Washer – Fits Mercury/Mariner 3.5 HP–300 HP and MerCruiser (Replaces 12-77674)
Washer – Fits Mercury/Mariner 3.5 HP–300 HP and MerCruiser (Replaces 12-77674) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Washer – Fits Mercury/Mariner 3.5 HP–300 HP and MerCruiser (Replace...
Product Details
This replacement Washer is designed for a broad range of Mercury/Mariner 2-stroke and 4-stroke outboard engines, from 3.5 HP to 300 HP, covering models from the early 1970s to the present. It is also compatible with MerCruiser stern drives manufactured from 1996 onwards.
This component serves as a direct replacement for Mercury/Mercruiser part number 12-77674.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury/Mercruiser | 12-77674 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury/Mariner outboards, this part fits a wide variety of 2-stroke and 4-stroke models, including Jet, EFI, DFI, and Verado series engines.
For MerCruiser stern drives, compatibility includes Alpha One (Gen II), Vazer Drive, and Vazer Transom models from 1996 to current.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury/Mariner | 30 JET | 30 | 2-Stroke | 1996–Up | 12-77674 | |
| Mercury/Mariner | 35 | 35 | 2-Stroke | 1970–Up | 12-77674 | |
| Mercury/Mariner | 40 | 40 | 2-Stroke | 1975–Up | 12-77674 | |
| Mercury/Mariner | 45 | 45 | 2-Stroke | 1976–Up | 12-77674 | |
| Mercury/Mariner | 50 | 50 | 2-Stroke | 1972–Up | 12-77674 | |
| Mercury/Mariner | 60 | 60 | 2-Stroke | 1986–Up | 12-77674 | |
| Mercury/Mariner | 65 JET | 65 | 2-Stroke | 1995–Up | 12-77674 | |
| Mercury/Mariner | 70 | 70 | 2-Stroke | 1976–Up | 12-77674 | |
| Mercury/Mariner | 75 | 75 | 2-Stroke | 1987–Up | 12-77674 | |
| Mercury/Mariner | 80 | 80 | 2-Stroke | 1977–Up | 12-77674 | |
| Mercury/Mariner | 80 JET | 80 | 2-Stroke | 1994–Up | 12-77674 | |
| Mercury/Mariner | 90 | 90 | 2-Stroke | 1987–Up | 12-77674 | |
| Mercury/Mariner | 100 (4 CYL.) | 100 | 2-Stroke | 1994–Up | 12-77674 | |
| Mercury/Mariner | 100 EFI | 100 | 4-Stroke | 2004–Up | 12-77674 | |
| Mercury/Mariner | 105 JET | 105 | 2-Stroke | 1994–Up | 12-77674 | |
| Mercury/Mariner | 110 JET | 110 | 2-Stroke | 2006–Up | 12-77674 | |
| Mercury/Mariner | 115 (4 CYL.) | 115 | 2-Stroke | 1994–Up | 12-77674 | |
| Mercury/Mariner | 115 (6 CYL.) | 115 | 2-Stroke | 1973–Up | 12-77674 | |
| Mercury/Mariner | 115 EFI | 115 | 4-Stroke | 2004–Up | 12-77674 | |
| Mercury/Mariner | 125 (4 CYL.) | 125 | 2-Stroke | 1994–Up | 12-77674 | |
| Mercury/Mariner | 135 VERADO | 135 | 4-Stroke | 2004–Up | 12-77674 | |
| Mercury/Mariner | 135 DFI | 135 | 2-Stroke | 1998–Up | 12-77674 | |
| Mercury/Mariner | 140 | 140 | 2-Stroke | 1978–Up | 12-77674 | |
| Mercury/Mariner | 140 JET | 140 | 2-Stroke | 1994–Up | 12-77674 | |
| Mercury/Mariner | 150 | 150 | 2-Stroke | 1978–Up | 12-77674 | |
| Mercury/Mariner | 150 PRO XS | 150 | 2-Stroke | 2006–Up | 12-77674 | |
| Mercury/Mariner | 150 VERADO | 150 | 4-Stroke | 2004–Up | 12-77674 | |
| Mercury/Mariner | 175 | 175 | 2-Stroke | 1976–Up | 12-77674 | |
| Mercury/Mariner | 175 PROXS | 175 | 2-Stroke | 2005–Up | 12-77674 | |
| Mercury/Mariner | 175 VERADO | 175 | 4-Stroke | 2004–Up | 12-77674 | |
| Mercury/Mariner | 200 | 200 | 2-Stroke | 1978–Up | 12-77674 | |
| Mercury/Mariner | 200 PRO VERADO | 200 | 4-Stroke | 2006–Up | 12-77674 | |
