160° Thermostat Kit – Fits MerCruiser V6 & V8 4.3L-8.2L (Replaces 807252Q5, 8M0091470)

Product Details

This 160° Thermostat Kit is designed for MerCruiser V6 and V8 inboard/sterndrive engines from 4.3L to 8.2L (model years 1987–2016) that use a standard cooling system. It ensures your engine maintains the correct operating temperature for optimal performance and longevity.

It serves as a direct replacement for multiple OEM and aftermarket part numbers, including MerCruiser 807252Q5, 8M0091470, Sierra 18-3647, and GLM 13101.

• Designed for direct OEM replacement installation.
• Operates at a consistent 160°F (71°C).
• Includes all necessary gaskets and seals for a complete installation.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Engine & Model Compatibility

Confirm your engine model/year in the table below.

This thermostat kit is confirmed to fit the following MerCruiser engine models. Please check your engine's serial number against the ranges listed to ensure a correct fit.

Technical Specs

Product Type

Marine Thermostat Kit

Installation

Direct OEM Replacement

Housing Material

Plastic Sleeve

Operating Temperature

160°F (71°C)

Warranty

Varies by manufacturer (typically 1 year limited)

What’s in the Box

• 1 x Thermostat (807252T2)
• 1 x O-Ring (25-30224)
• 1 x Gasket (27-33179-2)
• 1 x Gasket (27-47510)
• 1 x Housing Sleeve (806922/23-806922)
• 1 x Gasket (27-48818-1)
• 1 x Gasket (27-33918)

Installation Notes

1. Disconnect the battery terminals to prevent accidental starting.
2. Allow the engine to cool completely, then drain the cooling system into a suitable container.
3. Locate the thermostat housing (typically where the main coolant hose connects to the engine).
4. Remove the bolts securing the housing and carefully separate it from the engine block.
5. Note the orientation of the old thermostat, then remove it. Clean any old gasket material from the housing and engine surfaces.
6. Install the new thermostat in the same orientation (spring side facing the engine).
7. Place the new gaskets and O-ring as required, then re-secure the housing, tightening bolts to the manufacturer's recommended torque.
8. Reconnect the main coolant hose, refill the cooling system, and check for any leaks.
9. Reconnect the battery, start the engine, and let it reach operating temperature, monitoring the gauge and checking again for leaks.

Troubleshooting & FAQ

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.