Mercury MerCruiser Quicksilver Seawater Pump Washer 20084 – Pack of 5
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Mercury / MerCruiser Seawater Pump Washer 20084 – Pack of 5
Part Number: 20084 | Service Format: 12-20084 | Pack Quantity: 5 washers | GTIN: 745061054721
Genuine Mercury / MerCruiser OEM flat washer, sold in a pack of 5. One of its primary documented applications is the MerCruiser engine-mounted seawater pump, where Mercury parts diagrams specify exactly five 20084 washers beneath the five retaining screws on applicable 807151-series pump assemblies — making this pack the right quantity for a complete pump service. Note: 20084 is a shared Mercury hardware number that also appears in other assemblies; always confirm the diagram position and part number for your specific application before ordering.
Specifications
- Brand: Mercury / MerCruiser / Quicksilver
- Part Number: 20084
- Service Format: 12-20084
- Type: Flat washer
- Inside Diameter: ~0.328 in. (8.33 mm)
- Outside Diameter: ~0.562 in. (14.27 mm)
- Thickness: ~0.062 in. (1.57 mm)
- Pack Quantity: 5 washers
- GTIN / UPC: 745061054721
- System: MerCruiser seawater (raw water) pump; also used in other Mercury assemblies
- Superseded By: No confirmed newer OEM superseding number identified
Compatible Applications
Fitment must be confirmed against the Mercury parts diagram for your specific engine model and serial number. Washer dimensions and material vary across assembly locations — always match by diagram part number, not by measurement alone.
- MerCruiser 807151A8 Sea Water Pump Assembly — qty 5 per assembly (beneath retaining screws)
- MerCruiser 807151A12 Water Pump Assembly — qty 5 per assembly (beneath retaining screws)
- Earlier related 72774-series seawater pump configurations (verify by diagram)
- Selected MerCruiser 4.3L V6, 7.4L V8, 8.2L V8, 454 MAG, 502 MAG inboard/sterndrive packages — depending on serial number and cooling configuration
- Other Mercury assemblies where 20084 appears on the parts diagram — confirm position and qty before ordering
When to Replace
- Washer is corroded, bent, distorted, or gouged around the mounting surface
- Washer is no longer seating evenly beneath the retaining screw head
- Washers go missing during pump disassembly — easy to lose overboard
- During any seawater-pump rebuild — replace all five as a set rather than individual pieces
Installation Notes
- For applicable 807151-series seawater pumps: install one 20084 washer beneath each of the five retaining screws
- Mercury diagrams pair these washers with retaining screw 99347 on certain pump assemblies
- Clean all mating surfaces before assembly
- Torque retaining screws to the specification in the Mercury service manual for the exact pump assembly being serviced — do not use a generic fastener torque value
Related Parts & Service Items
- Mercury Washer 20086 (Pack of 5) — companion washer used in related Mercury assemblies
- Mercury Quicksilver Washer 20583
- Mercury MerCruiser Washer Assembly 12-55073A2
- Mercury Quicksilver Propeller Shaft Thrust Washer 18448
Parts Desk Insights
Best use case: This five-pack is sized precisely for a complete 807151-series seawater pump service — buy one pack and you have the full set of washers for the job without counting out individual pieces. It's also smart to keep a spare pack on hand; washers this small are easy to drop overboard during a pump service, and having extras prevents a minor setback from turning into a delayed launch.
Common customer issue: Ordering washers by dimension rather than by diagram part number. 20084 is a shared hardware number across multiple Mercury assemblies, and similarly sized washers can differ in material, plating, and load rating. The safest approach is always to match the part number shown in your engine's parts diagram to the exact position you're servicing. If you're unsure which washer goes where, our parts desk can help you read the diagram.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
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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.
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