160° Thermostat Kit – Fits MerCruiser V6 & V8 4.3L-8.2L Engines (Replaces 807252Q5)
160° Thermostat Kit – Fits MerCruiser V6 & V8 4.3L-8.2L Engines (Replaces 807252Q5) 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
Free standard shipping on all orders under 1 KG
160° Thermostat Kit – Fits MerCruiser V6 & V8 4.3L-8.2L Engines...
Product Details
This 160° Thermostat Kit – Fits MerCruiser V6 & V8 4.3L-8.2L Engines (Replaces 807252Q5) is designed for MerCruiser inboard and sterndrive engines with V6 and V8 configurations from 1987 and newer. It is primarily used for 4.3L, 5.0L, 5.7L, and 7.4L/8.2L engines, ensuring your engine operates at the correct temperature for optimal performance and longevity.
This kit serves as a direct replacement for MerCruiser part numbers 807252Q5, 807252T8, and 807252T5, as well as Sierra 18-3647 and Engineered Marine Products 807252Q5.
- Engineered for raw water cooled systems.
- Includes thermostat, plastic sleeve, O-ring, and all necessary gaskets for a complete installation.
- Designed for direct, hassle-free replacement of your original thermostat kit.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| MerCruiser | 807252Q5 |
| MerCruiser | 807252T8 |
| MerCruiser | 807252T5 |
| Sierra | 18-3647 |
| Engineered Marine Products | 807252Q5 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For MerCruiser engines, please verify your model and serial number range to ensure a perfect fit. The "& Up" designation for years indicates ongoing compatibility with newer models, which should be verified periodically.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| MerCruiser | 4.3L, 4.3LX, 4.3LXH Alpha | 190 | 4-Stroke | 1996–1997 | 807252Q5 | Serial Range: 0F601127-0K999999 |
| MerCruiser | 4.3L, 4.3LX, 4.3LXH Bravo | 190 | 4-Stroke | 1996–1997 | 807252Q5 | Serial Range: 0F601127-0K999999 |
| MerCruiser | 4.3L, 4.3LX GM | 190 | 4-Stroke | 1993–1995 | 807252Q5 | Serial Range: 0F000878-0F601126 |
| MerCruiser | 4.3L, 4.3LH, 4.3EFI Alpha | 190 | 4-Stroke | 1998 & Up | 807252Q5 | Serial Range: 0L010044 & Up |
| MerCruiser | 4.3L, 4.3LH, 4.3EFI Bravo | 190 | 4-Stroke | 1998 & Up | 807252Q5 | Serial Range: 0L010044 & Up |
| MerCruiser | 5.0L, 5.0LX GM | 220 | 4-Stroke | 1987–1995 | 807252Q5 | Serial Range: 0B525982-0F600999 |
| MerCruiser | 5.0L, 5.0EFI Alpha | 220 | 4-Stroke | 1998 & Up | 807252Q5 | Serial Range: 0L012052 & Up |
| MerCruiser | 5.0L, 5.0EFI Bravo | 220 | 4-Stroke | 1998 & Up | 807252Q5 | Serial Range: 0L012052 & Up |
| MerCruiser | 5.7L, 5.7LX GM | 260 | 4-Stroke | 1987–1995 | 807252Q5 | Serial Range: 0B525982-0F600999 |
| MerCruiser | 5.7L GM Alpha | 260 | 4-Stroke | 1995–1997 | 807252Q5 | Serial Range: 0F225560-0K999999 |
| MerCruiser | 5.7L GM Bravo | 260 | 4-Stroke | 1995–1997 | 807252Q5 | Serial Range: 0F225560-0K999999 |
| MerCruiser | 5.7L, 5.7EFI GM Alpha | 260 | 4-Stroke | 1998 & Up | 807252Q5 | Serial Range: 0L010037 & Up |
| MerCruiser | 5.7L, 5.7EFI GM Bravo | 260 | 4-Stroke | 1998 & Up | 807252Q5 | Serial Range: 0L010037 & Up |
| MerCruiser | 5.7L M IE | 260 | 4-Stroke | 1994–1997 | 807252Q5 | Serial Range: 0F025000-0K999999 |
| MerCruiser | 5.7L M IE | 260 | 4-Stroke | 1998 & Up | 807252Q5 | Serial Range: 0L002003 & Up |
| MerCruiser | 5.7L Ski | 260 | 4-Stroke | 1987–1998 | 807252Q5 | Serial Range: 0B514627 & Up |
| MerCruiser | 262 MAG Alpha | 260 | 4-Stroke | 1996–1997 | 807252Q5 | Serial Range: 0F803800-0K999999 |
| MerCruiser | 262 MAG Bravo | 260 | 4-Stroke | 1996–1997 | 807252Q5 | Serial Range: 0F803800-0K999999 |
| MerCruiser | 350 MAG | 300 | 4-Stroke | 1987–1997 | 807252Q5 | Serial Range: 0B525982-0F600999 |
| MerCruiser | 350 MAG EFI Ski | 300 | 4-Stroke | 1994–1997 | 807252Q5 | Serial Range: 0D505450-0K999999 |
| MerCruiser | 350 MAG MPI / M IE | 300 | 4-Stroke | 1998 & Up | 807252Q5 | Serial Range: 0L010019 & Up |
| MerCruiser | 350 MAG MPI Ski | 300 | 4-Stroke | 1995–1998 | 807252Q5 | Serial Range: 0F350583 & Up |
| MerCruiser | 350 MAG Ski | 300 | 4-Stroke | 1991–1997 | 807252Q5 | Serial Range: 0D505450-0K999999 |
| MerCruiser | 454 MAG MCM / Ski | 385 | 4-Stroke | 1995–1997 | 807252Q5 | Serial Range: 0F305000-0K999999 |
| MerCruiser | 7.4L, 7.4LX GM | 330 | 4-Stroke | 1996–1997 | 807252Q5 | Serial Range: 0F352000-0K999999 |
| MerCruiser | 7.4L M IE | 330 | 4-Stroke | 1989–1997 | 807252Q5 | Serial Range: 0C391564-0K999999 |
| MerCruiser | 7.4L MPI / TBI | 330 | 4-Stroke | 1995–1998 | 807252Q5 | Serial Range: 0F563052 & Up |
| MerCruiser | 8.2L M IE | 380 | 4-Stroke | 1993–1996 | 807252Q5 | Serial Range: 0D857200-0F819619 |
| MerCruiser | 8.2L MPI / M IE | 380 | 4-Stroke | 1996 & Up | 807252Q5 | Serial Range: 0F819620 & Up |
| MerCruiser | 502 EFI / MPI MCM | 415 | 4-Stroke | 1993–1997 | 807252Q5 | Serial Range: 0F802600-0K999999 |
