71°C (160°F) Thermostat for Yanmar Marine 2GM20F, 2GMF, 3GM30F, 3GMF, 3GMDF and 3HM Series — OEM 121750-49800
71°C (160°F) Thermostat for Yanmar Marine 2GM20F, 2GMF, 3GM30F, 3GMF, 3GMDF and 3HM Series — OEM 121750-49800 is backordered and will ship as soon as it is back in stock.
Worry-free returns
Worry-free returns
Shop with confidence. If you’re not completely satisfied, eligible items may be returned within the return window, provided they are unused and in original packaging.
If the return is due to our error or a defective item, we’ll make it right.
Please contact us before returning any item.
Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
International delivery times may vary due to customs processing.
Tracking information will be provided once your order ships.
71°C (160°F) Thermostat for Yanmar Marine 2GM20F, 2GMF, 3GM30F, 3GM...
71°C (160°F) Thermostat for Yanmar Marine 2GM20F, 2GMF, 3GM30F, 3GMF, 3GMDF and 3HM Series — OEM 121750-49800 is backordered and will ship as soon as it is back in stock.
Product Details
This 71°C (160°F) replacement thermostat is listed for Yanmar Marine inboard engine models including the 2GMF, 2GM20F, 2GM20F-YEU, 3GMF, 3GMDF, 3GM30F, 3GM30F-YEU, 3HM35F and 3HMF. It is intended to help regulate engine operating temperature by opening at the listed 71°C rating.
The manufacturer reference for this thermostat is Yanmar P/N 121750-49800. Reference number 18-4980 is also listed for identification purposes.
- 71°C (160°F) rated opening temperature.
- Designed for the Yanmar Marine inboard models listed below.
- Single replacement thermostat supplied.
- Verify the engine model and existing part number before ordering.
Part Number References
Use the following numbers when comparing this thermostat with your engine service information or existing part.
| Reference Type | Part Number |
|---|---|
| Yanmar manufacturer reference | 121750-49800 |
| Additional catalog reference | 18-4980 |
Engine & Model Compatibility
The company catalog identifies this thermostat for the following Yanmar Marine inboard engine models. Model suffixes and engine configuration should be matched carefully before purchase.
| Brand | Engine Model | Manufacturer Reference | Rated Opening Temperature |
|---|---|---|---|
| Yanmar Marine Inboard | 2GMF | 121750-49800 | 71°C (160°F) |
| Yanmar Marine Inboard | 2GM20F | 121750-49800 | 71°C (160°F) |
| Yanmar Marine Inboard | 2GM20F-YEU | 121750-49800 | 71°C (160°F) |
| Yanmar Marine Inboard | 3GMF | 121750-49800 | 71°C (160°F) |
| Yanmar Marine Inboard | 3GMDF | 121750-49800 | 71°C (160°F) |
| Yanmar Marine Inboard | 3GM30F | 121750-49800 | 71°C (160°F) |
| Yanmar Marine Inboard | 3GM30F-YEU | 121750-49800 | 71°C (160°F) |
| Yanmar Marine Inboard | 3HM35F | 121750-49800 | 71°C (160°F) |
| Yanmar Marine Inboard | 3HMF | 121750-49800 | 71°C (160°F) |
Technical Specifications
- Product Type
- Thermostat
- Application
- Yanmar Marine inboard engines
- Rated Opening Temperature
- 71°C (160°F)
- Manufacturer Reference
- 121750-49800
- Additional Reference
- 18-4980
- Product Configuration
- Single thermostat
What’s in the Box
- 1 x Thermostat
No gasket, housing, seal or other installation hardware is specified as included. Confirm the required installation components against the engine service manual.
Installation Notes
- Allow the engine to cool completely before beginning work.
- Disconnect the battery and follow the safety procedures in the engine service manual.
- Locate the thermostat housing and remove the cover according to the manufacturer’s instructions.
- Remove the existing thermostat and note its orientation.
- Clean the mating surfaces and inspect the housing, sealing surfaces and related components.
- Install the replacement thermostat in the correct orientation.
- Replace the gasket or seal if required by the service manual; these parts are not specified as included.
- Reassemble the housing, restore the cooling system as applicable and check for leaks.
- Start the engine and confirm normal temperature regulation during a careful test run.
Troubleshooting & FAQ
Which engines is this thermostat listed for?
The company catalog lists Yanmar Marine inboard models 2GMF, 2GM20F, 2GM20F-YEU, 3GMF, 3GMDF, 3GM30F, 3GM30F-YEU, 3HM35F and 3HMF. Match the complete engine model and the existing thermostat reference before ordering.
What temperature does this thermostat open at?
The listed opening temperature is 71°C (160°F).
What part number should I compare?
Compare the existing part with Yanmar reference 121750-49800. The additional catalog reference 18-4980 is also provided for identification.
Does this listing include a complete thermostat kit?
This listing is for one thermostat. A gasket, seal, housing or other installation hardware is not specified as included.
Should I replace the gasket during installation?
Inspect the gasket or seal and replace it when required by the engine service manual. The required gasket or seal is not specified as part of this thermostat package.
What are common signs of thermostat failure?
Possible symptoms include overheating, unusually low operating temperature, slow warm-up or unstable temperature readings. Diagnose the complete cooling system before replacing the thermostat.
How can I confirm fitment?
Check the complete engine model, suffix and existing manufacturer reference against the compatibility table and your service manual. Do not rely on the engine family name alone.
Safety & Important Information
- Allow the engine and cooling system to cool before removing the thermostat housing.
- Follow the engine manufacturer’s service procedures and use appropriate personal protective equipment.
- Verify the model, suffix, temperature rating and part number before purchase.
- Professional installation is recommended when the cooling system or thermostat housing is difficult to access.
About Sea Sierra
- Marine Parts Support — We provide replacement parts for marine engine maintenance and repair.
- Fitment-Focused Listings — Product details are organized around manufacturer references and engine-model compatibility.
- Practical Replacement Solutions — Confirm the application and required installation components before ordering.
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.
