0435491 Evinrude Johnson Thermostat AY | Genuine OEM BRP Outboard Part

🔧 Product Description

Genuine BRP Evinrude Johnson 143°F Thermostat Assembly - Part Number: 0435491

A genuine BRP cooling-system thermostat for selected 90HP, 115HP, 150HP and 175HP Evinrude and Johnson two-stroke outboards.

The thermostat begins opening at approximately 143°F or 62°C, regulating cooling-water circulation through the cylinder block and cylinder heads. Correct temperature control helps the engine warm up evenly while preventing excessive operating temperature under load.

⚙️ Key Features

• Genuine BRP Evinrude Johnson OEM thermostat
• Correct OEM part number 0435491
• Common unprefixed number 435491
• Approximately 143°F / 62°C opening temperature
• Used on selected 60-degree V4 and V6 engines
• Wax-pellet thermostat construction
• Sierra and Mallory replacements available

🚤 Compatibility

Typically suits selected

• 90HP: approximately 1995-2006
• 115HP: approximately 1995-2006
• 150HP: approximately 1993-2006
• 175HP: approximately 1993-2006
• 60-degree V4 and V6 two-stroke engine families
• Carburetted, FICHT and applicable direct-injection engines whose diagrams specify 0435491

Important fitment note

• Some engines require one thermostat per cylinder bank.
• Confirm the quantity required by the cylinder-and-crankcase diagram.
• Do not substitute thermostat 0436195 solely because it has a similar temperature rating.
• Grommets, seals, covers, springs and diaphragms are separate unless specifically included.

🔌 Function

The thermostat restricts water flow during warm-up and opens progressively as the engine reaches operating temperature.

Installation considerations

• Replace thermostats in matched pairs where the engine uses two
• Inspect thermostat covers and sealing surfaces
• Replace damaged grommets and seals
• Remove salt deposits from the thermostat cavity
• Do not scratch aluminium sealing surfaces
• Confirm the replacement begins opening near 143°F / 62°C
• Check cooling-water flow after installation
• Verify both cylinder-bank temperatures during operation

⚠️ Common Signs of Failure

• Engine overheats at idle or under load
• One cylinder bank runs hotter than the other
• Engine remains excessively cold
• Over-temperature warning activates
• Salt deposits prevent the thermostat from moving
• Thermostat remains open when cold
• Thermostat does not open in heated water
• Rubber seal or thermostat frame is damaged

🔄 Supersession & Cross Reference

OEM / Related Numbers

• 0435491
• 435491
• Mercury / Quicksilver: 8M6010305
• OEM Description: Thermostat Assembly
• Temperature Rating: Approximately 143°F / 62°C
• Thermostat diaphragm and pressure-control components vary by engine model

Aftermarket / Verified Equivalents

• Sierra: 18-3544
• Mallory: 9-43032
• Aftermarket 143°F thermostat replacing 0435491
• Generic replacement cross-referenced to 435491 and 8M6010305

📦 Condition

• Genuine BRP Evinrude Johnson OEM part
• Brand new
• Supplied in genuine or equivalent protective packaging