Upper Casing Gasket – Fits Yamaha 9.9-15hp Outboards (Replaces 682-45113-A3-00, 682-45113-02)
Upper Casing Gasket – Fits Yamaha 9.9-15hp Outboards (Replaces 682-45113-A3-00, 682-45113-02) 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
Product Details
This Upper Casing Gasket provides a secure seal between the upper casing and the lower unit on a range of Yamaha 9.9–15hp, 2-Stroke outboards manufactured between 1984 and 2003. It is designed specifically for models including the 9.9D, 15D, E9.9D, and E15D series.
It serves as a direct interchange for Yamaha part numbers 682-45113-A3-00 and 682-45113-02, as well as Sierra 18-99022 and Mercury equivalents 96618 and 27-96618.
- Installs between the upper case and lower unit assembly.
- Secures via the main bolted housing assembly.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yamaha | 682-45113-A3-00 |
| Yamaha | 682-45113-A2-00 |
| Yamaha | 682-45113-A1-00 |
| Yamaha | 682-45113-02-00 |
| Yamaha | 682-45113-01-00 |
| Sierra | 18-99022 |
| Mercury | 96618 |
| Mercury | 27-96618 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Yamaha Owners: This gasket fits a wide range of 9.9hp and 15hp 2-stroke models made between 1984 and 2012. Verify your specific model code (e.g., 9.9D, E15DMH) against the list to ensure fitment.
For Mercury Owners: This part is a known crossover for several 2-stroke models including the 9.9C and 15C series. As year ranges are not fully specified, a visual match against your old part is essential.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | 9.9D (6E7) | 9.9 | 2-Stroke | 1985–1995 | 682-45113-A3-00 | Multiple series variants including 999, 030, 010 |
| Yamaha | 9.9EL/ES/L/S | 9.9 | 2-Stroke | 1984–1995 | 682-45113-A3-00 | Multiple letter suffixes N through T |
| Yamaha | E9.9D (6B31) | 9.9 | 2-Stroke | 2003 | 682-45113-A3-00 | Variants 020, 02A, 060, 06A, 110, 11A |
| Yamaha | E9.9DMH-S/DMHS | 9.9 | 2-Stroke | 2003 | 682-45113-A3-00 | Multiple variants |
| Yamaha | 15D (6E8) | 15 | 2-Stroke | 1985–1995 | 682-45113-A3-00 | Multiple series variants including 999, 040, 010, 030 |
| Yamaha | 15EL/ES/L/S | 15 | 2-Stroke | 1984–1995 | 682-45113-A3-00 | Multiple letter suffixes N through T |
| Yamaha | E15D (6B41) | 15 | 2-Stroke | 2003 | 682-45113-A3-00 | Multiple variants |
| Yamaha | E15DMH/DMHL/DMHS/DMHX | 15 | 2-Stroke | 2012 | 682-45113-A3-00 | Multiple variants |
| Mercury | 9.9C | 9.9 | 2-Stroke | 27-96618 | ||
| Mercury | 15C | 15 | 2-Stroke | 27-96618 | ||
| Mercury | 15K | 15 | 2-Stroke | 27-96618 | ||
| Mercury | W15 | 15 | 2-Stroke | 27-96618 |
Technical Specs
- Product Type
- Upper Casing Gasket
- Installation Location
- Between upper case and lower unit
- Connection
- Bolted assembly
- Dimensions
- 31.0 cm L x 21.0 cm W x 0.5 cm H
- Warranty
- Standard manufacturer warranty
What’s in the Box
- 1 x Upper Casing Gasket (Replaces 682-45113-A3-00)
Installation Notes
- Ensure the engine is off, cool, and the battery is disconnected. Place a drain pan under the lower unit.
- Remove the gearcase drain and vent screws to drain the gear lubricant completely.
- Unbolt the lower unit from the upper engine casing and carefully separate the two halves.
- Remove the old gasket and thoroughly clean both mating surfaces. Ensure they are free of any old gasket material, sealant, or corrosion.
- Position the new gasket correctly on the mounting surface, aligning all bolt holes.
- Reassemble the lower unit to the upper casing. Tighten the bolts in the sequence and to the torque values specified in your engine's service manual.
- Install new washers on the drain and vent screws, then refill the gearcase with the correct type and amount of lubricant before operation.
Troubleshooting & FAQ
How do I know if this is the right gasket for my engine?
The most reliable method is to match your engine's model number and year to our compatibility table. Cross-referencing your old part number with our Part Number Matrix is also a valid confirmation step. When in doubt, compare our product photos with your existing part.
What are the signs of a failed upper casing gasket?
Common symptoms include water contaminating the gearcase oil (giving it a milky appearance), oil leaking externally from the seam between the lower unit and upper casing, or a loss of pressure during a gearcase pressure test.
What is the difference between all the Yamaha part numbers listed?
The various Yamaha part numbers (e.g., 682-45113-A3-00, 682-45113-02-00) represent a supersession chain. Newer numbers replace older ones, but all are functionally identical for the specified applications. This gasket is a direct replacement for all of them.
Is any sealant required with this gasket?
Typically, this type of gasket is designed to be installed dry. However, always consult your engine's service manual, as some applications may recommend a light application of a specific non-hardening sealant.
Can I reuse my old gasket?
No. Casing gaskets are single-use, crush-style components. Reusing an old gasket will almost certainly result in leaks and can lead to severe damage to your lower unit and engine.
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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