4" Marine Bilge Blower - Engine Compartment Ventilation 5-3715

Why a Bilge Blower is Important

Gasoline vapors can collect in enclosed areas of a boat, particularly around an inboard or sterndrive engine compartment. Because gasoline vapor is highly flammable, proper ventilation is an important part of the boat's fuel and engine safety system.

A powered bilge blower helps remove air and vapors from the lower areas of the compartment and exhaust them outside the boat.

The blower should be treated as a safety component, not simply as a fan for cooling the engine compartment.

Matching 4" Blower Hose

4" Heavy-Duty Vinyl Blower Hose - 420-4

Matching 4" ventilation hose for routing intake and exhaust airflow through compatible marine bilge blower systems.

Keep the hose run as smooth and direct as practical. Crushed sections, sharp bends and excessive hose length can restrict airflow.

View 4" Blower Hose

Matching 4" Blower Hose Clamp

German-Style Hose Clamp - 4-17

Matching clamp for securing the 4" blower hose to compatible blower outlets and ventilation fittings.

Properly securing the ducting helps prevent the hose from working loose due to vibration, movement or servicing inside the engine compartment.

View 4-17 Hose Clamp

3" and 4" Bilge Blower System Guide

Need a 3" Bilge Blower Instead?

3" Bilge Blower - 5-3710

Smaller blower option for marine ventilation systems designed around 3" ducting.

View 3" Bilge Blower

3" Heavy-Duty Vinyl Blower Hose - 420-3

Matching 3" marine ventilation hose for compatible 3" blower systems.

View 3" Blower Hose

German-Style Hose Clamp - 4-13

Matching clamp for compatible 3" blower-hose installations.

View 4-13 Hose Clamp

How a Marine Bilge Blower System Works

A powered ventilation system uses the blower and ducting together to move air through an enclosed engine compartment.

The blower provides the airflow while the hose directs the air from the intended area of the compartment toward an exterior vent.

For the system to work properly, the blower, hose, clamps and vents must all remain connected and unobstructed.

Why Blower Size Matters

A 4" blower system is designed around 4" ducting. Using smaller hose or reducing the duct diameter can create additional airflow restriction.

When replacing a blower, match the new unit to the boat's existing ventilation design and original hose size unless the boat manufacturer specifies another configuration.

Bilge Blower Installation Tips

• Match blower diameter to the ventilation hose and vent fittings.
• Use the correct hose clamps to secure duct connections.
• Keep blower hose runs as short and direct as practical.
• Avoid crushed ducting, sharp bends and severe kinks.
• Support flexible hose so it cannot fall into accumulated bilge water.
• Keep intake and exhaust openings free of stored gear and debris.
• Verify airflow direction during installation.
• Inspect wiring and electrical connections when replacing the blower.
• Test blower operation before starting the gasoline engine.

When Should a Bilge Blower Be Replaced?

A blower should be inspected if ventilation airflow becomes weak, the unit becomes unusually noisy or it no longer operates reliably.

Common reasons to replace or inspect a blower include:

• Blower does not turn on
• Intermittent operation
• Reduced airflow
• Unusual bearing or fan noise
• Damaged blower housing
• Corroded or damaged wiring connections
• Old or damaged ventilation hose

Marine Wiring Supplies

When replacing a bilge blower, inspect the wiring and connections at the same time. Pro Marine stocks common wiring supplies for marine electrical repair and installation.

Blue Butt Connectors - BBC - 25 Pack

Electrical butt connectors for compatible marine blower and wiring repairs.

View Blue Butt Connectors

1/4" Red Heat Shrink - 14R

Red heat-shrink tubing for protecting compatible electrical connections and identifying positive wiring.

View Red Heat Shrink

1/4" Black Heat Shrink - 14B

Black heat-shrink tubing for protecting compatible electrical connections in marine installations.

View Black Heat Shrink

Key Features and Benefits

• 4" marine bilge blower
• Designed for compatible powered marine ventilation systems
• Helps exhaust gasoline vapors from enclosed engine compartments
• Matching 4" heavy-duty vinyl blower hose available
• Matching German-style 4-17 clamp available
• Complete 3" blower system also available
• Marine butt connectors and heat shrink available
• Useful replacement component for inboard and sterndrive ventilation systems

FAQ

What size is item 5-3715?
Item 5-3715 is a 4" marine bilge blower.

What hose goes with this blower?
Use the 420-4 4" Heavy-Duty Vinyl Blower Hose in compatible 4" ventilation systems.

Which clamp fits the 4" blower hose?
Use the German-Style 4-17 Hose Clamp .

What does a bilge blower do?
A bilge blower moves air through a compatible enclosed engine compartment to help exhaust gasoline vapors and ventilate the space before engine startup.

Should I run the blower before starting a gasoline inboard or sterndrive?
Yes. Follow the boat manufacturer's operating instructions and inspect the engine compartment for gasoline vapor before starting the engine.

Can I replace a 4" blower with a 3" blower?
Do not automatically reduce the ventilation system size. Match the replacement blower to the boat's original airflow and ducting requirements.

Do you carry a 3" bilge blower system?
Yes. Pro Marine stocks the 5-3710 3" Bilge Blower , 420-3 3" Blower Hose and matching 4-13 clamp.

Do you carry wiring supplies for the blower?
Yes. Pro Marine stocks blue butt connectors, red heat shrink and black heat shrink.

Searchable Terms

5-3715, 4 inch bilge blower, 4 inch marine blower, boat bilge blower, marine ventilation blower, engine compartment blower, gasoline engine ventilation, bilge ventilation fan, marine exhaust blower, 420-4, 4 inch blower hose, 4-17 hose clamp, German style hose clamp, 5-3710, 3 inch bilge blower, boat ventilation fan