• Install the PCV valve hose on the "IN" port of the can.
• Connect another hose from "OUT" to the intake.
• Use thread seal tape to seal all fittings.
• Turn on the engine and inspect for leaks.

That's the quick, easy version of how to install oil catch can systems. The rest of this guide covers every step in detail.

What Does an Oil Catch Can Do in the PCV System?

An oil catch can sits in the closed PCV loop, traps oil vapor and condensation from crankcase gases, and returns cleaned air to the intake so carbon and sludge never form on valves or in the manifold.

How the PCV Loop Moves Blow-By

Combustion pressure forces a small volume of gases past the piston rings. These gases carry oil vapor, fuel residues, and water. The PCV valve or valve-cover breather routes them out of the crankcase.

In a stock system the mixture travels straight into the intake tract. On port-injected engines the oil mostly hits the back of the intake valves and burns off.

On direct-injection engines the valves stay dry, so the oil sticks and hardens into carbon. Boosted engines raise crankcase pressure and increase the volume of blow-by, accelerating the same process.

How an Oil Catch Can Works in the PCV System

The PCV system of your engine releases crankcase gases into the intake. Those gases are accompanied by fine oil mist. The mist is caught in a catch can before it enters the intake. This keeps carbon deposits off your intake valves.

A catch can prevents sticky carbon deposits from baking onto intake valves and intercooler piping. To learn how trapping these crankcase vapors improves combustion efficiency and valve longevity, review our complete guide on oil catch can benefits.

Why Drivers Add a Catch Can

Blow-by is the worst problem in boosted, supercharged, and direct-injection engines. These engines are the ones that will benefit most from a catch can install. Even naturally aspirated engines get a little bit of protection as well.

When the Benefit Is Highest

Turbocharged and supercharged engines produce the highest blow-by volumes under boost. Direct-injection engines suffer the most from valve deposits.

High-mileage or track-driven engines with increased ring gap also benefit. Naturally aspirated daily drivers still gain from cleaner intake tracts, but the return is smaller.

How Oil Separators Differ from Basic Catch Cans

Not all catch cans are created equal. A basic catch can is a sealed reservoir with internal baffles or mesh. Oil and water drop out and collect until you drain them.

An active oil separator (AOS) adds coalescing media or a centrifugal stage and usually includes a gravity drain line that returns the collected oil to the oil pan. The separator therefore needs less frequent service and can handle higher flow rates without becoming restricted.

Catch Can and Oil Separator Types

What Tools and Parts Do You Need Before Starting?

You need a baffled catch can or AOS, oil-rated reinforced hose, high-torque clamps, thread sealant, a vehicle-specific or universal bracket, and basic hand tools; for AOS units add a drain-back fitting and check valves if the engine is boosted.

Collect all the items before you begin. This eliminates mid-job trips to the parts store.

• Sockets, wrenches, and screwdrivers
• Hose cutter and spring clamp pliers
• Thread seal tape or liquid sealant
• Oil-rated reinforced hoses and clamps
• Universal or vehicle-specific mounting bracket

Selecting a canister with an internal baffled filtration mesh ensures optimal oil-air separation even under high manifold vacuum or heavy boost conditions.

Explore our high-flow Crankcase Filter Collection to source universal and vehicle-specific canisters, mounting brackets, and drain valves.

The first step in properly fitting an oil catch tank is having the correct parts list. Leaks occur later if the hose or clamps are wrong for the job. It's better to pay a bit more now than to deal with the hassle later.

Where Should You Mount the Oil Catch Can?

Mount the catch can high on a strut tower, radiator support, or firewall point so it stays vertical, accessible for draining, and clear of exhaust heat; active separators must sit higher than their drain-back port so gravity returns oil without backup.

The location is as important as the parts you select. Picking where to install oil catch can hardware affects long-term reliability.

• Select a location that is high in the engine compartment.
• Avoid placing it near the exhaust manifold and turbo.
• Allow for easy access to the drain later.
• Do not use tight bends when routing hoses to the spot.

Oil should flow, not be pushed or pulled out of the way. A bad location equals more maintenance problems down the road.

How Do You Install an Oil Catch Can Step by Step?

Identify the factory PCV hose, disconnect it, mount the can, run oil-rated lines from the dirty source to the IN port and from the OUT port back to the intake or TIP, clamp every joint, then start the engine and confirm zero leaks and stable idle.

Follow these steps in order for a clean, reliable result.

Here are the quick steps:

1. Find the factory PCV hose that leads to the intake.
2. Remove the stock hose and check the fittings.
3. Apply thread sealant to the catch can's ports.
4. Bolt the mounting bracket to your chosen location.
5. Trim oil-rated hose to length for both ports.
6. Attach the IN port to the PCV valve line.
7. Reconnect the OUT port to the intake.
8. Make sure all clamps are tight to avoid vacuum leaks.
9. Verify hoses are not kinked, collapsing, or rubbing.
10. Run the engine and check for leaks or rough idling.

