Lower Case Gasket – Fits Yamaha 9.9HP & 15HP Outboards (Replaces 683-45315-A0-00)
Lower Case Gasket – Fits Yamaha 9.9HP & 15HP Outboards (Replaces 683-45315-A0-00) is backordered and will ship as soon as it is back in stock.
Couldn't load pickup availability
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
Lower Case Gasket – Fits Yamaha 9.9HP & 15HP Outboards (Replace...
Product Details
This aftermarket Lower Case Gasket is designed for a wide range of Yamaha 9.9HP and 15HP, 2-Stroke and 4-Stroke outboard engines. It provides a reliable, high-integrity seal for the engine's lower unit, preventing leaks and ensuring proper performance.
It serves as a direct interchange for Yamaha part numbers 683-45315-A0-00, 683-45315-A0, 683-45315-00-00, and is also cross-referenced with Sierra part 18-99152.
- Installs on the engine lower unit housing to create a secure seal.
- Constructed from a durable paper/composite material to resist oil and water.
- Critical for maintaining the integrity of the engine's internal sealing system.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket suppliers.
| Brand | Part Number |
|---|---|
| Yamaha | 683-45315-A0-00 |
| Yamaha | 683-45315-A0 |
| Yamaha | 683-45315-00-00 |
| Sierra | 18-99152 |
Engine & Model Compatibility
Confirm your engine model and horsepower in the table below. It is critical to verify your specific OEM part number before ordering.
| Brand | Model | Rated HP | Stroke | OEM Part No. | Notes |
|---|---|---|---|---|---|
| Yamaha | Various | 9.9 | 2-Stroke & 4-Stroke | 683-45315-A0-00 | Also fits 15HP models |
| Yamaha | Various | 15 | 2-Stroke & 4-Stroke | 683-45315-A0-00 |
Technical Specs
- Product Type
- Lower Case Gasket / Packing
- Installation
- Engine Lower Unit
- Housing Material
- Paper / Composite
- Housing Color
- Green
- Dimensions
- 7.5" L x 11.0" W x 0.2" H
- Weight
- 50 g (0.11 lb)
- Other Technical Attributes
- Used for engine sealing system
What’s in the Box
- 1 x Packing, Lower Case (Replaces 683-45315-A0-00 / 683-45315-A0 / 683-45315-00-00)
Installation Notes
Generic installation process. Refer to your engine's official service manual for detailed instructions and torque specifications.
- Disconnect the spark plug leads and battery for safety.
- Position a drain pan under the lower unit and remove the gearcase oil drain and vent screws to drain the oil completely.
- Remove the mounting bolts securing the lower unit to the engine's upper casing.
- Carefully detach the lower unit from the engine. You may need to gently tap it with a rubber mallet to free it.
- Remove the old lower case gasket and meticulously clean both mating surfaces of any old gasket material, sealant, or corrosion.
- Position the new gasket correctly onto the lower unit.
- Re-attach the lower unit, ensuring it aligns properly. Tighten the bolts in a crisscross pattern to the manufacturer's recommended torque.
- Reinstall the gearcase drain and vent screws (using new washers if required) and refill with the correct type and amount of marine gear oil.
Troubleshooting & FAQ
How do I confirm this gasket fits my specific engine?
This gasket fits a wide variety of Yamaha 9.9HP and 15HP outboard models. The best way to ensure compatibility is to match the OEM part number 683-45315-A0-00 to the one listed in your engine's service manual or by inspecting your existing part.
What are the signs of a failing lower case gasket?
Common signs include visible oil leaks between the lower unit and the engine housing, or milky/creamy gear oil, which indicates water intrusion. A damaged gasket should be replaced whenever the lower unit is serviced.
Is any sealant required with this gasket?
Typically, this type of gasket is designed to be installed dry. However, always consult your motor's service manual, as some specific models may recommend a light application of a non-hardening sealant.
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 and specifications against 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
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
