Your Mercury deserves better than cheap aftermarket parts that fail after one season. This genuine THERMOSTAT, 49°C (120°F) SN# 0T997974 & Up COMPONENT OF POWERHEAD/PARTIAL ENGINE[61-840756A03] OR [61-840756A03] delivers the reliability your engine was built for.

Factory-built to exact Mercury Marine specifications, this thermostat ensures reliable operation across all engine RPM ranges. Part number 885599005 is manufactured to exact Mercury Marine factory specifications for precision installation and optimal performance. Constructed from premium marine-grade materials designed to withstand harsh saltwater and freshwater environments.

Cut-rate alternatives might look similar, but they’re not engineered to Mercury’s exacting standards. Part 885599005 delivers consistent performance because it’s built right — the same way Mercury does it at the factory.

Compatible Mercury Marine Engines

FITS: 250-300HP RACE OUTBOARD

• Fits RACE OUTBOARD 250-300HP engines
• Compatible HP: 250HP, 300HP
• Covers 3 serial number ranges
• Configurations: Outboard
• OEM genuine Mercury Marine part

COMPLETE SERIAL NUMBER COMPATIBILITY:

250HP Models

• 250HP OUTBOARD (Race Outboard): 0T997974-1E000796, 1E000797-1E002341

300HP Models

• 300HP OUTBOARD (Race Outboard): 0T429940-0T999587

Need help finding your serial number? Check our serial number location guide for step-by-step instructions on locating it on your Mercury engine.

Verification & Support

Not sure if part 885599005 fits your engine? Try our parts finder tool — it’s quick and easy. Need expert help? Contact us using the buttons at the bottom of this page – text, call, or email, whatever works best for you

40+ years of marine expertise. Low prices, fast shipping – most orders placed by 1pm ship today.