Cylinder Head Gasket – Fits Yanmar 3GM30 Series Marine Diesel Engines (Replaces 128374-01911)
Cylinder Head Gasket – Fits Yanmar 3GM30 Series Marine Diesel Engines (Replaces 128374-01911) 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
Cylinder Head Gasket – Fits Yanmar 3GM30 Series Marine Diesel Engin...
Product Details
This high-quality Cylinder Head Gasket – Fits Yanmar 3GM30 Series is engineered for 24–27 HP, 3-cylinder, 4-stroke marine diesel engines, including popular models like the 3GM30, 3GM30F, and their variants. It creates a critical, durable seal between the cylinder head and the engine block to prevent combustion gas leaks and coolant or oil intrusion.
This part is a direct cross-reference for Yanmar OEM part 128374-01911 and aftermarket equivalents such as JSK YMAF5077 and YMAF5239.
- Installation: Designed as a drop-in component for engine repair and rebuilds.
- Material: Constructed from high-temperature composite materials to withstand extreme pressures and temperatures.
- Bore Size: Precision-cut for a 75 mm engine bore.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yanmar | 128374-01911 |
| JSK | YMAF5077 |
| JSK | YMAF5239 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This gasket is specifically designed for various Yanmar 3GM30 series marine engines.
| Brand | Model | Rated HP | Stroke | OEM Part No. |
|---|---|---|---|---|
| Yanmar | 3GM30 | 24 | 4-Stroke | 128374-01911 |
| Yanmar | 3GM30-YEU | 24 | 4-Stroke | 128374-01911 |
| Yanmar | 3GM30B | 24 | 4-Stroke | 128374-01911 |
| Yanmar | 3GM30C | 24 | 4-Stroke | 128374-01911 |
| Yanmar | 3GM30C-YEU | 24 | 4-Stroke | 128374-01911 |
| Yanmar | 3GM30F | 27 | 4-Stroke | 128374-01911 |
| Yanmar | 3GM30F-YEU | 27 | 4-Stroke | 128374-01911 |
| Yanmar | 3GM30FC-YEU | 27 | 4-Stroke | 128374-01911 |
| Yanmar | 3GM30FVE | 27 | 4-Stroke | 128374-01911 |
| Yanmar | 3GM30VE | 24 | 4-Stroke | 128374-01911 |
Technical Specs
- Product Type
- Cylinder Head Gasket
- Installation
- Engine repair/rebuild component
- Fuel Type
- Diesel
- Housing Material
- High-temperature composite materials
- Dimensions
- 28.5" L x 14.5" W x 0.2" H
- Bore
- 75 mm
What’s in the Box
- 1 x Cylinder Head Gasket (128374-01911)
Installation Notes
- Disconnect the battery and completely drain the engine's cooling system.
- Remove the exhaust and intake manifolds, valve cover, and any other components blocking access to the cylinder head.
- Loosen and remove the cylinder head bolts in the reverse order of the manufacturer's specified tightening sequence.
- Carefully lift the cylinder head off the engine block. Avoid using pry bars that could gouge the mating surfaces.
- Thoroughly clean both the cylinder head and engine block surfaces, removing all old gasket material, sealant, and residue.
- Place the new head gasket onto the engine block, ensuring correct orientation based on dowel pins and contours. Do not use sealant unless explicitly required by the service manual.
- Carefully lower the cylinder head back into place.
- Lightly oil the threads of the new head bolts and install them finger-tight.
- Using a calibrated torque wrench, tighten the head bolts in multiple stages according to the manufacturer's torque sequence and values.
- Reinstall all previously removed components and reconnect all hoses and electrical connectors.
- Refill the cooling system, reconnect the battery, and check for any leaks before starting the engine.
Troubleshooting & FAQ
How do I know if my head gasket is failing?
Common signs include white smoke from the exhaust (burning coolant), milky or frothy engine oil (coolant contamination), persistent engine overheating, and a noticeable loss of compression or power. A chemical block test or compression test can confirm the diagnosis.
Is this gasket compatible with the 3GM30F engine model?
Yes, this cylinder head gasket is fully compatible with the Yanmar 3GM30F engine and its variants. Please refer to the compatibility table to confirm your specific model.
Do I need to use sealant with this gasket?
No. This is a modern composite gasket designed for dry installation. Applying sealants can interfere with its ability to seal properly and may cause premature failure. Always follow the instructions in your engine's service manual.
What are the signs of an incorrectly installed head gasket?
Immediate signs can include coolant or oil leaks from the head/block seam, rapid overheating, or the same symptoms of head gasket failure returning shortly after repair. Improper torque or a contaminated surface are common causes.
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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