Sierra 18-7983 Mercury Fuel/Water Separator Filter - Available as Kit or Filter with Bonus Pack

The Sierra 18-7983 is a 10 micron fuel/water separator filter built for Mercury outboard fuel injected engines, designed to protect sensitive fuel injection components from water contamination and debris. The filter uses a 1/4 inch aluminum short-filter housing and removes over 99.8 percent of emulsified water from gasoline while filtering out over 90 percent of particles as small as 10 microns. Rated to flow up to 90 gallons per hour, it supplies enough clean, dry fuel for high-demand outboard motors without restricting flow.

Each build includes the core filter element (18-7944) along with the mounting base/seal component (18-7853-1), giving you a complete water-separating assembly rather than just a replacement cartridge. It is engineered as a direct match for a wide range of Mercury outboards, cross-referencing to numerous Mercury OEM part numbers, so it installs as a factory-equivalent solution. The 18-7983 is offered in two configurations so you can choose the complete kit or a filter that comes bundled with a bonus item, depending on whether you are doing a first-time install or a routine filter change.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-7983
• Product Type: Fuel/Water Separator Filter
• Micron Rating: 10 Micron
• Outer Material: Aluminum
• Filter Housing Length: Short Filter
• Filter Diameter/Thread Size: 1/4 inch (6.4mm)
• Flow Rate: 90 Gallons Per Hour
• Water Removal Efficiency: Over 99.8 percent of emulsified water
• Particle Filtration Efficiency: Over 90 percent of particles as small as 10 micron
• Kit Contents: 1 filter element (18-7944) and 1 base/seal component (18-7853-1)
• Fit Type: Universal Fit for compatible Mercury outboards
• OEM Cross Reference: Mercury 35-802893A4, Q4, 35-60494A4, 35-807172A4, 35-60494A1, 35-57250A1, 35-55501A1, 35-52456A1

Sizes & Options

The Sierra 18-7983 line is available in two configurations. The Fuel/Water Separator Kit is the complete assembly, ideal for a first-time installation or when the mounting base needs replacing along with the filter. The Filter with Bonus Pack version is intended for buyers who already have the base assembly installed and need a replacement filter, and it ships with an extra bonus item included. Choose based on whether you need the full assembly or just a filter replacement.

Frequently Asked Questions

What micron rating does the Sierra 18-7983 filter use? The Sierra 18-7983 fuel/water separator filter uses a 10 micron element, which is over 90 percent efficient at removing particles as small as 10 microns from the fuel stream.

How much water can the 18-7983 remove from fuel? It removes over 99.8 percent of emulsified water from gasoline, protecting fuel injected engines from water-related damage.

What is the flow rate of the Sierra 18-7983? This filter flows at up to 90 gallons per hour, enough capacity to feed high-demand outboard motors without restricting fuel delivery.

What Mercury OEM part numbers does the 18-7983 replace? The 18-7983 cross-references to Mercury 35-802893A4, Q4, 35-60494A4, 35-807172A4, 35-60494A1, 35-57250A1, 35-55501A1, and 35-52456A1.

What size fitting does this filter use? The Sierra 18-7983 has a 1/4 inch (6.4mm) fitting size and uses an aluminum short-filter housing.

Should I choose the Kit or the Filter with Bonus Pack? Choose the Fuel/Water Separator Kit if you need the complete assembly including the base/seal component, such as for a first-time installation; choose the Filter with Bonus Pack if you already have the base installed and just need a replacement filter, since it comes with an extra bonus item included.

What is included with the 18-7983 kit? The kit configuration of the Sierra 18-7983 includes one filter element (18-7944) and one base/seal component (18-7853-1).

Is the Sierra 18-7983 a genuine Sierra part or an aftermarket equivalent? The 18-7983 is manufactured by Sierra as a direct-fit aftermarket replacement engineered to Mercury OEM specifications, not a repackaged factory part.

What material is the filter housing made of? Both configurations of the 18-7983 use an aluminum outer housing in the short-filter length.

Will this filter work with fuel injected outboard engines? Yes, the Sierra 18-7983 is designed specifically to protect sensitive inboard, sterndrive, and outboard fuel injection systems from water and particulate contamination.

How is the 18-7983 different from other Sierra fuel/water separators like the 18-7982-1? The 18-7983 uses a short aluminum filter housing with a 1/4 inch fitting and a 10 micron rating, distinguishing it from other Sierra separators that use a tall housing, a different fitting size, or stainless steel construction.

Does the filter need to be replaced on a schedule? Fuel/water separator filters like the Sierra 18-7983 are a routine maintenance item and should be replaced periodically as part of regular engine service to maintain the rated 90 gallon-per-hour flow and filtration efficiency.