Water Pump Gasket – Fits OMC/Johnson/Evinrude 75-300 HP (Replaces 338484)
Water Pump Gasket – Fits OMC/Johnson/Evinrude 75-300 HP (Replaces 338484) 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).
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Water Pump Gasket – Fits OMC/Johnson/Evinrude 75-300 HP (Replaces 3...
Product Details
This Water Pump Gasket is a direct replacement part designed for a wide range of Johnson and Evinrude outboard engines, specifically V4, V6, and V8 models from 75 to 300 HP manufactured between 1980 and 2011. It ensures a proper seal between the water pump and the plate, preventing leaks and maintaining cooling system integrity.
It serves as a direct interchange for several part numbers, including OMC 338484, Sierra 18-2557, SEI Marine 602-95-306-02, and Aqua Power 338484.
- Installation: Mounts between the water pump housing and the wear plate.
- Material: Constructed from a durable paper/composite blend to withstand the marine environment.
- Engine Type: Designed for gasoline outboard engines.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket brands.
| Brand | Part Number |
|---|---|
| OMC | 338484 |
| Sierra | 18-2557 |
| SEI Marine | 602-95-306-02 |
| Aqua Power | 338484 |
Engine & Model Compatibility
Confirm your engine model and year in the table below.
Johnson/Evinrude Applications: This gasket fits a broad range of V4, V6, and V8 two-stroke engines from 1980 through 2011. Please verify your specific model against the OEM part number.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Johnson/Evinrude | V4, V6, V8 | 75-300 | 2-Stroke | 1980–2011 | 338484 | Water pump plate gasket |
Technical Specs
- Product Type
- Water Pump Gasket
- Installation
- Between water pump and plate
- Fuel Type
- Gasoline
- Material
- Paper/Composite
- Dimensions
- 6.0" x 7.13" x 0.19"
- Weight
- 0.16 ounces (4.5 g)
- Warranty
- 30-day return (varies by retailer)
What’s in the Box
- 1 x Water Pump Gasket (338484)
Installation Notes
- Disconnect the battery and ensure the engine is off and cool.
- Remove the lower unit (gearcase) from the outboard's midsection.
- Unbolt and remove the water pump housing to access the old gasket and impeller.
- Carefully remove the old plate gasket, ensuring the mating surfaces are completely clean of any old material or sealant.
- Position the new gasket (338484) correctly onto the lower unit plate.
- Reinstall the water pump housing, impeller, and keyway, tightening bolts to the manufacturer's recommended torque specifications.
- Reattach the lower unit to the engine.
- Reconnect the battery and test the engine using a water supply (flushing muffs) to check for proper water flow and no leaks.
Troubleshooting & FAQ
How do I know if my water pump gasket is failing?
Signs of a failing water pump gasket include visible water leaks around the pump housing, engine overheating at idle or low speeds, and a weak or inconsistent stream from the tell-tale outlet. Disassembly and inspection may reveal a torn, brittle, or compressed gasket.
Can I reuse my old gasket if it looks okay?
No. Gaskets are single-use components designed to crush and seal. Once compressed, they will not provide a reliable seal if reused. Always replace the gasket whenever servicing the water pump.
Is sealant required with this gasket?
Generally, this type of gasket is installed dry. Applying sealant can sometimes cause the gasket to slip out of place during assembly. Always consult your engine's specific service manual, but in most cases, a clean, dry installation is recommended.
How often should the water pump assembly, including this gasket, be replaced?
As a general rule, the entire water pump impeller and gasket kit should be replaced every 1-2 years or every 100-200 hours of use, whichever comes first. This is critical preventative maintenance to avoid overheating.
Does this gasket fit both saltwater and freshwater models?
Yes, the composite material is designed to hold up in both saltwater and freshwater environments. The key is ensuring it fits your specific engine model and year.
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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