Thermostat (160°F/71°C) – Fits MerCruiser 3.0L-7.4L V6/V8 (Replaces 8072522, 807252T2, 8M0109441)
Thermostat (160°F/71°C) – Fits MerCruiser 3.0L-7.4L V6/V8 (Replaces 8072522, 807252T2, 8M0109441) is backordered and will ship as soon as it is back in stock.
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Thermostat (160°F/71°C) – Fits MerCruiser 3.0L-7.4L V6/V8 (Replaces...
Product Details
This Sierra 18-3649 marine Thermostat (160°F/71°C) – Fits MerCruiser 3.0L-7.4L V6/V8 is engineered for a wide range of MerCruiser 3.0L to 7.4L GM EFI and carbureted engines from 1987 and newer. It is designed for models with either Alpha or Bravo sterndrives that utilize a fresh water (closed) cooling system requiring a 160°F thermostat.
It serves as a direct replacement for MerCruiser, Crusader, GLM, and Mallory part numbers, ensuring broad cross-reference compatibility.
- Designed for fresh water (closed) cooling systems only.
- Regulates engine operating temperature to 160°F (71°C).
- Internal installation within the engine's cooling system housing.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket brands.
| Brand | Part Number |
|---|---|
| MerCruiser | 8052732 |
| MerCruiser | 8072522 |
| MerCruiser | 807252T2 |
| MerCruiser | 8M0091470 |
| MerCruiser | 8M0109441 |
| Crusader | 97895 |
| GLM | 13100 |
| GLM | 13101 |
| Mallory | 9-43002 |
| Mallory | 9-43157 |
| Sierra | 18-3649 |
Engine & Model Compatibility
Confirm your engine model and year in the table below.
For MerCruiser models, this thermostat fits a wide range of V6 and V8 engines from 1987 and newer equipped with fresh water cooling systems.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| MerCruiser | 3.0L GM | Various | 4-Stroke | 1987 and newer | 8052732, 8072522, 807252T2, 8M0091470 | Requires 160° thermostat |
| MerCruiser | 3.0L MPI EC | Various | 4-Stroke | 1987 and newer | 8052732, 8072522, 807252T2, 8M0091470 | Requires 160° thermostat |
| MerCruiser | 4.3L GM 262 V6 | Various | 4-Stroke | 1987 and newer | 8052732, 8072522, 807252T2, 8M0091470 | Requires 160° thermostat |
| MerCruiser | 4.3L Carb Alpha/Bravo | Various | 4-Stroke | 1987 and newer | 8052732, 8072522, 807252T2, 8M0091470 | Requires 160° thermostat |
| MerCruiser | 4.3L EFI TBI GM 262 V6 | Various | 4-Stroke | 1987 and newer | 8052732, 8072522, 807252T2, 8M0091470 | Requires 160° thermostat |
| MerCruiser | 4.3L MPI Alpha/Bravo | Various | 4-Stroke | 1987 and newer | 8052732, 8072522, 807252T2, 8M0091470 | Requires 160° thermostat |
| MerCruiser | 4.3LH GM 262 V6 | Various | 4-Stroke | 1987 and newer | 8052732, 8072522, 807252T2, 8M0091470 | Requires 160° thermostat |
| MerCruiser | 5.0L GM 305 V8 | Various | 4-Stroke | 1987 and newer | 8052732, 8072522, 807252T2, 8M0091470 | Requires 160° thermostat |
| MerCruiser | 5.0L Carb Alpha/Bravo | Various | 4-Stroke | 1987 and newer | 8052732, 8072522, 807252T2, 8M0091470 | Requires 160° thermostat |
| MerCruiser | 5.0L EFI GM 305 V8 | Various | 4-Stroke | 1987 and newer | 8052732, 8072522, 807252T2, 8M0091470 | Requires 160° thermostat |
| MerCruiser | 5.0L MPI Alpha/Bravo | Various | 4-Stroke | 1987 and newer | 8052732, 8072522, 807252T2, 8M0091470 | Requires 160° thermostat |
| MerCruiser | 5.7L GM 350 V8 | Various | 4-Stroke | 1987 and newer | 8052732, 8072522, 807252T2, 8M0091470 | Requires 160° thermostat |
| MerCruiser | 5.7L Carb Alpha/Bravo | Various | 4-Stroke | 1987 and newer | 8052732, 8072522, 807252T2, 8M0091470 | Requires 160° thermostat |
| MerCruiser | 5.7L EFI GM 350 V8 | Various | 4-Stroke | 1987 and newer | 8052732, 8072522, 807252T2, 8M0091470 | Requires 160° thermostat |
| MerCruiser | MX 6.2L MPI Bravo | Various | 4-Stroke | 1987 and newer | 8052732, 8072522, 807252T2, 8M0091470 | Requires 160° thermostat |
