Rocker Cover Gasket – Fits Yanmar 3GM Series Marine Diesel Engines (Replaces 121450-11310)
Rocker Cover Gasket – Fits Yanmar 3GM Series Marine Diesel Engines (Replaces 121450-11310) is backordered and will ship as soon as it is back in stock.
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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.).
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Rocker Cover Gasket – Fits Yanmar 3GM Series Marine Diesel Engines ...
Product Details
This aftermarket Rocker Cover Gasket is designed for a precise fit on Yanmar 3GM series marine diesel engines, including models 3GM, 3GM30, 3GM30F, 3GM30-YEU, and 3GMF. It provides a reliable seal for the valve cover, preventing oil leaks and ensuring engine integrity.
This part is a direct replacement for Yanmar OEM part number 121450-11310.
- Designed for a direct, hassle-free installation.
- Engineered to withstand heat and oil in a marine diesel environment.
- Essential for maintaining a tight seal between the valve cover and engine block.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yanmar | 121450-11310 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This gasket is designed for specific Yanmar 3GM-series marine engines. Please verify your model is listed before ordering.
| Brand | Model | Stroke | OEM Part No. | Notes |
|---|---|---|---|---|
| Yanmar | 3GM | 4-Stroke | 121450-11310 | |
| Yanmar | 3GM30 | 4-Stroke | 121450-11310 | |
| Yanmar | 3GM30F | 4-Stroke | 121450-11310 | |
| Yanmar | 3GM30-YEU | 4-Stroke | 121450-11310 | |
| Yanmar | 3GMF | 4-Stroke | 121450-11310 | |
| Yanmar | 30D | 4-Stroke | 121450-11310 | Referenced in source 1 |
Technical Specs
- Product Type
- Rocker Cover Gasket
- Installation
- Direct replacement
- Fuel Type
- Diesel
- Material
- Heat and oil-resistant rubber/composite
- Dimensions
- 5.0" L x 5.0" W x 0.1" H
- Operating Temperature
- Heat-resistant for engine valve cover application
- Other Technical Attributes
- Essential for maintaining a tight seal between valve cover and engine block
What’s in the Box
- 1 x Rocker Cover Gasket (121450-11310)
Installation Notes
- Ensure the engine is cool and the battery is disconnected before starting.
- Clean the valve cover and cylinder head mating surfaces thoroughly. Remove all old gasket material, oil, and debris.
- Inspect both mating surfaces for warping, cracks, or deep scratches that could prevent a proper seal.
- Carefully press the new gasket into the groove on the rocker cover, ensuring it is seated evenly.
- Position the rocker cover onto the cylinder head, aligning all bolt holes.
- Hand-tighten the bolts, then tighten them to the manufacturer's specified torque in the recommended sequence to ensure even pressure and prevent leaks.
Troubleshooting & FAQ
How do I know if my rocker cover gasket needs replacing?
Common signs include visible oil leaks around the valve cover, a burning oil smell from the engine bay, or a dirty, oil-soaked area on top of the engine near the gasket seam.
Will this fit any Yanmar engine?
No. This gasket is specifically designed for the Yanmar 3GM series, including models 3GM, 3GM30, 3GM30F, 3GM30-YEU, and 3GMF. Always verify your engine model is listed in the compatibility table before purchasing.
Does this gasket require any sealant or adhesive?
Generally, modern gaskets like this one are designed to be installed dry. However, always consult your engine's service manual for specific procedures, as a small dab of RTV sealant at sharp corners or joints may sometimes be recommended.
What causes a new rocker cover gasket to leak?
A new gasket can fail if the mating surfaces weren't perfectly clean, if the cover or head surface is warped, or if the cover bolts were not tightened to the correct torque or in the proper sequence.
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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