Fuel Water Separating Filter – Fits Mercury Marine V6 EFI/DFI Outboards (Replaces 35-18458Q4)
Fuel Water Separating Filter – Fits Mercury Marine V6 EFI/DFI Outboards (Replaces 35-18458Q4) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
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Delivery and Shipping
Free standard shipping on all orders under 1 KG
Fuel Water Separating Filter – Fits Mercury Marine V6 EFI/DFI Outbo...
Product Details
This high-efficiency Fuel Water Separating Filter – Fits Mercury Marine V6 EFI/DFI Outboards (Replaces 35-18458Q4) is essential for protecting your engine from water-contaminated gasoline. It is specifically designed for Mercury Marine V6 EFI (2.5L/3.0L) and DFI (2.5L/3.0L) outboard models from 1996 and newer, ensuring clean fuel delivery and preventing fuel system damage.
This filter serves as a direct replacement for Mercury Marine part numbers 35-18458Q4 and 35-18458, as well as Sierra 18-7968.
- Features a simple spin-on installation process for quick replacement.
- Includes the necessary blue screw-in water sensing probe for early contamination alerts.
- Removes over 99.8% of emulsified water from gasoline at a flow rate of up to 90 GPH.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury Marine | 35-18458Q4 |
| Mercury Marine | 35-18458 |
| Sierra | 18-7968 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury/Mariner models, this filter fits a wide range of V6 EFI and DFI outboards from 1996 and newer, and is typically located under the engine cowl.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | V-150 EFI (2.5L) | 150 | 4-Stroke | 1996-Up | 35-18458Q4 | Located under cowl |
| Mercury | V-175 EFI (2.5L) | 175 | 4-Stroke | 1996-Up | 35-18458Q4 | Located under cowl |
| Mercury | V-200 EFI (2.5L) | 200 | 4-Stroke | 1996-Up | 35-18458Q4 | Located under cowl |
| Mercury | V-135 DFI (2.5L) | 135 | 4-Stroke | 1996-Up | 35-18458Q4 | Located under cowl |
| Mercury | V-150 DFI (2.5L) | 150 | 4-Stroke | 1996-Up | 35-18458Q4 | Located under cowl |
| Mercury | V-175 DFI (2.5L) | 175 | 4-Stroke | 1996-Up | 35-18458Q4 | Located under cowl |
| Mercury | 200 DFI | 200 | 4-Stroke | 1996-Up | 35-18458Q4 | Located under cowl |
| Mercury | 225 DFI | 225 | 4-Stroke | 1996-Up | 35-18458Q4 | Located under cowl |
| Mercury | 200 (3.0L EFI) | 200 | 4-Stroke | 1996-Up | 35-18458Q4 | Located under cowl |
| Mercury | 225 (3.0L EFI) | 225 | 4-Stroke | 1996-Up | 35-18458Q4 | Located under cowl |
| Mercury | 250 (3.0L EFI) | 250 | 4-Stroke | 1996-Up | 35-18458Q4 | Located under cowl |
| Mercury | 225 (3.0L EFI) MARATHON | 225 | 4-Stroke | 1996-Up | 35-18458Q4 | Located under cowl |
| Mercury | 225 (3.0L EFI) SEAPRO | 225 | 4-Stroke | 1996-Up | 35-18458Q4 | Located under cowl |
| Mercury | 250 LONG (3.0L)(EFI) | 250 | 4-Stroke | 1996-Up | 35-18458Q4 | Located under cowl |
| Mercury | 3.0L EFI MARATHON | N/A | 4-Stroke | 1996-Up | 35-18458Q4 | Located under cowl |
| Mercury | 3.0L EFI SEAPRO | N/A | 4-Stroke | 1996-Up | 35-18458Q4 | Located under cowl |
| Mercury | RACE OUTBOARD 200XS DFI (2.5L) | 200 | 4-Stroke | 1996-Up | 35-18458Q4 | Located under cowl |
| Mercury | RACE OUTBOARD 225X EFI PROMAX | 225 | 4-Stroke | 1996-Up | 35-18458Q4 | Located under cowl |
| Mercury | RACE OUTBOARD 300X (3.0L EFI) PRO MAX | 300 | 4-Stroke | 1996-Up | 35-18458Q4 | Located under cowl |
