GASKET – Fits Johnson/Evinrude 15hp (Replaces OMC 308328)
GASKET – Fits Johnson/Evinrude 15hp (Replaces OMC 308328) 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
GASKET – Fits Johnson/Evinrude 15hp (Replaces OMC 308328)
Product Details
This is a replacement GASKET – Fits Johnson/Evinrude 15hp (Replaces OMC 308328), specifically a thermostat cover gasket designed for Johnson/Evinrude 15hp, 2-Stroke engines from 1971. It ensures a proper seal for the thermostat housing to prevent coolant leaks.
This part is a direct replacement for OEM part number OMC 308328 and aftermarket equivalent GLM 33290.
- Product Type: Thermostat Cover Gasket
- Shape: Round
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| OMC | 308328 |
| OMC | 0308328 |
| GLM | 33290 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This gasket is confirmed for the following Johnson and Evinrude models. Verify your part number, as variations exist.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Johnson | 15hp | 15 | 2-Stroke | 1971 | 308328 | |
| Evinrude | 25253R | 25 | 1972 | 308328 | Fits Cylinder & Crankcase |
Technical Specs
- Product Type
- Thermostat Cover Gasket
- Dimensions
- 11.5 x 9.0 x 0.3 inches
- Weight
- 0.45 kg (1 pound)
- Shape
- Round
What’s in the Box
- Gasket, Cap (0308328)
Installation Notes
- Disconnect the battery before starting work.
- Drain the engine coolant to a level below the thermostat housing.
- Carefully remove the bolts that secure the thermostat housing cover.
- Remove the old cover and gasket. Thoroughly clean all mating surfaces to remove old gasket material and any corrosion.
- Position the new gasket onto the housing surface, ensuring correct alignment.
- Reinstall the thermostat cover and tighten the bolts to the manufacturer's specified torque in a crisscross pattern.
- Refill the cooling system with the appropriate coolant.
- Reconnect the battery, start the engine, and carefully check for any leaks around the housing as the engine warms up.
Troubleshooting & FAQ
How do I know if this gasket fits my engine?
This gasket is designed for the Johnson/Evinrude 15hp 2-Stroke engine from 1971 and other models listed. Always check the Part Number Matrix and Engine Compatibility table on this page against your engine's model, year, and original part number (308328). Visual comparison with your old part is also recommended.
What is the main sign of a failed thermostat gasket?
The most common symptom is a visible coolant leak from around the seam of the thermostat housing. This can lead to engine overheating if the coolant level drops significantly, so it should be addressed promptly.
Is sealant required with this gasket?
Generally, new gaskets are designed to seal without additional sealant. However, if the housing surfaces are slightly pitted or uneven from age, a thin, even application of a marine-grade gasket sealant can help ensure a perfect seal. Always consult your engine's service manual for specific recommendations.
How often should this gasket be replaced?
It is best practice to replace the thermostat gasket whenever the thermostat itself is serviced or replaced. You should also replace it immediately if you detect a leak.
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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