Sierra Thermostat Kit 18-43052, Replaces 14586A3, Fits Mercury 6-25 HP 2-Stroke Outboards

The Sierra 18-43052 Thermostat Kit is a replacement engine thermostat built for Mercury 6-25 hp two-stroke outboard engines. As the powerhead's coolant regulator, the thermostat controls when raw water begins circulating through the cooling passages, helping the engine reach and hold its correct operating temperature. A thermostat that has failed open, closed, or is sticking is a common cause of overheating alarms, poor idle performance, or an engine that never comes up to temperature, and replacing it is a routine maintenance step for outboard owners.

This Sierra kit is manufactured as a direct equivalent to several Mercury Quicksilver thermostat part numbers, making it a straightforward drop-in replacement without needing to source the original OEM number. It is packaged under Sierra part number 18-43052 and is designed specifically for the 6-25 hp 2-Stroke Mercury outboard range.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-43052
• Product Type: Thermostat Kit
• Included Components: Thermostat
• Fitment: Mercury 6-25 hp 2-Stroke outboard engines
• OEM Cross Reference: 14586A3, 75962A9, 75962A10, 75962A11
• Weight: 0.08 pounds
• UPC: 808282342005

Fitment

• Mercury 6-25 hp 2-Stroke outboard engines

Replaces (OEM)

• 14586A3
• 75962A9
• 75962A10
• 75962A11

Frequently Asked Questions

What engines does the Sierra 18-43052 thermostat kit fit? The 18-43052 kit fits Mercury 6-25 hp 2-Stroke outboard engines.

Which OEM part numbers does 18-43052 replace? This thermostat kit replaces Mercury part numbers 14586A3, 75962A9, 75962A10, and 75962A11.

What is included with the 18-43052 kit? The 18-43052 kit includes the replacement thermostat for covered Mercury 6-25 hp 2-Stroke outboards.

How much does the 18-43052 thermostat kit weigh? It weighs 0.08 pounds.

Is the 18-43052 a genuine Sierra part or a generic aftermarket copy? It is manufactured by Sierra under part number 18-43052 and is built as a direct cross-reference replacement for the listed Mercury OEM thermostat numbers.

Is this thermostat for a 2-stroke or 4-stroke engine? The 18-43052 is designated for 2-Stroke Mercury outboard engines.

What horsepower range does the 18-43052 cover? It covers Mercury 6-25 hp outboard engines.

How can I confirm I'm ordering the correct thermostat? Match the UPC 808282342005 or Sierra part number 18-43052 against your engine's original thermostat packaging to confirm fitment.

Does the 18-43052 install in the same location as the original Mercury thermostat? Yes, since it is a direct replacement for Mercury numbers 14586A3, 75962A9, 75962A10, and 75962A11, the 18-43052 installs in place of the original thermostat on covered 6-25 hp 2-Stroke engines.

Will the 18-43052 fit other outboard brands besides Mercury? No, the fitment listed for 18-43052 is Mercury 6-25 hp 2-Stroke outboard engines only.