Mercury – Replacement Thermostat | 2-Stroke 30-60HP Outboards | Quicksilver | 850055001

Overview

There’s something reassuring about knowing your engine is running right where it should — not too hot, not too cold, just steady and strong. The Mercury Quicksilver 850055001 Replacement Thermostat keeps your outboard in that perfect temperature zone, so you can focus on the water, not your gauges. Whether you’re pushing through the backwater shallows or easing down a quiet river at sunrise, this part quietly does its job behind the scenes. It’s a small piece, sure, but it’s one that keeps your day on the water predictable and your motor running its best.

For those who spend their weekends boating, fishing, or guiding family adventures, there’s comfort in parts that simply perform. That’s what you get here — dependable Mercury Marine quality designed to keep your engine’s heartbeat steady, trip after trip.

Key Features

• Maintains precise engine temperature for optimal performance and longevity
• Designed specifically for Mercury and Mariner 2-Stroke 30-60HP outboards, including jet and BigFoot models
• Constructed from marine-grade materials built to handle continuous exposure to water and heat
• Engineered to Mercury Marine specifications for perfect fit and reliable operation
• Straightforward installation using common shop tools
• Tested for consistent response and long-term durability

Engine & Boat Compatibility

• Fits Mercury and Mariner 30-60 horsepower 2-stroke outboards
• Works with BigFoot and jet drive configurations
• Compatible with a wide range of small-to-mid-size boats, including fishing boats, pontoons, runabouts, and utility skiffs
• Ideal for both freshwater and saltwater conditions

Performance & Practical Benefits

A thermostat might not be the flashiest part on your motor, but you’ll feel its importance every time your engine fires up cleanly and stays smooth through the day. This Quicksilver 850055001 holds your Mercury outboard right in its optimal temperature range, ensuring efficient combustion, smooth idling, and strong throttle response.

A steady-running engine doesn’t just perform better — it lasts longer. Overheating is one of the biggest threats to any motor, and this thermostat acts as a quiet guardian, opening and closing with precision to balance coolant flow and protect internal components. You’ll notice easier starts, steadier power delivery, and peace of mind knowing your system is regulating itself the way Mercury intended.

Installation is simple and direct. With basic tools and a little patience, most boat owners can replace it themselves. Once it’s in, you’ll feel that subtle but satisfying confidence that comes from knowing you did it right — and that it’s going to stay that way.

Why Buy OEM

When you choose a genuine Mercury Marine part, you’re choosing precision and reliability that’s been proven on the water for decades. The 850055001 thermostat is built to the same standards as the one your engine left the factory with — no guessing, no adjustments, just the right fit and function every time.

Aftermarket parts can look similar, but the differences show up when the heat builds and reliability matters most. This OEM part is tested under real marine conditions to ensure long life and consistent performance. That means fewer breakdowns, smoother running, and more time spent doing what you love — boating.

FAQ

Q1: Which Mercury engines or systems does the Replacement Thermostat fit?

It fits Mercury and Mariner 2-Stroke 30-60 horsepower outboards, including BigFoot and jet drive models.

Q2: What makes this part different from aftermarket alternatives?

Mercury’s OEM design ensures perfect temperature regulation, superior materials, and long-term reliability that aftermarket parts rarely match.

Q3: How do I know if this is the correct replacement for my setup?

Check your service or owner’s manual for part number 850055001. If your engine falls in the 30-60HP 2-stroke range, this is the correct fit.

Q4: Can this be used in both saltwater and freshwater applications?

Yes. It’s constructed from corrosion-resistant materials designed to perform in both environments.

Q5: Is installation straightforward for most boat owners?

Definitely. It installs easily with standard tools and comes designed for a direct, no-modification replacement.