| MerCruiser | MX 6.2L MPI Horizon Bravo | Various | 4-Stroke | 1987 and newer | 8052732, 8072522, 807252T2, 8M0091470 | Requires 160° thermostat |
| MerCruiser | 7.4L Bravo GM 454 V8 | Various | 4-Stroke | 1987 and newer | 8052732, 8072522, 807252T2, 8M0091470 | Requires 160° thermostat |
| Crusader | Various GM-based engines | Various | 4-Stroke | 97895 | Requires 160° thermostat |
Technical Specs
- Product Type
- Marine Engine Thermostat
- Installation
- Internal, Engine Cooling System
- Temperature Rating
- 160°F (71°C)
- Cooling System Type
- Fresh Water Cooling (Closed Cooling)
- Housing Material
- Metal (Stainless Steel)
- Weight
- 0.05 kg (0.12 lb)
- Operating Temperature
- 160°F (71°C) opening temperature
- Warranty
- 1 Year Limited (Sierra)
- Other Technical Attributes
- For fresh water cooling systems only
What’s in the Box
- 1 x Thermostat (Replaces 8M0109441)
Installation Notes
- Ensure the engine is completely cool before starting.
- Drain the coolant from the engine block into a suitable container.
- Locate the thermostat housing, typically on top of the engine where the main coolant hose connects.
- Remove the bolts securing the housing cover. Note the orientation of the housing.
- Lift the cover and remove the old thermostat. Take note of its orientation.
- Clean both the housing and cover mating surfaces thoroughly, removing all old gasket material.
- Install the new thermostat in the correct orientation.
- Place a new gasket on the housing and reinstall the cover, tightening bolts to the manufacturer's specified torque.
- Refill the cooling system with the appropriate coolant.
- Start the engine and check for leaks around the housing. Allow the engine to reach operating temperature to ensure the thermostat opens correctly.
Troubleshooting & FAQ
How do I know if this thermostat will fit my specific engine model?
This thermostat is designed for MerCruiser 3.0L to 7.4L engines (1987+) with fresh water (closed) cooling systems. Please verify your engine model and required part number against our compatibility table and part number matrix for an exact match.
Is this thermostat for raw water or fresh water (closed) cooling systems?
This is a 160°F thermostat specifically designed for fresh water (closed) cooling systems only. It should not be used in raw-water cooled engines, which typically require a lower temperature thermostat (e.g., 140°F).
What are the signs of a failing thermostat?
Common symptoms include the engine overheating at normal operating speeds (stuck closed) or failing to reach its proper operating temperature (stuck open), which can lead to poor performance and increased fuel consumption. An erratic temperature gauge reading can also indicate a problem.
Can I replace just the thermostat without the housing?
Yes, this part is the thermostat itself and is designed to fit into your existing housing. However, it is critical to also replace the thermostat housing gasket during installation to prevent leaks.
What is the difference between a 160°F and a 140°F thermostat?
The temperature rating indicates when the thermostat opens. A 160°F thermostat is standard for most fresh water (closed-cooled) engines, allowing the engine to run hotter for better efficiency. A 140°F thermostat is used in raw-water (open-cooled) systems to reduce salt and mineral buildup.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials and manufactured in an ISO 9002 facility, with batch inspections for consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit is 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 and in original condition). See our policy page or reach out 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.
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