Breather Cover Gasket – Fits Yanmar 2GM, 2GM20, 3GM30F Series (Replaces 121000-03071)
Breather Cover Gasket – Fits Yanmar 2GM, 2GM20, 3GM30F Series (Replaces 121000-03071) 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
Breather Cover Gasket – Fits Yanmar 2GM, 2GM20, 3GM30F Series (Repl...
Product Details
This high-quality Breather Cover Gasket ensures a perfect seal for the engine breather system on various Yanmar marine diesel engines. It is designed to fit 2-cylinder GM series engines (including 2GML, 2GLMP, 2GM20, 2GM20F) and 3-cylinder 3GM30F series, primarily used in applications from the 1980s and 1990s.
This part serves as a direct replacement for Yanmar OEM part number 121000-03071, ensuring reliable performance and compatibility.
- Prevents oil leakage by sealing the breather cover assembly.
- Designed for use in diesel marine engine environments.
- Installs directly into the engine's breather system.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yanmar | 121000-03071 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This gasket is compatible with the following Yanmar Marine diesel engines.
| Brand | Model | Rated HP | Stroke | OEM Part No. |
|---|---|---|---|---|
| Yanmar | 2GML | 4-Stroke | 121000-03071 | |
| Yanmar | 2GLMP | 4-Stroke | 121000-03071 | |
| Yanmar | 2GM20 | 20 | 4-Stroke | 121000-03071 |
| Yanmar | 2GM20F | 20 | 4-Stroke | 121000-03071 |
| Yanmar | 2GM20F-YEU | 20 | 4-Stroke | 121000-03071 |
| Yanmar | 2GM20-YEU | 20 | 4-Stroke | 121000-03071 |
| Yanmar | 2GMLP | 4-Stroke | 121000-03071 | |
| Yanmar | 3GM30F | 30 | 4-Stroke | 121000-03071 |
| Yanmar | 3GM30F-YEU | 30 | 4-Stroke | 121000-03071 |
Technical Specs
- Product Type
- Breather Cover Gasket
- Installation
- Engine Breather System
- Fuel Type
- Diesel
- Housing Material
- Paper/Composite
- Dimensions
- 6.5 cm × 4.5 cm × 0.2 cm (W × L × H)
- Weight
- Approximately 0.01 kg
- Function
- Seals the breather cover assembly to prevent oil leakage.
What’s in the Box
- 1 × Breather Cover Gasket (Replaces 121000-03071)
Installation Notes
- Ensure the engine is off and cool. Disconnect the battery for safety.
- Remove the old breather cover and gasket. Note the orientation and position of all components.
- Thoroughly clean both mating surfaces on the engine block and the breather cover. Remove all old gasket material and residue.
- Align the new gasket onto the engine block. Ensure all bolt holes line up correctly.
- Carefully place the breather cover over the new gasket.
- Hand-tighten the bolts in an alternating pattern to seat the cover evenly.
- Torque the bolts to the manufacturer's specified values using a torque wrench. Do not overtighten.
- Reconnect the battery, start the engine, and check for any oil leaks around the breather cover.
Troubleshooting & FAQ
How do I know if this gasket will fit my Yanmar engine?
This gasket is designed for Yanmar's 2GM and 3GM series engines. Please review the 'Engine & Model Compatibility' table on this page and cross-reference the OEM part number (121000-03071) with your engine's service manual to ensure an exact match.
What are the signs of a failing breather cover gasket?
Common signs of a worn or failed gasket include visible oil leaks or seepage around the breather cover, a smell of burning oil, or a dirty, grimy engine bay in that specific area. This can lead to low oil levels and poor engine performance if not addressed.
Is any sealant needed when installing this gasket?
Generally, this type of paper/composite gasket is designed to be installed dry. Applying sealant is not usually recommended unless explicitly stated in your engine's service manual, as it can sometimes interfere with a proper seal.
How often should gaskets like this be replaced?
There is no fixed replacement interval. Gaskets should be replaced whenever the component they seal is removed for service, or immediately if you notice any signs of leakage or damage.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. Our parts are manufactured in an ISO 9002 facility and are batch-inspected for consistency and quality.
Shipping speed & cost
We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free; expedited options will appear at checkout where available.
Warranty & returns
This product is covered by a 1-year warranty against manufacturing defects under normal use. If any issues arise, please contact our support team with your order details. Returns are accepted within our standard window for unused items in their original condition. See our policy page or reach out for instructions.
Safety & Important Info
- Verify images and specifications against your original part before purchase. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement part, not an OEM component.
- Professional installation is highly recommended for safety and optimal performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world conditions.
- Fast Global Fulfillment — We offer free standard delivery to most regions, with typical transit times of 5–15 days.
- Manufacturer-Direct Value — By working directly with manufacturers, we provide fair pricing without compromising on materials or quality control.
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