Sierra 18-3500 Thermostat, 140 Degree F, Replaces 437090, Fits Evinrude E115/E135/E150/E175 Outboards

The Sierra 18-3500 is a 140 degree F thermostat built for Evinrude outboard engines, regulating engine cooling water flow to keep the powerhead operating within its designed temperature range. Maintaining the correct opening temperature protects the engine from the damage caused by running too hot or too cold, and a worn or stuck thermostat is a common cause of overheating alarms and inconsistent engine temperatures. This thermostat is constructed of metal for durability in the marine cooling system environment and is engineered to meet or exceed the performance of the original equipment part it replaces.

The 18-3500 is a direct fit for specific Evinrude outboard models and years as listed below, and it cross-references to OEM part number 437090, making it a straightforward like-for-like replacement during routine cooling system maintenance or when troubleshooting an overheating condition.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3500
• Product Type: Thermostat
• Temperature Rating: 140 degrees F
• Material: Metal
• Weight: 0.05 pounds
• UPC: 808282159689
• Replaces (OEM): 437090
• Fitment: Evinrude E115 (1997); Evinrude E135, E150, E175 (2000-06)

Fitment

• Evinrude E115 (1997)
• Evinrude E135, E150, E175 (2000-06)

Replaces (OEM)

• 437090

Frequently Asked Questions

What temperature rating is the Sierra 18-3500 thermostat? The Sierra 18-3500 is a 140 degree F thermostat, meaning it begins to open at that temperature to regulate engine cooling water flow.

Which Evinrude outboards does the 18-3500 thermostat fit? It fits the Evinrude E115 (1997 model year) and the Evinrude E135, E150, and E175 (2000-06 model years).

Does the Sierra 18-3500 replace OEM part 437090? Yes, the 18-3500 is a direct cross-reference to OEM part number 437090.

What is the 18-3500 thermostat made of? It is made of metal, providing durability for use in the marine engine cooling system.

How much does the Sierra 18-3500 thermostat weigh? It weighs 0.05 pounds.

Is the Sierra 18-3500 a genuine OEM part or an aftermarket replacement? It is a Sierra-manufactured replacement thermostat engineered to meet or exceed the performance of the original 437090 part it replaces, not a repackaged OEM component.

Will a stuck or worn thermostat cause my outboard to overheat? Yes, a failed thermostat is a common cause of overheating alarms and inconsistent running temperature, which is why replacing it with a correctly rated part like the 18-3500 is important.

Does the 18-3500 fit engines outside the listed Evinrude E115/E135/E150/E175 range? Fitment for the 18-3500 is confirmed for the Evinrude E115 (1997) and E135, E150, E175 (2000-06); it should not be assumed to fit other models or years.

What is included when I order the 18-3500? The order includes one Sierra 18-3500 140 degree F thermostat.

What UPC does the Sierra 18-3500 thermostat use? The UPC for this thermostat is 808282159689.

Can I identify the correct replacement thermostat by the OEM number 437090? Yes, OEM number 437090 cross-references directly to the Sierra 18-3500 thermostat.