140°F (60°C) Thermostat Kit for MerCruiser V6/V8 Stern Drive Engines – Replaces 807252Q4, 807252T4, 807252T7, 8M0089715
140°F (60°C) Thermostat Kit for MerCruiser V6/V8 Stern Drive Engines – Replaces 807252Q4, 807252T4, 807252T7, 8M0089715 is backordered and will ship as soon as it is back in stock.
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140°F (60°C) Thermostat Kit for MerCruiser V6/V8 Stern Drive Engine...
140°F (60°C) Thermostat Kit for MerCruiser V6/V8 Stern Drive Engines – Replaces 807252Q4, 807252T4, 807252T7, 8M0089715 is backordered and will ship as soon as it is back in stock.
Product Details
This 140°F (60°C) thermostat kit is designed for MerCruiser V6 and V8 stern drive and outboard-drive cooling systems. It provides a complete thermostat-service solution with the thermostat, O-ring, and housing gaskets specified for the applicable assembly.
The thermostat is intended for systems that require a 140°F (60°C) opening temperature. Confirm the required temperature rating and the original part references for your exact engine before ordering.
- 140°F (60°C) thermostat for applicable MerCruiser V6/V8 cooling systems.
- Service kit includes the thermostat, O-ring, and multiple housing gaskets.
- Aftermarket replacement intended for direct replacement of the listed references.
- For stern drive and outboard-drive applications identified as MerCruiser V6/V8.
Part Number References
Use the following references to compare your original part and confirm compatibility. Reference numbers are provided for identification only; always verify the complete engine application.
| Reference Type | Part Number |
|---|---|
| Mercury/MerCruiser reference | 807252Q4 |
| Mercury/MerCruiser reference | 807252T4 |
| Mercury/MerCruiser reference | 807252T7 |
| Mercury/MerCruiser reference | 8M0089715 |
| Aftermarket/catalog reference | 18-3668 |
Compatibility
This kit is listed for MerCruiser V6 and V8 stern drive/outboard-drive applications. Compatibility can vary by engine configuration, cooling-system arrangement, production year, and serial-number range. The available product record does not establish a universal year or serial-number range for every V6/V8 engine.
Before installation, compare the thermostat temperature rating, housing gasket layout, and original part references with the contents listed below. Do not use this kit for a closed-cooling system unless the engine manufacturer specifies a 140°F thermostat for that system.
Technical Specifications
- Product Type
- Thermostat service kit with O-ring and housing gaskets
- Application
- MerCruiser stern drive/outboard-drive V6 and V8 engines
- Thermostat Temperature
- 140°F (60°C)
- Thermostat Reference
- 59137
- Cooling-System Use
- Verify the required thermostat rating and cooling-system configuration before installation
- Replacement Type
- Aftermarket replacement
What's in the Box
- 1 x Thermostat, reference 59137
- 1 x O-ring, reference 25-30224
- 1 x Gasket, reference 27-33179-2
- 1 x Gasket, reference 27-47510
- 1 x Gasket, reference 27-41812
- 1 x Gasket, reference 27-48818-1
- 1 x Housing gasket, reference 27-33918
Installation Notes
- Allow the engine to cool completely before beginning work. Disconnect the battery and follow the engine manufacturer's safety procedures.
- Identify the thermostat housing and place a suitable drain pan beneath the service area.
- Remove the housing fasteners and carefully separate the housing. Note the orientation of the original thermostat and gasket arrangement.
- Remove the old thermostat, O-ring, and gasket material. Clean and inspect all mating surfaces without damaging the housing or engine components.
- Install the 140°F thermostat in the correct orientation and replace the O-ring and applicable housing gaskets from the kit.
- Reinstall the housing and tighten the fasteners to the engine manufacturer's specified torque.
- Restore the cooling system using the correct procedure and fluid for the engine configuration. Check carefully for leaks.
- Run the engine while monitoring the temperature and water flow. Stop immediately if the engine overheats or a leak appears.
Troubleshooting & FAQ
How do I confirm that this kit is correct for my engine?
Confirm that your engine is a MerCruiser V6 or V8 stern-drive/outboard-drive application and that the original thermostat or service information references 140°F (60°C). Compare the original part references and gasket arrangement with the information on this page. If your engine has a closed-cooling system or a different temperature requirement, verify the specification with the engine manufacturer before ordering.
What does the kit include?
The kit includes one 140°F thermostat, one O-ring, and six listed gaskets for the thermostat housing and related housing surfaces. Tools, replacement fasteners, coolant, and sealants are not included.
What are common symptoms of a failing thermostat?
A thermostat that is stuck open may allow the engine to run cooler than specified, while a thermostat that is stuck closed can cause overheating. Restricted water flow, damaged gaskets, and other cooling-system faults can produce similar symptoms, so inspect the complete system before replacing parts.
Is this an OEM part?
No. This is an aftermarket replacement kit listed against the reference numbers shown on this page.
Can I use this kit with any MerCruiser V6 or V8?
No universal fitment should be assumed. MerCruiser applications vary by model, cooling-system design, year, and serial number. Verify the original reference numbers, thermostat temperature, and gasket configuration before installation.
Safety & Important Information
- Work only on a completely cool engine and follow the manufacturer's service procedures.
- Verify the temperature rating, original part references, and gasket layout before purchase and installation.
- Do not rely on engine displacement alone to confirm compatibility.
- Professional installation is recommended when the correct housing configuration or cooling-system type is uncertain.
About Sea Sierra
- Marine Replacement Parts — We supply replacement components for marine service and repair applications.
- Application-Focused Listings — Product information is organized around reference numbers, operating specifications, and installation considerations.
- Service-Ready Kits — This kit groups the thermostat, O-ring, and listed housing gaskets needed for the specified service application.
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