Gearcase Oil Seal – Fits OMC (Replaces 18-2028, 318973, 321480)
Gearcase Oil Seal – Fits OMC (Replaces 18-2028, 318973, 321480) 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
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
International delivery times may vary due to customs processing.
Tracking information will be provided once your order ships.
Gearcase Oil Seal – Fits OMC (Replaces 18-2028, 318973, 321480)
Gearcase Oil Seal – Fits OMC (Replaces 18-2028, 318973, 321480) is backordered and will ship as soon as it is back in stock.
Product Details
This Gearcase Oil Seal – Fits OMC (Replaces 18-2028, 318973, 321480) is designed as a direct-fit replacement for OMC marine engines requiring a reliable gearcase seal. Engineered to prevent fluid leaks and protect lower unit integrity, this seal ensures consistent performance across a range of OMC applications.
This aftermarket component directly replaces Sierra 18-2028, GLM 86170, OMC 318973, OMC 321480, OMC 0777541, and Mallory 9-76207.
- Single oil seal for gearcase applications
- Built to OEM specifications for reliable sealing
- Compatible with OMC marine engine lower units
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Sierra | 18-2028 |
| GLM | 86170 |
| OMC | 321480 |
| OMC | 0318973 |
| OMC | 0777541 |
| Mallory | 9-76207 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Application |
|---|---|
| OMC | Gearcase Oil Seal For OMC Marine Engine |
Technical Specs
- Part Type
- Gearcase Oil Seal
- OEM Numbers
- 2895, 321480, 318973
- Application
- OMC Marine Engine Lower Unit
- Quantity
- 1 piece
What's in the Box
- 1 × Oil Seal
Installation Notes
- Drain gearcase oil completely and clean the seal housing area of any old sealant or debris.
- Inspect the shaft for scoring or roughness that could damage the new seal.
- Lightly lubricate the seal lip with gearcase oil before installation.
- Press the seal squarely into the housing using an appropriately sized seal driver to avoid cocking.
- Ensure the seal is fully seated to the correct depth per manufacturer specifications.
- Refill gearcase with the recommended oil type and quantity.
- Check for leaks after initial operation and re-torque fasteners as needed.
Troubleshooting & FAQ
How do I know if my gearcase seal needs replacement?
Common signs include visible oil leaks around the lower unit, milky gearcase oil indicating water intrusion, or low oil levels between service intervals. Inspect seals during routine maintenance or whenever the lower unit is serviced.
Can I reuse an old seal during reassembly?
No. Once removed, oil seals lose their sealing integrity and should always be replaced with new ones to prevent leaks and contamination.
What causes premature seal failure?
Shaft damage, improper installation, contaminated oil, or running the lower unit dry can all cause seals to fail early. Always inspect mating surfaces and use clean, recommended lubricants.
Will this seal fit all OMC models?
This seal fits OMC marine engines that originally used part numbers 318973, 321480, or 0777541. Always cross-reference your engine's service manual or original seal dimensions to confirm fit.
Do I need special tools to install this seal?
A seal driver or appropriately sized socket that matches the outer diameter of the seal is recommended to ensure even, square installation without damaging the seal or housing.
What type of oil should I use after installation?
Use the gearcase oil type and viscosity specified in your engine's service manual. Using incorrect oil can affect seal performance and lower unit longevity.
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 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
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