Sierra Fuel Filter 21-Micron Medium (1"-12 Thread) Spin-On Replacement for Marine Engines

Sierra International 18-7846 is a medium, 21-micron replacement fuel filter with 1"-12 thread designed to fit a wide range of marine and sterndrive engines.

This replacement fuel filter is engineered to match the fit and filtration performance of common OEM items including OMC 502905, CRUSADER 98041, OMC 174144, and VOLVO 3851218-2. With a 21-micron rating and standard 1"-12 thread pitch, the part serves as a universal-fit service item for many sterndrive and inboard/outboard systems. Sierra backs the part with its customer satisfaction warranty and provides an alternative to manufacturer-specific cartridges for routine maintenance and repairs.

How does the 21-micron rating affect fuel cleanliness?

A 21-micron filter captures medium-sized particulates that can harm fuel system components without restricting flow excessively. It balances filtration and engine performance, helping to keep injectors, carburetors, and pump components freer of abrasive debris.

• Rated to remove particles down to 21 microns in size
• Designed to reduce contaminant build-up in fuel pumps and injectors
• Maintains adequate fuel flow for typical marine engine demands

Will this replace my OEM filter (which models does it fit)?

The Sierra 18-7846 is a direct-style replacement for several OEM part numbers and is built to match their thread and filtration specifications. It is compatible with OMC and Volvo part references and fits many Crusader applications when the listed OEM numbers correspond to your existing filter.

• Cross-references: OMC 502905, OMC 174144, CRUSADER 98041
• Also compatible with VOLVO 3851218-2 where a 21-micron, 1"-12 thread is required
• Universal-fit design simplifies aftermarket replacements

How do I install and maintain this filter?

Installation follows the same steps as most spin-on fuel filters: drain or relieve fuel pressure, unscrew the old filter, apply a light oil film to the new filter gasket, and hand-tighten. Replace at regular service intervals or whenever contamination or water in fuel is suspected.

• Thread pitch: 1"-12 — confirm thread compatibility with your mounting base
• Hand-tighten and follow engine manufacturer torque guidance if available
• Inspect for leaks after startup and replace if damaged or clogged

What warranty and support does Sierra provide?

Sierra covers this part under its customer satisfaction warranty, reflecting the company's support for aftermarket marine replacement parts. Warranty specifics follow Sierra's terms, and support is available for installation or fitment questions.

• Included in Sierra's industry-standard customer satisfaction warranty
• Technical help available for fit and cross-reference inquiries
• Replacement or return policies handled per Sierra's warranty terms

Who this product is for: Boat owners, mechanics, and marine service shops looking for a reliable, medium-rated replacement fuel filter that matches OMC, Crusader, and Volvo part references. Choose the Sierra 18-7846 if you need a 21-micron, 1"-12 thread spin-on filter for routine maintenance, retrofit projects, or to keep older sterndrive and inboard/outboard fuel systems running cleanly. Always confirm compatibility with your engine's service manual or existing filter part number before ordering.