| MerCruiser | 502 MAG MPI | 415 | 4-Stroke | 1998 & Up | 807252Q5 | Serial Range: 0L017000 & Up |
| MerCruiser | Scorpion Ski | - | 4-Stroke | 1996–1998 | 807252Q5 | Serial Range: 0F800000 & Up |
Technical Specs
- Product Type
- Thermostat Kit
- Installation
- Direct Replacement
- Thermostat Temperature
- 160°F (71°C)
- Housing Material
- Plastic Sleeve with Brass/Stainless Steel Thermostat
- Dimensions
- Height: 254 mm (10.0 in); Width: 279.4 mm (11.0 in); Length: 279.4 mm (11.0 in)
- Weight
- 0.07 kg (0.15 lb)
- Operating Temperature
- 160°F (71°C) opening temperature
- Warranty
- 1 year (aftermarket)
- System Application
- Raw water cooled systems
What’s in the Box
- 1 x Thermostat (Replaces 807252T2/8072522/8052732)
- 1 x O-ring (Replaces 25-30224/25-27018)
- 1 x Gasket (Replaces 27-331792/27-331791)
- 1 x Gasket (Replaces 27-41812/27-09556)
- 1 x Gasket (Replaces 27-47510)
- 1 x Gasket (Replaces 27-33918)
- 1 x Gasket (Replaces 27-530451/27-53045/27-33179)
- 1 x Plastic Housing Sleeve (Replaces 23-806922)
Installation Notes
- Ensure the engine is cool and disconnect the battery. Drain the engine coolant into a suitable container.
- Locate the thermostat housing on the engine. It is typically found where the main coolant hose connects to the top of the engine.
- Remove the bolts securing the housing. You may need to gently tap the housing to break the seal.
- Note the orientation of the old thermostat before removing it from the housing.
- Thoroughly clean the mating surfaces of the housing and the engine block, removing all old gasket material.
- Install the new thermostat into the housing in the correct orientation. Place the new gasket in position.
- Reinstall the housing and tighten the bolts to the manufacturer's specified torque.
- Reconnect all hoses, refill the cooling system with the appropriate coolant, and check for leaks.
- Start the engine and let it warm up to operating temperature, checking again for any leaks and verifying proper temperature gauge reading.
Troubleshooting & FAQ
What are the signs of a failing thermostat?
Common symptoms include engine overheating, the temperature gauge reading unusually low, erratic temperature fluctuations, and coolant leaks around the thermostat housing. A stuck-open thermostat will prevent the engine from reaching operating temperature, while a stuck-closed thermostat will cause rapid overheating.
Can I use this kit in a freshwater (closed) cooling system?
This thermostat is rated at 160°F, which is standard for raw water (open) cooled marine engines. Freshwater cooled engines typically use a higher temperature thermostat (e.g., 180°F-195°F). Using the wrong temperature thermostat can lead to improper engine performance and longevity issues. Please confirm the required temperature for your specific cooling system.
How do I know if my engine needs this specific 160°F thermostat kit?
Check your engine's service manual or consult the compatibility chart on this page. This kit is designed for the specified MerCruiser V6 and V8 models from 1987 onwards. Verifying your engine's serial number is the most reliable way to ensure correct fitment.
Is the plastic housing sleeve necessary for all installations?
Yes, the plastic sleeve is a critical component for many MerCruiser thermostat housings. It helps to properly position the thermostat and regulate coolant flow. Always install the new sleeve included in the kit to prevent potential cooling issues.
How often should I replace my engine's thermostat?
As a preventative maintenance item, it is a good practice to inspect your thermostat annually and replace it every 3-5 years, or immediately if you notice any signs of failure. For boats operated in saltwater, more frequent inspection and replacement may be necessary due to corrosion.
What is the difference between this aftermarket kit and an OEM part?
This is an aftermarket replacement part, not an OEM component. It has been engineered to meet or exceed original equipment manufacturer (OEM) specifications for fit, form, and function, providing a reliable and cost-effective alternative. It is manufactured in an ISO 9002 certified facility and undergoes batch inspections for quality.
What are the shipping costs and delivery times?
We offer fast, worldwide shipping. Standard shipping is typically free, with an estimated transit time of 5–15 days to most regions. Expedited shipping options may be available at checkout for an additional cost.
What is the warranty and return policy?
This product is covered by a 1-year warranty against manufacturing defects under normal operating conditions. If you encounter any issues, 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 policy page for full details.
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.
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