Sierra FUEL FILTER 21MIC LONG SIE-18-7845
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You have 30 days to request a return. All sale items are final sale.
The Sierra 18-7845 is a marine fuel/water separating spin-on filter designed for gasoline applications and built to help protect the fuel system from water and larger contaminants before they reach the engine. This is the long canister, 21 micron version, making it a practical replacement when you want primary fuel filtration in compatible marine fuel filter assemblies. Sierra lists it as a direct replacement for selected Mallory, MerCruiser sterndrive, Mercury, Quicksilver, and Yamaha outboard filters.
Key Features
- Genuine Sierra 18-7845 fuel/water separating filter
- 21 micron filtration rating
- Long spin-on canister design
- Designed for gasoline fuel filtration
- Rated for 90 GPH fuel flow
- Removes over 99.8% of emulsified water
- Meets ISO, SAE, and JIS standards
- Direct replacement for selected Mallory, MerCruiser sterndrive, Mercury, Quicksilver, and Yamaha outboard filters
Engine Compatibility
Commonly used in selected MerCruiser sterndrive, Mercury, Quicksilver, Yamaha outboard, and Mallory-style marine fuel filter/water separator applications that call for the 18-7845 long 21 micron element. Exact fitment still depends on the filter head, existing separator setup, and the engine or fuel-system application being serviced.
Serial Number Fitment Notice
Fitment should be confirmed by existing filter number, fuel separator assembly, and engine model/serial number before ordering. This is the long 21 micron version, so it should be matched carefully against the current installed filter or the separator kit specification.
When This Part Needs Replacement
Replace this filter during routine fuel-system service, when water or contamination is found in the separator, when fuel flow becomes restricted, or when the current element has reached its normal maintenance interval.
Installation Notes
Install this filter only in the correct compatible marine separator head. Confirm the replacement by part number before installation, and avoid mixing it with shorter canisters or finer-micron alternatives if the existing setup calls for the long 21 micron version. Clean the sealing surface and lubricate the gasket during installation as appropriate for standard spin-on filter service.
Alternate/Superseded Part Numbers
Sierra 18-7845 is listed as a direct replacement for selected Mallory, MerCruiser sterndrive, Mercury, Quicksilver, and Yamaha fuel filter references. Current seller references also associate it with Mercury/Quicksilver 35-802893Q01 in replacement use.
Parts Desk Insight
The biggest mistake on these filters is ordering by looks alone. Sierra makes both short and long versions, and both 10 and 21 micron options, so matching the old filter number first saves a lot of hassle.
Shipping: Ships same or next day for fast Canada wide shipping. ⚓
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.