For SportJet models, this filter is compatible with various Jet Drive models utilizing Mercury powerheads from 1996 and newer.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| SportJet | 200 DFI JET DRIVE | 200 | 4-Stroke | 1996-Up | 35-18458Q4 | Powerhead & Pump applications |
| SportJet | 200 DFI M2 JET DRIVE | 200 | 4-Stroke | 1996-Up | 35-18458Q4 | Powerhead & Pump applications |
| SportJet | 240 EFI JET DRIVE | 240 | 4-Stroke | 1996-Up | 35-18458Q4 | Powerhead & Pump applications |
| SportJet | 240 EFI M2 JET DRIVE | 240 | 4-Stroke | 1996-Up | 35-18458Q4 | Powerhead & Pump applications |
| SportJet | 250 DFI JET DRIVE | 250 | 4-Stroke | 1996-Up | 35-18458Q4 | Powerhead & Pump applications |
| SportJet | 250 DFI M2 JET DRIVE | 250 | 4-Stroke | 1996-Up | 35-18458Q4 | Powerhead & Pump applications |
Technical Specs
- Product Type
- Fuel Water Separating Filter
- Installation
- Spin-on
- Filtration Rating
- 10 micron
- Fuel Type
- Gasoline
- Connection
- Blue screw-in water sensing probe
- Dimensions
- 11.5 × 8.5 × 8.5 cm (approx. 4.5 × 3.3 × 3.3 in)
- Weight
- 0.9 kg (2 lbs)
- Flow Rate
- 90 GPH
- Water Separation
- Removes over 99.8% of emulsified water
What’s in the Box
- 1 x Fuel Water Separating Filter (Replaces 35-18458Q4)
- 1 x Water Sensing Probe (8285861)
Installation Notes
- Shut off the fuel supply. Place a suitable container below the filter to catch any fuel spillage.
- Carefully disconnect the water sensor wire from the base of the old filter.
- Using a filter wrench, unscrew and remove the old filter canister.
- Clean the filter mounting surface on the engine, ensuring the old gasket has been completely removed.
- Apply a thin layer of clean engine oil or fuel to the gasket of the new filter.
- Spin the new filter on by hand until the gasket makes firm contact with the mounting base.
- Tighten the filter an additional 3/4 to 1 full turn by hand. Do not overtighten.
- Reconnect the water sensor wire to the new filter.
- Prime the fuel system according to the engine manufacturer’s instructions.
- Start the engine and carefully inspect for any leaks around the filter housing.
Troubleshooting & FAQ
How do I know if this filter fits my engine?
This filter is designed for Mercury/Mariner V6 EFI and DFI outboards (2.5L/3.0L) from 1996 and newer. Please verify your engine model against the compatibility chart and confirm the OEM part number is 35-18458Q4. It is typically located under the engine cowl.
What is the purpose of the blue water sensor?
The included blue screw-in probe is a water-in-fuel (WIF) sensor. It connects to your engine's monitoring system to alert you when a significant amount of water has been separated from the fuel, indicating the filter needs to be drained or replaced.
How often should this fuel filter be replaced?
For optimal engine protection, it is recommended to replace your fuel water separating filter annually or every 100 hours of operation, whichever comes first. Refer to your engine's service manual for specific maintenance intervals.
What are the signs of a clogged or failing fuel filter?
Common symptoms include engine hesitation, loss of power, stalling, difficulty starting, or rough idling. Your engine's warning system may also trigger a water-in-fuel alert if the sensor detects excessive water.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost?
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns?
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
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