Thermostat Kit (160°F) – Fits Mercruiser 4.3L-8.2L SternDrive Motors (Replaces 807252Q5, 807252T8, 8M0091470)
Thermostat Kit (160°F) – Fits Mercruiser 4.3L-8.2L SternDrive Motors (Replaces 807252Q5, 807252T8, 8M0091470) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Thermostat Kit (160°F) – Fits Mercruiser 4.3L-8.2L SternDrive Motor...
Product Details
This aftermarket Thermostat Kit (160°F) – Fits Mercruiser 4.3L-8.2L SternDrive Motors (Replaces 807252Q5, 807252T8, 8M0091470) is designed for a wide range of Mercury/Mercruiser V6 & V8 SternDrive engines (4.3L, 5.0L, 5.7L, 7.4L, and 8.2L) manufactured between 1987 and 2016.
It serves as a direct cross-reference for Mercruiser parts 807252Q5, 807252T8, 8M0091470, and 8M0109441, and interchanges with Sierra 18-3647, GLM 13101, and Mallory 9-43157.
- Installs as a direct replacement for the original thermostat assembly.
- Maintains engine operating temperature at a consistent 160°F (71°C).
- Includes a complete set of gaskets, O-ring, and a housing sleeve for a full service.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercruiser | 807252Q5 |
| Mercruiser | 807252T8 |
| Mercruiser | 8M0091470 |
| Mercruiser | 8M0109441 |
| Sierra | 18-3647 |
| GLM | 13101 |
| Mallory | 9-43157 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercruiser | 4.3L | Various | 4-Stroke | 1987–2016 | 807252Q5 | All 4.3L SternDrive models |
| Mercruiser | 5.0L | Various | 4-Stroke | 1987–2016 | 807252Q5 | All 5.0L SternDrive models |
| Mercruiser | 5.7L | Various | 4-Stroke | 1987–2016 | 807252Q5 | All 5.7L SternDrive models |
| Mercruiser | 7.4L | Various | 4-Stroke | 1987–2016 | 807252Q5 | All 7.4L SternDrive models |
| Mercruiser | 8.2L | Various | 4-Stroke | 1987–2016 | 807252Q5 | All 8.2L SternDrive models |
Technical Specs
- Product Type
- Thermostat Kit with Gaskets and Housing Sleeve
- Installation
- Direct Replacement
- Temperature Rating
- 160°F (71°C)
- Housing Material
- Metal (Thermostat) / Plastic (Sleeve)
- Housing Color
- Metallic / Black
- Dimensions
- 5.98 × 4.02 × 2.05 inches (152 × 102 × 52 mm)
- Weight
- 1.76 ounces (50 grams)
- Exterior Finish
- Metallic
- Warranty
- 30-Day Return Guarantee
- Other Technical Attributes
- Complete service kit with all necessary gaskets and seals
What’s in the Box
- 1 × Thermostat 160°F (807252T2/808252)
- 1 × O-ring (25-30224)
- 1 × Gasket (27-33179-2)
- 1 × Gasket (27-47510)
- 1 × Housing Sleeve (806922/23-806922)
- 1 × Gasket (27-48818-1)
- 1 × Gasket (27-33918)
Installation Notes
- Disconnect the battery and allow the engine to cool completely.
- Drain the engine block cooling system to a level below the thermostat housing.
- Locate and remove the bolts securing the thermostat housing. Note the orientation of hoses.
- Remove the old thermostat, sleeve, and gasket material. Thoroughly clean the mating surfaces.
- Install the new thermostat (spring-side facing the engine) and correct gaskets as supplied in the kit.
- Re-install the housing and tighten bolts to the manufacturer's specified torque.
- Reconnect hoses and refill the cooling system with the appropriate coolant.
- Start the engine, check for leaks, and monitor the temperature gauge to ensure proper operation.
Troubleshooting & FAQ
How do I confirm this kit fits my engine?
Check your engine model and year against the compatibility table. The surest method is to verify that your existing part's number matches one of the OEM or aftermarket part numbers listed in the "Part Number Matrix" section.
What are the signs of a failing thermostat?
Common symptoms include engine overheating, the engine failing to reach normal operating temperature (running too cold), erratic temperature gauge readings, and coolant leaks from the thermostat housing area.
How often should a marine thermostat be replaced?
As a preventative maintenance item, it is wise to inspect the thermostat annually and consider replacement every 2-3 years, especially if the boat is used in saltwater. Replace it immediately if you notice cooling performance issues.
Why use a 160°F thermostat in a marine engine?
A 160°F temperature rating is common for raw-water cooled marine engines. It helps the engine reach an efficient operating temperature while helping to reduce the risk of salt and mineral deposit buildup that can occur at higher temperatures, which could restrict cooling passages.
Is this a complete kit for the job?
Yes, this is a comprehensive kit that includes the 160°F thermostat, a new plastic sleeve, an O-ring, and all the necessary gaskets for a standard thermostat replacement on compatible Mercruiser models.
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.
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