9903002 | Genuine International® Viscous Air Sensing Fan Clutch

1. Reduce Oil in the Intake System

In a factory closed crankcase ventilation (CCV) system:

• Blow-by gases (oil vapor + combustion gases) go back into the intake.

• That oil mist can coat the turbo, intercooler, intake piping, and EGR components.

An open breather helps:

• Keep intake air cleaner

• Reduce oil buildup in the turbo and intercooler

• Lower carbon sludge formation

2. Help With Performance Builds

On modified or high-boost engines:

• Increased blow-by can overwhelm the stock CCV system.

• An open breather can relieve crankcase pressure more easily.

This can:

• Reduce crankcase pressure

• Help prevent oil leaks under boost

3. Simpler System (Fewer Components)

Some owners prefer:

• Fewer hoses

• No oil separator maintenance

• Less contamination of intake parts

4. Common in Off-Road or Race Applications

In racing or off-road builds where emissions compliance isn’t required, it’s often used to:

• Improve reliability

• Simplify engine bay setup

1. Strong Oil Smell

If you notice:

• Burning oil smell

• Fumes inside the cab (especially at idle)

The breather may be venting too close to the firewall, exhaust, or HVAC intake.

2. Oil Drips Under the Vehicle

You may see:

• Oil spots under the truck

• Wet residue around the breather hose

• Oil mist coating nearby components

This can happen if:

• There’s excessive blow-by

• The hose is too short

• No catch can or filter is installed

3. Excessive Crankcase Pressure

If the breather is clogged, kinked, or undersized, pressure can build up.

Signs include:

• Oil leaks from valve covers or seals

• Dipstick popping up

• Whistling noise from engine

4. Check Engine Light

Some modern vehicles monitor crankcase ventilation flow. An open breather conversion can cause:

• PCV/CCV system codes

• Emissions system warnings

5. Dirty Engine Bay

If the breather filter is low quality or missing:

• Oil mist may coat engine components

• Dirt may accumulate in oily areas

6. Whistling or Hissing Sounds

Improper routing or loose fittings can cause:

• Air leaks

• Vacuum issues (on gas engines especially)