Description
Thermostat Kit (122°F/50°C)Fits Tohatsu/Nissan 250 HP (Replaces 345-01030-0, 346-01030-0)
This thermostat kit is designed to fit a wide range of Tohatsu and Nissan 250 HP, 2-Stroke & 4-Stroke outboard engines from various models manufactured between 20012014, including the MFS, MF, M, and MD series.
It serves as a direct replacement for Tohatsu part numbers: 345-01030-0, 345010300M, 345010301M, 346-01030-0, 346-01030-1, 350-01030-1, and 3H6-01030-0.
- Complete kit includes the thermostat, housing gasket, and seals for a full replacement.
- Engineered for a direct OEM replacement fit and function.
- Maintains engine temperature with a specified opening rating of 122°F (50°C).
Part Number Cross-Reference
Use this table to confirm equivalent part numbers across OEM and aftermarket brands.
| Brand | Part Number |
|---|---|
| Tohatsu | 345-01030-0 |
| Tohatsu | 345010300M |
| Tohatsu | 345010301M |
| Tohatsu | 346-01030-0 |
| Tohatsu | 346-01030-1 |
| Tohatsu | 350-01030-1 |
| Tohatsu | 3H6-01030-0 |
Compatible Engine Models
Confirm your engine model/year in the table below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. |
|---|---|---|---|---|---|
| Tohatsu | MFS2 | 2 | 4-Stroke | 345-01030-0 | |
| Tohatsu | MFS2.5 | 2.5 | 4-Stroke | 345-01030-0 | |
| Tohatsu | MFS3.5C | 3.5 | 4-Stroke | 345-01030-0 | |
| Tohatsu | MFS5 | 5 | 4-Stroke | 345-01030-0 | |
| Tohatsu | MF6 | 6 | 4-Stroke | 2006 | 345-01030-0 |
| Tohatsu | M8B | 8 | 2-Stroke | 345-01030-0 | |
| Tohatsu | M9.8B | 9.8 | 2-Stroke | 345-01030-0 | |
| Tohatsu | M9.9D2 | 9.9 | 2-Stroke | 345-01030-0 | |
| Tohatsu | M15D2 | 15 | 2-Stroke | 345-01030-0 | |
| Tohatsu | M18E2 | 18 | 2-Stroke | 345-01030-0 | |
| Tohatsu | M25C3 | 25 | 2-Stroke | 2003 | 345-01030-0 |
| Tohatsu | M30A4 | 30 | 2-Stroke | 2003 | 345-01030-0 |
| Tohatsu | M40C | 40 | 2-Stroke | 2004 | 345-01030-0 |
| Tohatsu | MD40A, MD40B, MD40B2 | 40 | 4-Stroke TLDI | 2010-2014 | 345010300M |
| Tohatsu | MD50A, MD50B, MD50B2 | 50 | 4-Stroke TLDI | 2010-2014 | 345010300M |
| Nissan | NS25C3 | 25 | 2-Stroke | 2003 | 345-01030-0 |
| Nissan | NS30A4 | 30 | 2-Stroke | 2003 | 345-01030-0 |
| Nissan | NS40C | 40 | 2-Stroke | 2004 | 345-01030-0 |
| Nissan | NSD40B, NSD40B2 | 40 | 4-Stroke TLDI | 2010-2014 | 345010300M |
| Nissan | NSD50B, NSD50B2 | 50 | 4-Stroke TLDI | 2010-2014 | 345010300M |
Technical Specifications
| Specification | Value |
|---|---|
| Product Type | Thermostat with Gasket and Seals |
| Installation | Direct OEM replacement |
| Temperature Rating | 122°F (50°C) |
| Housing Material | Metal |
| Housing Color | Silver/Metallic |
| Operating Temperature | 122°F (50°C) opening temperature |
Package Contents
- 1 x Thermostat (346-01030-0/345-01030-0)
- 1 x Thermostat Housing Gasket
- 2 x Thermostat Seals
Installation Guide
- Ensure the engine is cool and disconnect the battery.
- Drain the engine coolant to a level below the thermostat housing.
- Locate and unbolt the thermostat housing cover.
- Carefully remove the old thermostat and its gasket/seals.
- Thoroughly clean the mating surfaces of the housing and cover.
- Install the new thermostat, ensuring it is correctly oriented.
- Position the new gasket and seals correctly on the housing.
- Reinstall the housing cover and tighten the bolts to the manufacturer’s specified torque.
- Reconnect all hoses and refill the cooling system.
- Reconnect the battery, start the engine, and carefully check for any leaks as it warms up.
Troubleshooting & FAQ
How do I confirm this thermostat kit fits my Tohatsu or Nissan engine?
Check your engine’s model, horsepower, and year against the “Compatible Engine Models” table. You can also verify by matching your existing part number with those listed in the “Part Number Cross-Reference” section.
What are the signs that my outboard’s thermostat is failing?
Common signs include engine overheating, running too cold and failing to reach proper operating temperature, or erratic temperature gauge readings. A faulty thermostat can lead to poor performance, increased fuel consumption, and engine damage.
What is the operating temperature of this thermostat?
This thermostat is designed to begin opening at 122°F (50°C) to regulate the engine’s operating temperature for optimal performance.
OEM vs. Aftermarket?
This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.
How fast do you ship and how much does it cost?
We offer fast global shippingtypically 515 days worldwideand standard shipping is free. Expedited options are available at checkout depending on your location.
What is your warranty and return policy?
This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.
Important Notes
- Verify that the product images and specifications match your original part. If discrepancies existeven if your model is listeddo not proceed with the purchase.
- This product is an aftermarket replacement part and is not an OEM component.
- Professional installation is recommended to ensure safety and optimal performance.
Why Choose JLM MARINE?
- Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
- Fast Global Shipping: Free delivery worldwide in 515 days.
- Direct from Manufacturer: Competitive pricing without compromising quality.
