Side Cover Gasket – Fits Yanmar 1GM, 2GM, 3GM Series Engines (Replaces 121575-01861)
Side Cover Gasket – Fits Yanmar 1GM, 2GM, 3GM Series Engines (Replaces 121575-01861) is backordered and will ship as soon as it is back in stock.
Couldn't load pickup availability
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).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Side Cover Gasket – Fits Yanmar 1GM, 2GM, 3GM Series Engines (Repla...
Product Details
This high-quality Side Cover Gasket is engineered to create a perfect seal for the gear housing on compatible Yanmar 1GM, 2GM, 3GM, and 3HM series marine diesel engines. Its precise construction ensures a reliable, leak-free fit, restoring engine integrity and performance.
This part is a direct replacement for Yanmar OEM part number 121575-01861.
- Made from durable, high-grade non-asbestos material for longevity.
- Precision-cut to OEM specifications for a direct fit.
- Seals the gear housing side cover to prevent oil and fluid leaks.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yanmar | 121575-01861 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Stroke | OEM Part No. |
|---|---|---|---|
| Yanmar | 1GM | 4-Stroke | 121575-01861 |
| Yanmar | 1GM10 | 4-Stroke | 121575-01861 |
| Yanmar | 2GM | 4-Stroke | 121575-01861 |
| Yanmar | 2GM(F) | 4-Stroke | 121575-01861 |
| Yanmar | 2GM20 | 4-Stroke | 121575-01861 |
| Yanmar | 2GM20B | 4-Stroke | 121575-01861 |
| Yanmar | 2GM20C | 4-Stroke | 121575-01861 |
| Yanmar | 2GM20F | 4-Stroke | 121575-01861 |
| Yanmar | 2GM20F-YEU | 4-Stroke | 121575-01861 |
| Yanmar | 2GM20FC-YEU | 4-Stroke | 121575-01861 |
| Yanmar | 2GM20VE | 4-Stroke | 121575-01861 |
| Yanmar | 2GMLP | 4-Stroke | 121575-01861 |
| Yanmar | 3GM | 4-Stroke | 121575-01861 |
| Yanmar | 3GM(F) | 4-Stroke | 121575-01861 |
| Yanmar | 3GM30 | 4-Stroke | 121575-01861 |
| Yanmar | 3GM30F | 4-Stroke | 121575-01861 |
| Yanmar | 3GM30F-YEU | 4-Stroke | 121575-01861 |
| Yanmar | 3GM30FC-YEU | 4-Stroke | 121575-01861 |
| Yanmar | 3HM | 4-Stroke | 121575-01861 |
| Yanmar | 3HM35F | 4-Stroke | 121575-01861 |
| Yanmar | 3HMF | 4-Stroke | 121575-01861 |
Technical Specs
- Product Type
- Side Cover Gasket
- Material
- Non-Asbestos
- Dimensions
- 5.5 cm × 5.5 cm × 0.1 cm
- Weight
- Negligible (listed as 0.0 kg)
- Country of Manufacture
- Japan
- Function
- Seals gear housing/side cover
What’s in the Box
- 1 x Gasket, Side Cover (121575-01861)
Installation Notes
- Disconnect the battery and ensure the engine is cool.
- Drain any fluids (e.g., oil) necessary to access the side cover without spillage.
- Carefully remove the bolts securing the side cover and remove the cover.
- Remove the old gasket completely. Use a plastic scraper or appropriate solvent to clean both the engine block and cover surfaces meticulously. Ensure they are free of all old gasket material, oil, and debris.
- Position the new gasket correctly on the engine block.
- Reinstall the side cover and tighten the bolts in a crisscross pattern to the manufacturer's specified torque. Do not over-tighten.
- Refill any drained fluids and check for leaks after starting the engine.
Troubleshooting & FAQ
How do I know if my side cover gasket is failing?
Common signs of a failing gasket include visible oil or coolant leaks around the gear housing, a drop in fluid levels, or engine performance issues. You may also see visible cracks or degradation on the old gasket upon inspection.
Is any sealant required with this gasket?
Typically, this type of gasket is designed for a dry installation. However, always consult your Yanmar service manual for procedures specific to your engine model, as some applications may recommend a thin layer of an appropriate sealant.
What is the most common cause of gasket failure?
Gaskets can fail due to age, extreme heat cycles, improper installation (uneven torque or over-tightening), or damage to the mating surfaces. Using a fresh, high-quality gasket on clean, flat surfaces is critical.
How often should this gasket be replaced?
It is best practice to replace the side cover gasket any time the cover is removed for service, inspection, or repairs. It should also be replaced immediately if a leak is detected.
Will this fit an engine model not in the compatibility list?
We can only guarantee fitment for the Yanmar models explicitly listed. While it may fit other engines, purchasing for an unlisted model is not recommended and would be at your own risk.
OEM vs. Aftermarket Quality?
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 quality and consistency.
What are the shipping speed and cost?
We ship worldwide quickly—typical transit time is 5–15 days. Standard shipping is free to most regions; expedited options and exact costs will appear at checkout where available.
What is the warranty and return policy?
This part is covered by a 1-year warranty against manufacturing defects under normal marine use. If an issue arises, contact our support team with your order details. Returns are accepted within our standard window for items that are unused and in original condition. See our full 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
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