The Detailed Installation Guide

Step 1. Identify Factory Lines

Locate the hose that leaves the PCV valve or the valve-cover breather and runs toward the intake. Note whether it uses a quick-connect fitting or a spring clamp.

Step 2. Remove the Original Hose

Release the OEM fittings and remove the stock line. Inspect the plastic or metal nipples for cracks or residual oil sludge.

Step 3. Prepare Fittings and Bracket

Apply thread sealant or Teflon tape to every catch-can fitting. Bolt the mounting bracket so the can will sit vertical. On AOS units install the drain-back hose first and confirm a continuous downward slope with no dips.

Step 4. Mount the Can

Secure the bracket to a chassis bolt or designated mounting point. Double-check that the can cannot contact moving parts or hot surfaces when the engine rocks under load.

Step 5. Dry-Fit and Cut Hoses

Measure the path from the PCV source to the IN port and from the OUT port back to the intake. Cut the oil-rated hose to length so the runs form smooth arcs without tight bends or low spots.

Step 6. Connect the Dirty Line

Push the hose onto the IN port and secure it with a high-torque clamp. Route the line so it cannot chafe or collapse.

Step 7. Connect the Clean Line

Run the second hose from the OUT port to the intake manifold or turbo inlet pipe. On dual-port separators also connect any vacuum-reference lines to the correct ports.

Step 8. Clamp Everything

Tighten every clamp. A loose clamp is the most common source of vacuum leaks after installation.

Step 9. Final Routing Check

Verify that no hose is kinked, rubbing on sharp edges, or near belts or exhaust. Adjust as needed.

Step 10. Start and Leak-Check

Reconnect the battery. Start the engine and listen for idle quality. Spray a light mist of soapy water or use a smoke tester on every joint. Any bubbles or idle change means a leak that must be fixed before road testing.

This is the basic procedure for installing a oil catch can on most engines. Knowing how to hook up a catch can the right way prevents costly rework.

Plumbing the Hoses: IN Port vs. OUT Port

People don't realize how important hose direction is. Reversed ports send oil directly into the intake.

The "dirty" side connects to the PCV valve or breather. This hose connects to the "IN" port on the can. The "clean" side runs from "OUT" to the intake manifold or turbo inlet pipe.

Getting oil catch tank installation wrong here defeats the whole purpose. Double-check your routing before starting the engine. Knowing how to hook up a catch can the right way safeguards your intake in the long run.

How Should You Route Hoses on Turbo and Supercharged Engines?

On boosted engines use a check valve so boost cannot enter the catch can, route the clean side to the turbo inlet pipe where pre-turbo vacuum still exists, and never reverse the IN and OUT ports or the baffles become useless.

There are a couple of additional factors to consider with boosted engines. Positive manifold pressure affects how the PCV system behaves.

• Fit a check valve to prevent boost pressure from flowing back into the can.
• Connect the clean line to the turbo inlet pipe, NOT the manifold.
• Use dual catch cans to separate the PCV and breather sides.

Diesel trucks also come with their own set of complexities. How to install an oil catch can on diesel engine setups depends on the PCV layout. More crankcase volume is typically routed on diesel platforms than on gas engines.

For forced-induction and heavy-duty diesel engines where elevated crankcase pressure demands high-diameter hose routing, a complete bypass or open-atmosphere line setup may be required.

Browse our heavy-duty CCV PCV Reroute Kits for custom-engineered hose fittings, delete plugs, and routing hardware. Learn how a CCV reoute works for diesel engine.

When installing a oil catch can on any boosted platform, extra care must be taken with check valves.

What Are the Most Common Installation Mistakes?

Avoid soft vacuum hose that collapses, reversed ports that bypass the baffles, low hose dips that trap fluid, hard-to-reach mounts that discourage draining, open VTA conversions that build crankcase pressure, and AOS units mounted below the oil-pan return port.

The majority of failures are due to a few recurring errors.

• Using inexpensive, soft hose that collapses under vacuum.
• Reversing the IN and OUT ports by accident.
• Creating hose dips where oil and water collect.
• Installing in places you can't reach to service.
• Skipping the check valve on turbo applications.

All of these mistakes disappear once you learn how to install oil catch can systems the right way. A hurried oil catch tank installation is virtually guaranteed to result in a comeback repair.

How Do You Verify the Installation Is Working?

After installation the idle should be stable, every fitting dry, the intake tract free of oil, and no CEL present; rough idle, hissing, or codes P0171/P0174 indicate a vacuum leak or collapsed hose that must be corrected.

