Thermostat – Fits Cummins MerCruiser QSD 2.8L & 4.2L (Replaces 8M0093561, 879194215)
Thermostat – Fits Cummins MerCruiser QSD 2.8L & 4.2L (Replaces 8M0093561, 879194215) 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
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 Cummins MerCruiser QSD 2.8L & 4.2L (Replaces ...
Thermostat – Fits Cummins MerCruiser QSD 2.8L & 4.2L (Replaces 8M0093561, 879194215) is backordered and will ship as soon as it is back in stock.
Product Details
This replacement Thermostat – Fits Cummins MerCruiser QSD 2.8L & 4.2L Diesel Engines, ensuring your marine engine maintains the correct operating temperature for optimal performance and efficiency. It regulates coolant flow by opening at a precise 80°C (176°F) to prevent overheating and maintain stable conditions.
It serves as a direct replacement for Mercury MerCruiser part numbers 8M0093561, 879194215, 879194233, and 39012036F.
- Engineered for marine diesel engine cooling systems.
- Manufactured in an ISO 9002 certified facility to meet OEM specifications.
- Includes one thermostat ready for installation.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Notes |
|---|---|---|
| Mercury MerCruiser | 8M0093561 | Primary replacement |
| Mercury MerCruiser | 879194215 | Interchange |
| Mercury MerCruiser | 879194233 | Interchange |
| Mercury MerCruiser | 39012036F | Interchange |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This part is compatible with the following Cummins MerCruiser Diesel (CMD) engine models.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| MerCruiser | CMD QSD 2.8 EI 170 | 170 | 4-Stroke | 8M0093561 | Diesel engine | |
| MerCruiser | CMD QSD 2.8 EI 210 | 210 | 4-Stroke | 8M0093561 | Diesel engine | |
| MerCruiser | CMD QSD 2.8 EI 220 | 220 | 4-Stroke | 8M0093561 | Diesel engine | |
| MerCruiser | CMD QSD 2.8 EI 230 | 230 | 4-Stroke | 8M0093561 | Diesel engine | |
| MerCruiser | CMD QSD 2.8 ES 170 | 170 | 4-Stroke | 8M0093561 | Diesel engine | |
| MerCruiser | CMD QSD 2.8 ES 210 | 210 | 4-Stroke | 8M0093561 | Diesel engine | |
| MerCruiser | CMD QSD 2.8 ES 220 | 220 | 4-Stroke | 8M0093561 | Diesel engine | |
| MerCruiser | CMD QSD 2.8 ES 230 | 230 | 4-Stroke | 8M0093561 | Diesel engine | |
| MerCruiser | CMD QSD 4.2 EI 270 | 270 | 4-Stroke | 8M0093561 | Diesel engine | |
| MerCruiser | CMD QSD 4.2 EI 320 | 320 | 4-Stroke | 8M0093561 | Diesel engine | |
| MerCruiser | CMD QSD 4.2 EI 350 | 350 | 4-Stroke | 8M0093561 | Diesel engine | |
| MerCruiser | CMD QSD 4.2 ES 270 | 270 | 4-Stroke | 8M0093561 | Diesel engine | |
| MerCruiser | CMD QSD 4.2 ES 320 | 320 | 4-Stroke | 8M0093561 | Diesel engine | |
| MerCruiser | CMD QSD 4.2 ES 350 | 350 | 4-Stroke | 8M0093561 | Diesel engine |
Technical Specs
- Product Type
- Thermostat
- Installation
- Engine cooling system
- Fuel Type
- Diesel
- Opening Temperature
- 80°C (176°F)
- Manufacturing
- Manufactured to OEM specifications in ISO9002 certified factory
What’s in the Box
- 1 x Thermostat (Replaces 8M0093561)
Installation Notes
- Ensure the engine is completely cool before beginning work.
- Drain the engine coolant into a suitable, clean container.
- Locate and remove the thermostat housing. Note the orientation of the old thermostat.
- Remove the old thermostat and thoroughly clean the mating surfaces of the housing and engine.
- Install the new thermostat, ensuring it is in the correct orientation. We highly recommend using a new gasket (not included) to ensure a leak-free seal.
- Re-secure the housing and torque retaining bolts to the manufacturer's specification.
- Refill the cooling system with the correct type and amount of coolant.
- Start the engine, carefully check for any leaks, and monitor the temperature gauge to ensure the thermostat operates correctly.
Troubleshooting & FAQ
How do I know if my engine's thermostat is failing?
Common signs of a faulty thermostat include engine overheating, the temperature gauge reading unusually high or low, poor cabin heater performance, and visible coolant leaks around the thermostat housing.
What temperature does this thermostat open at?
This thermostat is calibrated to begin opening at 80°C (176°F), ensuring your engine reaches and maintains its optimal operating temperature for performance and longevity.
Is a gasket included with this thermostat?
This product includes the thermostat only. Gaskets or O-rings must be purchased separately. Using a new gasket is critical for a proper, leak-proof seal during installation.
Can a bad thermostat cause my engine to run cold?
Yes. If a thermostat fails in the "open" position, it allows coolant to circulate constantly, preventing the engine from warming up to its proper operating temperature. This can lead to increased fuel consumption, higher emissions, and poor performance.
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.
Payment & Security
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