Thermostat Gasket – Fits Yanmar 6LY3 Series (Replaces 119578-49110)
Thermostat Gasket – Fits Yanmar 6LY3 Series (Replaces 119578-49110) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Thermostat Gasket – Fits Yanmar 6LY3 Series (Replaces 119578-49110)
Product Details
This is a direct replacement Thermostat Gasket – Fits Yanmar 6LY3 Series, designed for consistent performance in marine environments. It is engineered for Yanmar 6LY3 series diesel engines from 2000 to the present, ensuring a reliable, leak-proof seal for the thermostat housing.
This part is a direct replacement for Yanmar part number 119578-49110 and aftermarket equivalent REC119578-49110.
- Installation Method: Direct replacement
- Environment: Designed for marine diesel cooling systems
- Included in Package: One thermostat gasket
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Notes |
|---|---|---|
| Yanmar | 119578-49110 | Original Equipment Manufacturer |
| Aftermarket | REC119578-49110 | Direct Replacement |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This gasket is used on the fresh water cooling pump for the following Yanmar engines.
| Brand | Model | Stroke | OEM Part No. | Notes |
|---|---|---|---|---|
| Yanmar | 6LY3-ETP | 4-Stroke | 119578-49110 | Used on cooling pump (fresh water) |
| Yanmar | 6LY3-ETP 24 | 4-Stroke | 119578-49110 | Used on cooling pump (fresh water) |
| Yanmar | 6LY3-STC | 4-Stroke | 119578-49110 | Used on cooling pump (fresh water) |
| Yanmar | 6LY3-STC 24 | 4-Stroke | 119578-49110 | Used on cooling pump (fresh water) |
| Yanmar | 6LY3-STP | 4-Stroke | 119578-49110 | Used on cooling pump (fresh water) |
| Yanmar | 6LY3-STP 24 | 4-Stroke | 119578-49110 | Used on cooling pump (fresh water) |
| Yanmar | 6LY3-UTC | 4-Stroke | 119578-49110 | Used on cooling pump (fresh water) |
| Yanmar | 6LY3-UTC 24 | 4-Stroke | 119578-49110 | Used on cooling pump (fresh water) |
| Yanmar | 6LY3-UTP | 4-Stroke | 119578-49110 | Used on cooling pump (fresh water) |
| Yanmar | 6LY3-UTP 24 | 4-Stroke | 119578-49110 | Used on cooling pump (fresh water) |
Technical Specs
- Product Type
- Thermostat Gasket
- Installation
- Direct replacement
- Fuel Type
- Diesel
- Housing Material
- High temperature resistant material
- Dimensions
- 8.5" x 8.5" x 0.5"
- Operating Temperature
- High-temperature resistant (designed for marine diesel cooling systems)
- Other Technical Attributes
- Ensures leak-proof seal for thermostat housing
What’s in the Box
- 1 x Thermostat Gasket (Replaces 119578-49110)
Installation Notes
- Ensure the engine is cool and disconnect the battery terminals.
- Drain the coolant from the system to a level below the thermostat housing.
- Carefully remove the bolts securing the thermostat housing and lift the housing away.
- Remove the old thermostat gasket. Thoroughly clean both the engine and housing mating surfaces to remove any old debris or sealant.
- Position the new gasket correctly onto the engine block or thermostat housing recess.
- Reinstall the thermostat housing and tighten the bolts in a cross pattern to the manufacturer-specified torque.
- Refill the cooling system with the appropriate coolant.
- Reconnect the battery, start the engine, and carefully inspect for any leaks around the housing as it comes up to temperature.
Troubleshooting & FAQ
How do I confirm this gasket fits my Yanmar 6LY3 engine?
Please check the "Engine & Model Compatibility" table on this page. It lists all confirmed models like the 6LY3-ETP, 6LY3-STC, and 6LY3-UTC. We also recommend visually comparing the gasket shape in our photos with your old part before ordering to ensure a perfect match.
What are the signs of a failing thermostat gasket?
Telltale signs include visible coolant leaks or weeping around the thermostat housing, engine overheating issues caused by coolant loss, or discovering that the old gasket is cracked, brittle, or compressed during inspection.
Should I use sealant or adhesive with this gasket?
This gasket is designed to create a reliable seal on its own. In general, no additional sealant is needed. The key is to ensure both mounting surfaces are perfectly clean and free of any old gasket material or corrosion before installation.
When should I replace my thermostat gasket?
It is best practice to replace the thermostat gasket every time the thermostat itself is serviced or replaced. This ensures a fresh, dependable seal and prevents the risk of leaks developing from reusing an old, compressed gasket.
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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