Signs of a Correct Install

Idle speed remains steady. No oil weeps from fittings. The intake pipe and intercooler stay clean. Throttle response feels unchanged or slightly sharper because the charge air is freer of oil.

Symptoms of Problems

Rough or surging idle points to a vacuum leak. Whistling or hissing noises confirm the same. Lean or rich codes appear when unmetered air enters. A burning-oil smell in the cabin can mean the can is overfilled or a hose has come loose under boost.

How Often Should You Drain and Maintain the Catch Can?

Check and drain the catch can every 3,000 miles or at every oil change; cold weather, short trips, high boost, and engine wear all increase the volume of fluid collected and may require shorter intervals.

Drain Interval Factors

Cold ambient temperatures and short trips produce a milky water-oil emulsion that fills the can faster. High-boost and track sessions increase blow-by volume.

High-mileage engines with larger ring gaps also generate more fluid. In these conditions inspect the can every 1,000–1,500 miles until you know the rate for your vehicle.

Safe Draining and Cleaning

Treat the collected fluid as hazardous waste oil and dispose of it at an approved facility. Once a year remove the can, rinse the stainless baffles with solvent or brake cleaner, and let everything dry before reassembly. Never use compressed air that could damage fine mesh media.

Quick Installation Checklist

Knowing how to install oil catch can basics keeps costs predictable. Go through this before you say you're finished.

• Mounting bracket is secure and level.
• All fittings are thread-taped.
• Hoses are oil-rated and free of kinks.
• IN port is connected to the PCV/crankcase side.
• OUT port is connected to the intake or TIP.
• Check valve installed on boosted engines.
• No leaks were found when the engine was started.

Frequently Asked Questions About Oil Catch Can Installation

Where to install oil catch can hardware for the best results?

Mount an oil catch can high in the engine bay, away from extreme heat sources like turbochargers or exhaust manifolds, and inline between the PCV valve and the intake manifold.

Do I need a tune after installing a catch can?

No. A properly installed catch can doesn't require any tuning. It only filters vapor before it gets into the intake.

Will a catch can cause a check engine light?

A properly installed catch can does not cause a check engine light, but a light can occur due to vacuum leaks from loose hoses, damaged integrated sensors on factory PCV lines, or a clogged filter causing crankcase pressure issues.

Is a catch can worth it on a direct-injection engine?

Yes, an oil catch can is generally worth it on a direct-injection (GDI) engine. Because fuel is injected straight into the cylinder rather than through the intake runners, gasoline never washes over the intake valves.

What happens if I install the ports backward?

Installing port fittings backward in an oil catch can or crankcase ventilation system forces oil mist straight through the outlet instead of filtering it.

This reverses the intended airflow direction, defeats the separation process, lets raw oil enter the intake tract, and causes heavy carbon buildup or engine smoke.

Do I need a check valve on a turbo engine?

Yes, a turbo engine needs check valves, but not directly in the main turbo assembly itself.

How often should I drain the catch can?

Every 1,000 to 3,000 miles (1,500 to 5,000 km), or match it with every regular engine oil change. New setups should be checked weekly or after the first 500 miles to learn how fast your specific engine builds up blow-by fluid.

Which hose connects to the IN port on an oil catch can?

The dirty line that leaves the PCV valve or valve-cover breather always connects to the IN port so vapor must pass through the baffles or coalescing media before reaching the intake.

Does the OUT port go to the intake manifold or the turbo inlet pipe?

On naturally aspirated engines the OUT port returns to the intake manifold. On turbo engines it usually returns to the turbo inlet pipe (TIP), where vacuum still exists upstream of the compressor even under boost.

Is a dual catch can setup better than a single catch can?

Dual cans isolate both the PCV and fresh-air breather sides and give the highest protection on high-blow-by engines, but a single well-baffled can is sufficient for most street use.

What is the difference between an oil catch can and an oil separator?

A catch can collects oil for manual draining. An oil separator uses finer media and usually returns the oil automatically to the oil pan, reducing maintenance.

Will installing a catch can affect engine performance or fuel economy?

The change is usually too small to measure on a street car. The real gain is long-term cleanliness and reduced carbon on the intake valves.

Is a cheap universal catch can worth it?

A basic empty can offers little separation. Spend the extra money on a baffled unit; the difference in filtration is large.

Final Thoughts: Get Your Catch Can Install Right

If you do it correctly, you'll keep your engine safe for years. Every step here matters more than any single part choice.

• Mount high, away from heat sources.
• Route IN to the PCV side, OUT to intake.
• Seal all fittings with oil-rated hose and test for leaks.

Correct oil catch can installation keeps your intake clean and protects valves, intercoolers, and long-term engine health. For the most durable baffled cans and AOS units built for heavy-duty platforms, choose EGR Performance.

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.

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