Thermostat Kit (120°) – Fits Mercury/Mariner Outboards 6-25 HP (Replaces Mercury 14586A3, Sierra 18-3549, GLM 13120, Mallory 9-43014/9-43052) 29HP Tighten the clamps to the

Tighten the clamps to the manufacturer's recommended torque to prevent leaks

A visual inspection showing a clogged

Clean the engine cowling of any dirt

Common symptoms include engine hesitation or sputtering

Thermostat Kit (120°) – Fits Mercury/Mariner Outboards 6-25 HP (Replaces Mercury 14586A3, Sierra 18-3549, GLM 13120, Mallory 9-43014/9-43052) 29HP Tighten the clamps to theProduct Details This Mercury Mariner Thermostat Kit (120) is designed for a wide range of Mercury and Mariner 2 stroke outboard engines from 6 to 25 HP, manufactured between 1984 and 1998. It ensures your engine maintains its optimal operating temperature for peak performance and longevity. The kit serves as a direct replacement for multiple OEM and aftermarket parts, including Mercury 14586A3, Sierra 18 3549, GLM 13120, and Mallory 9 43014 9 43052.