Washer, Vent Screw (.187 x .500 x .062) – Fits Mercury/Mercruiser Marine Engines (Replaces 12-49221)
Washer, Vent Screw (.187 x .500 x .062) – Fits Mercury/Mercruiser Marine Engines (Replaces 12-49221) 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
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Washer, Vent Screw (.187 x .500 x .062) – Fits Mercury/Mercruiser M...
Product Details
This is a replacement Washer, Vent Screw (.187 x .500 x .062) for a wide range of Mercury and Mercruiser marine applications. It is designed to fit various Mercury outboard engines from 45HP to 225HP (1967–Current) and also works with select MerCruiser sterndrive and inboard models, providing a reliable seal for the vent screw.
This part directly replaces Mercury OEM part numbers 12-49221 and 12-8M0204663, and is interchangeable with Sierra 18-2948, Mallory 9-43629, and GLM 31180.
- Made from durable neoprene rubber to ensure a proper seal and prevent leaks.
- Precision-cut to OEM specifications for a direct-fit replacement.
- Essential for routine gearcase lubricant changes and maintenance.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Superseded By |
|---|---|---|
| Mercury | 12-49221 | 12-8M0204663 |
| Mercury | 12-492211 | 12-8M0204663 |
| Sierra | 18-2948 | |
| Mallory | 9-43629 | |
| GLM | 31180 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
Mercury Outboard Applications
| Model | Rated HP | Years | OEM Part No. |
|---|---|---|---|
| 45 JET | 45 | 1967–Current | 12-49221/12-8M0204663 |
| 50 (3 CYL.) | 50 | 1967–Current | 12-49221/12-8M0204663 |
| 55 (3 CYL.) | 55 | 1967–Current | 12-49221/12-8M0204663 |
| 60 (2 CYL.) | 60 | 1967–Current | 12-49221/12-8M0204663 |
| 60 (3 CYL.) | 60 | 1967–Current | 12-49221/12-8M0204663 |
| 65 JET | 65 | 1967–Current | 12-49221/12-8M0204663 |
| 75 (3 CYL.) | 75 | 1967–Current | 12-49221/12-8M0204663 |
| 80 JET | 80 | 1967–Current | 12-49221/12-8M0204663 |
| 90 (3 CYL.) | 90 | 1967–Current | 12-49221/12-8M0204663 |
| 100 (4 CYL.) | 100 | 1967–Current | 12-49221/12-8M0204663 |
| 115 (4 CYL.) | 115 | 1967–Current | 12-49221/12-8M0204663 |
| 125 (4 CYL.) | 125 | 1967–Current | 12-49221/12-8M0204663 |
| 140 JET | 140 | 1967–Current | 12-49221/12-8M0204663 |
| V-135, V-150, V-175, V-200 | 135-200 | 1967–Current | 12-49221/12-8M0204663 |
| 150 EFI PRO MAX/SUPER MAG | 150 | 1967–Current | 12-49221/12-8M0204663 |
| 200 EFI PRO MAX/SUPER MAG | 200 | 1967–Current | 12-49221/12-8M0204663 |
| 225 EFI PRO MAX/SUPER MAG | 225 | 1967–Current | 12-49221/12-8M0204663 |
Mercury Jet Drive Applications
| Model | Rated HP | Years | OEM Part No. |
|---|---|---|---|
| 175XR2 JET DRIVE | 175 | 1967–Current | 12-49221/12-8M0204663 |
| 210 CARB JET DRIVE | 210 | 1967–Current | 12-49221/12-8M0204663 |
| 240 EFI JET DRIVE | 240 | 1967–Current | 12-49221/12-8M0204663 |
Mercury Inboard/Sterndrive Applications
| Model | Years | OEM Part No. |
|---|---|---|
| 525 EFI | 1967–Current | 12-49221/12-8M0204663 |
| 565 EFI | 1967–Current | 12-49221/12-8M0204663 |
| 600 SCi | 1967–Current | 12-49221/12-8M0204663 |
| 662 SCi | 1967–Current | 12-49221/12-8M0204663 |
| 700 SCi | 1967–Current | 12-49221/12-8M0204663 |
Technical Specs
- Product Type
- Neoprene Rubber Washer
- Application
- Vent Screw Washer
- Material
- Neoprene Rubber
- Dimensions
- .187" ID x .500" OD x .062" Thickness (4.75mm x 12.7mm x 1.57mm)
- Weight
- 4.54g (0.16 oz)
- Color
- Black
- OEM Part Number
- Mercury 12-49221
- Superseded By
- 12-8M0204663
- UPC
- 745061157026
What’s in the Box
- 1 x Washer, Vent Screw (12-49221)
Installation Notes
- Ensure the engine is off and the drive unit is cool to the touch.
- Position a drain pan under the gearcase vent screw.
- Using a large flathead screwdriver, carefully loosen and remove the vent screw.
- Remove and discard the old washer from the screw.
- Clean any debris from the screw threads and the sealing surface on the gearcase.
- Place the new washer onto the vent screw.
- Reinstall the screw and tighten it snugly. Do not overtighten, as this can damage the washer or gearcase.
Troubleshooting & FAQ
How do I know if this washer fits my specific engine?
While this washer is compatible with a broad range of Mercury and Mercruiser models from 1967 to present, the best way to ensure fitment is to check your engine's service manual or existing part for the number 12-49221. If your old part matches this number, our washer is a direct replacement.
What are the signs of a failing vent screw washer?
A primary sign of a bad washer is a visible oil or lubricant leak around the vent screw. Another critical indicator is milky or creamy-looking gear lubricant when you drain it, which signifies water has entered the gearcase through a failed seal.
How often should I replace this washer?
It is highly recommended to use a new washer every time you remove the vent screw. This is most commonly done during a seasonal gear lubricant change. Reusing an old, compressed washer dramatically increases the risk of leaks.
Can I reuse the old washer in an emergency?
Reusing old washers is not recommended as they compress and harden, losing their ability to create a reliable seal. While it might work temporarily, it should be replaced with a new one as soon as possible to prevent water intrusion and lubricant loss.
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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