Thermostat Repair Service Kit for Mercruiser 4.3L 5.0L 5.7L 7.4L V6 V8 SternDrive Motors 807252Q4

Vendor: JLM Marine
Availability: In Stock
Product Type: Thermostat
$24.00
$24.00
Subtotal: $24.00

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photo thermostat kit 140 degree jlm marine 807252q4-18-3668 metal thermostat with brass cap black and reddish-brown gaskets for mercruiser 4.3l 5.0l 5.7l 7.4l 8.2l

Thermostat Repair Service Kit for Mercruiser 4.3L 5.0L 5.7L 7.4L V6 V8 SternDrive Motors 807252Q4

$24.00

Thermostat Repair Service Kit for Mercruiser 4.3L 5.0L 5.7L 7.4L V6 V8 SternDrive Motors 807252Q4

$24.00

Thermostat Kit 140°F – Fits MerCruiser 4.3L/5.0L/5.7L/7.4L V6/V8 SternDrive (Replaces 807252Q4)

This thermostat kit is designed for a wide range of Mercury MerCruiser V6 and V8 gasoline stern drive engines (262-454 CID) manufactured between 1983 and 2016 with standard cooling systems. It ensures your engine operates at the correct temperature for optimal performance and longevity.

It serves as a direct replacement for multiple OEM and aftermarket part numbers, providing a comprehensive solution for engine maintenance and repair. This kit is not intended for use in high-performance engine models.

  • Operating Temperature: Maintains a consistent 140°F (60°C) engine temperature.
  • Complete Solution: Includes the thermostat and all required gaskets and O-rings for a full replacement.
  • Broad Compatibility: Fits a wide variety of MerCruiser models from 1983 to 2016.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Brand Part Number
Mercury/MerCruiser 807252Q4
Mercury/MerCruiser 807252T4
Mercury/MerCruiser 807252T7
Mercury/MerCruiser 8M0089715
Sierra 18-3668
GLM 13390
Mallory 9-43150

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.

Model Engine Type CID Years OEM Part No. Notes
4.3L V6 175/185/205 262 (GM V6) 262 1985–1987 807252Q4 Model years 0A331455-0B775129
4.3L V6 262 (GM V6) 262 1987–1995 807252Q4 Model years 0B773243-0F601126
5.0L & 5.7L Small Block 305 (GM V8) 305 1983–1984 807252Q4 Model years 6218462-6899057
5.0L 305 (GM V8) 305 1988–1995 807252Q4 Model years 0B774445-0F600999
5.0LX 305 (GM V8) 305 1988–1995 807252Q4 Model years 5907058-0F600999
5.7L/5.7MIE/SKI 350 (GM V8) 350 1988–1995 807252Q4 Model years 0B773305-0F600999
7.4L/MIE 454 (GM V8) 454 1988–1994 807252Q4 Model years 0B771113-0F351999
GM V6 & V8 Various - 1983–2016 807252Q4 Standard cooling, except high performance engines

Technical Specifications

Specification Value
Product Type Thermostat Kit
Temperature Rating 140°F (60°C)
Installation Standard Cooling System
Application MerCruiser V6 & V8 Engines (except high performance models)
Weight 0.18 lbs (0.08 kg)
Warranty Limited Lifetime (Sierra)

Package Contents

1 x Thermostat (8M6002714/59137)
1 x O-Ring (25-30224)
1 x Gasket Thermostat Housing Cover (27-33179-2)
1 x Gasket Thermostat Cover (27-41812)
1 x Gasket Thermostat Housing (27-47510)
1 x Gasket Lower Housing (27-530451/27-48818-1)
1 x Gasket (27-33918)

Installation Guide

  1. Safety First: Disconnect the boat's battery before beginning work.
  2. Drain Coolant: Drain the engine coolant from the block to a level below the thermostat housing.
  3. Locate Housing: Find the thermostat housing, typically located where the large coolant hose from the circulating pump connects to the top of the engine.
  4. Remove Cover: Loosen and remove the bolts securing the thermostat housing cover.
  5. Remove Old Parts: Carefully lift off the cover and remove the old thermostat and gasket. Note the orientation of the thermostat.
  6. Clean Surfaces: Thoroughly clean the mating surfaces of the housing and cover, removing all old gasket material.
  7. Install New Thermostat: Place the new 140°F thermostat into the housing, ensuring it is oriented correctly.
  8. Install New Gaskets: Position the new gaskets as required by your specific engine model.
  9. Reassemble: Reinstall the housing cover and tighten the bolts to the manufacturer's specified torque.
  10. Refill Coolant: Refill the cooling system with the appropriate coolant mixture.
  11. Check for Leaks: Reconnect the battery, start the engine, and let it warm up. Carefully check for any leaks around the thermostat housing.
  12. Final Check: Once the engine reaches operating temperature, verify that the temperature gauge reads correctly and there are no leaks.

Troubleshooting & FAQ

How do I confirm this thermostat fits my MerCruiser engine?
This kit is designed for MerCruiser V6 and V8 engines (4.3L to 7.4L, or 262-454 CID) from 1983–2016 using a standard cooling system. To ensure a perfect match, please check your engine model and serial number against the "Compatible Engine Models" table. This kit does not fit high-performance models.

What is the operating temperature of this thermostat?
This is a 140°F (60°C) thermostat. This temperature rating is critical for raw water cooled marine engines to prevent salt and mineral buildup while ensuring the engine warms up to an efficient operating temperature.

My original part number is 807252T7. Will this kit work?
Yes. This kit is a direct aftermarket replacement for Mercury/MerCruiser part numbers 807252Q4, 807252T4, 807252T7, and 8M0089715, in addition to several other aftermarket brand numbers listed in the cross-reference table.

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.

We can ship to virtually any address in the world with free shipping available for most regions.

For our typical US and Canadian customers , our shipping timeframes are as follows:

  • Amazon FBA: orders will be delivered within 1-5 business days after placing the order (during certain special periods such as major promotions, Christmas, etc., the delivery time of Amazon FBA may be affected).
  • US warehouse shipment: orders will be delivered within 5 days after placing the order.
  • China warehouse shipment: orders will be delivered about 12 days after placing the order.

When you place an order, we will estimate shipping and delivery dates for you based on the availability of your items and the shipping options you choose. Depending on the shipping provider you choose, shipping date estimates may appear on the shipping quotes page.

Please also note that the shipping rates for many items we sell are weight-based. The weight of any such item can be found on its detail page. To reflect the policies of the shipping companies we use, all weights will be rounded up to the next full pound.

Founded in 2002, JLM Marine has established itself as a dedicated manufacturer of high-quality marine parts, based in China. Our commitment to excellence in manufacturing has earned us the trust of top marine brands globally.

As a direct supplier, we bypass intermediaries, which allows us to offer competitive prices without compromising on quality. This approach not only supports cost-efficiency but also ensures that our customers receive the best value directly from the source.

We are excited to expand our reach through retail channels, bringing our expertise and commitment to quality directly to boat owners and enthusiasts worldwide.

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