Thermostat – Fits Mercury Marine 75-175 HP DFI Outboard Motors (Replaces 833072003)
Thermostat – Fits Mercury Marine 75-175 HP DFI Outboard Motors (Replaces 833072003) is backordered and will ship as soon as it is back in stock.
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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.
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Thermostat – Fits Mercury Marine 75-175 HP DFI Outboard Motors (Rep...
Thermostat – Fits Mercury Marine 75-175 HP DFI Outboard Motors (Replaces 833072003) is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket Thermostat – Fits Mercury Marine 75-175 HP DFI Outboard Motors (Replaces 833072003) is engineered to regulate engine temperature for select Mercury Marine and Optimax 1.5L and 2.5L DFI 2-stroke outboard motors from 1998 onwards. It ensures the engine maintains its proper operating temperature for optimal performance, fuel efficiency, and longevity.
It serves as a direct interchange for Mercury part numbers 833072, 833072002, 833072003, 833072004, and Sierra 18-3536.
- Engineered for direct replacement installation.
- Constructed from marine-grade metal with a durable rubber seal.
- Maintains a factory-specified operating temperature of 143°F (61.6°C).
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury | 833072 |
| Mercury | 833072002 |
| Mercury | 833072003 |
| Mercury | 833072004 |
| Sierra | 18-3536 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury engines, it is critical to verify compatibility using your engine's serial number range, as fitment can vary within the same model year. The ranges provided below are specific to this part.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | 1.5L 3-Cyl DFI | 75 | 2-Stroke | 2006+ (0T980000-Up) | 833072003 | |
| Mercury | 1.5L 3-Cyl DFI | 90 | 2-Stroke | 2004+ (0T801000-Up) | 833072003 | |
| Mercury | 1.5L 3-Cyl DFI | 115 | 2-Stroke | 2004+ (0T801000-Up) | 833072003 | |
| Mercury | 2.5L V135 DFI | 135 | 2-Stroke | 1998+ (0G590000-Up) | 833072003 | |
| Mercury | 2.5L V150 DFI | 150 | 2-Stroke | 1998+ (0G590000-Up) | 833072003 | |
| Mercury | 2.5L V175 DFI | 175 | 2-Stroke | 2001+ (0T178500-Up) | 833072003 | |
| Mercury | Optimax | 135-200 | 2-Stroke | 1998+ | 833072003 | Models not specified |
Technical Specs
- Product Type
- Engine Thermostat
- Installation
- Direct Replacement
- Housing Color
- Silver/Metallic
- Operating Temperature
- 143°F (61.6°C)
- Materials
- Marine Grade Metal with Rubber Seal
- Other Technical Attributes
- Requires thermostat seal 27-887978/8M0204714 (included with some packages)
What’s in the Box
- 1 x Thermostat (Replaces 833072003)
- 2 x Thermostat Seals (Replaces 8M0204714)
Note: Package contents may vary by seller. Verify contents before purchase to ensure seals are included if needed.
Installation Notes
- Ensure the engine is completely cool and disconnect the battery for safety.
- Drain the engine coolant into a suitable container.
- Locate the thermostat housing on the engine block or cylinder head.
- Remove the bolts securing the housing cover and carefully lift it off. Note the orientation of the old thermostat.
- Remove the old thermostat and its seal. Clean both mating surfaces of the housing and cover thoroughly.
- Install the new thermostat seal and place the new thermostat in the housing, ensuring it is correctly oriented.
- Re-secure the housing cover and tighten bolts to the manufacturer's specified torque.
- Refill the cooling system with the recommended coolant, and check for any leaks.
- Reconnect the battery. Start the engine and allow it to reach operating temperature, monitoring for proper function and any signs of leaks.
Troubleshooting & FAQ
How do I know if this thermostat fits my engine?
The best way is to check your current part number against the "Part Number Matrix" provided. Additionally, review the "Engine & Model Compatibility" table, paying close attention to your engine's model, horsepower, and serial number range. When in doubt, compare our product photos to your existing part.
Do I need to replace the thermostat seal at the same time?
Yes, it is highly recommended to replace the thermostat seal (gasket) whenever you replace the thermostat. This ensures a proper, leak-free seal. Some packages include the required seals; please verify before purchasing.
What are the signs of a failing thermostat?
A thermostat can fail in two ways: stuck open or stuck closed. If it's stuck open, your engine will take a very long time to warm up or may never reach its proper operating temperature, leading to poor performance and fuel economy. If it's stuck closed, the engine will overheat quickly, which can cause severe damage.
How often should I replace my outboard's thermostat?
Replacement intervals vary based on usage and operating conditions (especially in saltwater). As a general maintenance guideline, many technicians recommend inspecting or replacing the thermostat every 2-3 years or 200-300 hours to prevent overheating issues.
What is the difference between this and an OEM part?
This is an aftermarket replacement part, not an original equipment manufacturer (OEM) component. It is designed to meet or exceed OEM specifications for fit, form, and function, offering a high-quality, cost-effective alternative. It is manufactured in an ISO 9002 certified facility and is batch-inspected for quality control.
How fast is shipping?
We ship worldwide, with most orders arriving within 5 to 15 business days via standard shipping. Expedited shipping options are available at checkout for most regions if you need the part sooner.
What is the warranty and return policy?
This product is covered by a 1-year warranty against manufacturing defects under normal use. If you encounter an issue, please contact our support team with your order number. We accept returns for unused items in their original condition within our standard return window. Please see our full policy page or contact us for instructions.
Safety & Important Info
- Verify images and specifications against 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 quality control.
Payment & Security
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