Sierra 118-3531 Thermostat Housing for MerCruiser Stern Drives

The Sierra 118-3531 (also referenced as 18-3531) is a replacement thermostat housing designed specifically for MerCruiser stern drive engines with closed cooling systems. This housing replacement kit fits V6 and V8 MerCruisers, compatible with MCM/MCI GM V6 and V8 (305, 350, 454, and 502 cu. in.) based marine engines with closed cooling systems.

Key Features:

• Engineered to match OEM housings to ensure the fit and function will be to factory specifications
• Includes the necessary seal to complete the installation
• Mating surfaces have been CNC machined to eliminate additional preparation
• Durable construction with non-corrosive, hard-wearing parts and components
• Manufactured to meet or exceed OEM requirements

OEM Cross-Reference:

• Mercury Marine 861188A1
• GLM 13540
• Mallory 9-42501

The engine's cooling system components take a beating - constantly heat cycled and exposed to salt water and fresh water, these parts corrode at a much faster rate than other engine parts. The Sierra 118-3531 provides a reliable, out-of-the-box solution for damaged or corroded thermostat housings in your MerCruiser cooling system.