| Mercury/Mariner | 200 PRO XS | 200 | 2-Stroke | 2005–Up | 12-77674 | |
| Mercury/Mariner | 200 VERADO | 200 | 4-Stroke | 2004–Up | 12-77674 | |
| Mercury/Mariner | 225 | 225 | 2-Stroke | 1994–Up | 12-77674 | |
| Mercury/Mariner | 225 PRO XS | 225 | 2-Stroke | 2005–Up | 12-77674 | |
| Mercury/Mariner | 225 VERADO | 225 | 4-Stroke | 2004–Up | 12-77674 | |
| Mercury/Mariner | 250 | 250 | 2-Stroke | 1994–Up | 12-77674 | |
| Mercury/Mariner | 250 PRO VERADO | 250 | 4-Stroke | 2006–Up | 12-77674 | |
| Mercury/Mariner | 250 PRO XS | 250 | 2-Stroke | 2005–Up | 12-77674 | |
| Mercury/Mariner | 250 VERADO | 250 | 4-Stroke | 2004–Up | 12-77674 | |
| Mercury/Mariner | 275 VERADO | 275 | 4-Stroke | 2004–Up | 12-77674 | |
| Mercury/Mariner | 300 PRO VERADO | 300 | 4-Stroke | 2006–Up | 12-77674 | |
| Mercury/Mariner | 300 VERADO | 300 | 4-Stroke | 2005–Up | 12-77674 | |
| MerCruiser | ALPHA ONE (GEN.II) | 1996–Up | 12-77674 | GEN.II models only | ||
| MerCruiser | VAZER DRIVE | 2005–Up | 12-77674 | |||
| MerCruiser | VAZER TRANSOM | 2005–Up | 12-77674 |
Technical Specs
- Product Type
- Washer
- Dimensions
- Length: 1.0 in
Width: 5.13 in
Height: 4.0 in - Weight
- 0.027 kg (0.06 lb)
What’s in the Box
- 1 x WASHER (12-77674)
Installation Notes
- Disconnect the engine's battery as a safety precaution.
- Locate and access the assembly where the old washer is situated, such as the shift shaft or gear housing.
- Carefully remove the fasteners and components to take out the worn or damaged washer.
- Thoroughly clean the surfaces of the components that will contact the new washer, removing any old sealant, corrosion, or debris.
- Place the new washer into its correct position, ensuring proper alignment.
- Reassemble the related components, tightening all bolts and fasteners to the manufacturer's recommended torque specifications.
- After reassembly, reconnect the battery and test the engine's operation to ensure everything functions correctly.
Troubleshooting & FAQ
How do I know if this washer fits my specific engine model?
This washer has extensive compatibility. The best way to confirm a fit is to cross-reference your engine's original part number with 12-77674. You can also check the detailed compatibility table on this page to find your engine model, horsepower, and year range.
What are the signs of a failing or worn-out washer?
Signs of a failing washer can include leaks (oil or water), loose-fitting components, unusual vibrations, or difficulty shifting gears, depending on its specific location within the engine or drive assembly. Visual inspection during maintenance may also reveal corrosion, cracks, or deformation.
Is this part difficult to install?
The difficulty depends on the washer's location. If it is easily accessible, installation can be straightforward. However, if it requires significant disassembly of the lower unit or other complex components, professional installation is recommended to ensure proper sealing and function.
What is this washer's primary function?
This washer is typically used in gearcase and drive assemblies, often on shift shafts or as a seal/spacer between critical moving parts. It ensures correct spacing, provides a seal, and prevents wear between components.
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.
Payment & Security
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