Sierra 18-7946 Fuel Water Separator Filter, 10 Micron, OMC Thread, Replaces OMC 502905

The Sierra 18-7946 is a 10 micron fuel water separator filter built with an OMC thread configuration and a metal outer housing. It is designed to trap water and contaminants out of the fuel supply before they reach the engine, protecting fuel injectors, carburetors, and internal fuel system components from corrosion and debris damage. The filter uses a 1 inch-12 thread pitch for direct installation onto compatible fuel water separator housings.

This filter is part of Sierra's 10 micron OMC-thread filter line and directly replaces OMC 502905. It is intended for vehicle service on Mercruiser applications. Routine replacement of the fuel water separator filter helps maintain consistent fuel flow and protects against ethanol-related moisture contamination, a common issue in marine fuel systems.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-7946
• Description: OMC thread
• Micron Rating: 10 Micron
• Thread Pitch: 1 inch-12
• Outer Material: Metal
• Weight: 1.09 pounds
• Vehicle Service Type: Mercruiser
• Unit Count: 1
• UPC: 808282201876

Fitment

Vehicle service type: Mercruiser.

Replaces (OEM)

• OMC 502905

Frequently Asked Questions

What is the micron rating of the Sierra 18-7946 filter? The Sierra 18-7946 fuel water separator filter has a 10 micron rating.

Does the Sierra 18-7946 replace an OMC part number? Yes, the Sierra 18-7946 directly replaces OMC 502905.

What thread size does the 18-7946 filter use? It uses a 1 inch-12 thread pitch, matching the OMC thread configuration it is built for.

What is the outer housing material of this filter? The Sierra 18-7946 has a metal outer housing.

How much does the Sierra 18-7946 filter weigh? The Sierra 18-7946 fuel water separator filter weighs 1.09 pounds.

What vehicle service type is the 18-7946 filter used for? The Sierra 18-7946 is listed for Mercruiser vehicle service.

How many filters come in the package? The Sierra 18-7946 is sold as a single unit, one filter per package.

What is the difference between the 18-7946 and the 18-7846 filter? The 18-7946 is the 10 micron OMC-thread version, while the 18-7846 is the 21 micron version of the same OMC-thread filter design.

Is there a Cobra EFI version of this filter? Yes, the 10 micron Cobra EFI equivalent to the OMC-thread 18-7946 is the Sierra 18-7989, which replaces OMC 502906.

Is the Sierra 18-7946 a genuine Sierra part or aftermarket? The 18-7946 is a Sierra manufactured filter engineered as a direct replacement for OMC 502905, not an OEM-branded part.

What does the 18-7946 filter protect against? As a fuel water separator filter, the 18-7946 removes water and contaminants from fuel before it reaches the engine's fuel system.

Can I identify the 18-7946 filter by its UPC? Yes, the Sierra 18-7946 filter carries UPC 808282201876.