Thermostat Kit, 160° – Fits MerCruiser V6 & V8 Engines (Replaces 807252Q5)

Thermostat Kit, 160° – Fits MerCruiser V6 & V8 Engines (Replaces 807252Q5)

This thermostat kit is designed for MerCruiser V6 and V8 engines (4.3L, 5.0L, 5.7L, 7.4L, 8.2L) from model years 1987–2016 that require a 160°F thermostat and have standard cooling systems. It provides a reliable solution for maintaining optimal engine operating temperature.

This kit is a direct replacement for Quicksilver/Mercury part numbers 807252Q5, 807252T5, and 807252T8, as well as Sierra part number 18-3647.

• Includes a 160°F thermostat and a comprehensive set of gaskets and seals for a complete installation.
• Engineered as a direct OEM-quality replacement for standard cooling systems.
• Features a durable brass thermostat body with a new plastic sleeve.

Compatible Engine Models

Confirm your engine model/year in the table below. For Mercury owners, here’s a guide to help you identify your engine’s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

Technical Specifications

Package Contents

• 1 x Thermostat (807252T2)
• 1 x O-Ring Seal
• 1 x Cork Gasket (27-48818-1)
• 1 x Solid Housing Gasket (27-33179-2)
• 1 x Open Housing Gasket (27-47510)
• 1 x Open Base Gasket (27-53045-1)
• 1 x Open Base Gasket with Ground Rivets (if thermostat housing has sensor)
• 1 x Plastic Sleeve (23-806922)

Installation Guide

1. Disconnect the boat's battery terminals.
2. Drain the engine coolant into a suitable container.
3. Locate the thermostat housing and carefully remove the bolts or screws securing it.
4. Remove the old thermostat, sleeve, and any gasket remnants.
5. Thoroughly clean the mating surfaces of the housing and the engine block.
6. Insert the new plastic sleeve and thermostat into the housing, ensuring correct orientation.
7. Position the new gaskets and/or O-ring on the sealing surface.
8. Reinstall the thermostat housing and tighten the bolts to the manufacturer's specified torque.
9. Refill the cooling system with the appropriate coolant.
10. Reconnect the battery, start the engine, and carefully check for any leaks around the housing as it reaches operating temperature.

Troubleshooting & FAQ

How do I confirm this thermostat kit fits my MerCruiser engine?
Verify your engine model, year, and serial number against the compatibility table above. This kit is specifically for MerCruiser V6 and V8 models (1987-2016) with standard (raw water) cooling systems and is a direct replacement for OEM part 807252Q5.

What are common signs of a failing thermostat?
Symptoms include the engine overheating, the engine temperature gauge reading unusually low or fluctuating erratically, or visible coolant leaks from the thermostat housing area.

How often should a marine thermostat be replaced?
For preventative maintenance, it is recommended to inspect your thermostat annually and replace it every 2-3 years, or according to the service intervals specified in your engine's owner's manual.

Is this thermostat different from the OEM part?
This is a high-quality aftermarket kit designed to meet or exceed OEM specifications for materials, fit, and function. It offers a reliable, cost-effective alternative to the original Quicksilver part.

OEM vs. Aftermarket?
This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

How fast do you ship and how much does it cost?
We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

What is your warranty and return policy?
This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.