Boat engine water filters are essential components for ensuring proper engine operation and longevity, especially in water-cooled inboard and outboard engines. There are different types of filters, each with a specific function:

Main types of water filters for marine engines

Water/fuel separator filter (racor):

• It does not filter sea water, but any water that may be present in the fuel (diesel or petrol).
• Essential to avoid engine damage due to fuel contamination.

Raw water strainer:

• Filters seawater before it enters the engine cooling system.
• Retains algae, sand, shells, plastic or debris that could clog the pump or lines.
• It must be inspected and cleaned regularly.

Fresh water filter (in dual circuit systems):

• Present in engines that use a closed cooling system (fresh water inside and sea water outside).
• This filter keeps the fresh water circulating inside the engine clean.

When to replace or clean filters

1. Fuel/water separator filter : every 100 hours or once a year.
2. Raw water filter : Visually inspect each outlet and clean monthly or if you notice a drop in cooling water pressure.
3. Fresh water filter : if equipped, according to engine specifications.

Practical advice

• Keep a spare filter on board.
• Make sure the seals are always in good condition and well lubricated (seaweed or specific grease).
• Choose clear filters where possible for easier inspection.