Thermostat Kit 14586A3 75962A9 for Mercury 2 Stroke 6 8 9.9 15 20 25 HP Outboard

Product Overview

Thermostat kit for Mercury two stroke outboards from 6 HP to 25 HP, opening at 50 °C (120 °F), replacing 14586A3, 75962A9, 75962A10 and 75962A11 and crossing to Sierra 18-43052. The kit is supplied as 1 x thermostat with the gaskets for the housing.

The 50 °C (120 °F) opening point is the cold running thermostat used on these small Mercury two strokes, not the higher temperature unit fitted to the four strokes. Fitting the wrong one is common, and it shows up as a motor that runs cold, makes water in the crankcase, or never gets off the cold start circuit.

The other failure is the opposite: the thermostat sticks shut and the motor overheats at speed within a couple of minutes. On a 6 HP to 25 HP outboard the telltale can still look fine with a stuck thermostat, because the telltale comes off the block before the thermostat, so check the head temperature by hand rather than trusting the stream.

Specifications & Attributes

OEM Cross Reference

Compatible Engines

What's Included

Condition & Warranty

Before You Buy

• Check the serial number from the table, not only the horsepower, the cut off is the serial number
• Confirm the old thermostat is the 50 °C unit, the four stroke motors use a hotter one
• Test the old thermostat in a pan of water with a thermometer, it should open at 50 °C and close again
• Clean the housing faces before the new gaskets go on, old gasket left behind is the usual leak
• Fit the thermostat the right way round, the spring and pellet go toward the block
• Check the telltale after the first start but feel the cylinder head as well, the telltale runs before the thermostat opens
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