Mercury – Quicksilver Thermostat | Cooling System Components | Marine-Grade Construction | 8M6010300

Overview

There’s a quiet confidence that comes from knowing your outboard is running at the exact temperature it was designed for. When the water’s calm and the morning air is cool, or when you’re pushing across choppy afternoon swells, you want your engine to stay steady and predictable. That’s exactly what the Quicksilver 8M6010300 thermostat delivers. It keeps your Yamaha 75–90 horsepower four-stroke running in its sweet spot — not too hot, not too cold — so you can focus on the water ahead, not what’s happening under the cowl.

Key Features

• Thermostat engineered for Yamaha 75–90 horsepower four-stroke outboards
• Meets all original equipment manufacturer specifications for temperature regulation
• Direct replacement for Yamaha OEM part number 6FP-12411-00
• Replaces aftermarket cross-reference 18-3641
• Thermostat only; hardware, gaskets, and seals sold separately
• Built to withstand long-term marine exposure and fluctuating water conditions
• Provides consistent warm-up times and optimal engine operating temperature

Engine & Boat Compatibility

• Fits Yamaha F75, VF75, F90, and VF90 four-stroke models
• Ideal for fishing boats, bay boats, pontoons, small center consoles, and aluminum skiffs
• Designed for outboards used in lakes, rivers, inshore saltwater, and offshore environments
• Suitable for both recreational and light commercial use

Performance & Practical Benefits

A well-regulated engine feels different — smoother, steadier, more predictable when you throttle up or settle into a slow drift. This Quicksilver thermostat acts as the gatekeeper of your cooling system, allowing the engine to warm up quickly and maintain the temperature range it needs for efficient combustion and long-term durability.

When a thermostat ages or fails, small problems start creeping in: sluggish warm-up, harder starts, uneven idle, even increased fuel use. Replacing it with a part that fits precisely and reacts reliably brings everything back into balance. With the 8M6010300 thermostat in place, the engine holds its temperature the way it should, the power curve feels tighter, and the whole outboard responds with the clean, confident behavior you expect from a Yamaha.

Installation is straightforward for most boat owners, and the difference is something you’ll notice from the first run — steadier performance, smoother transitions, and a sense of security that your engine isn’t fighting hidden temperature swings.

Why Buy OEM

When it comes to engine temperature control, precision is everything. An aftermarket thermostat might look the same, but variations in calibration or build quality can quietly wear on your outboard over time. Choosing a genuine Quicksilver thermostat means you’re installing a part built to Yamaha’s original standards, tested to handle real marine conditions, and trusted by boaters who don’t like surprises on the water.

It’s the kind of investment that pays for itself in reliability, fuel efficiency, and long engine life. If you want a part that fits right the first time and performs exactly as intended, OEM is the way to go.

FAQ

Q1: Which engines does this thermostat fit?

It fits Yamaha 75–90 horsepower four-stroke models, including F75, VF75, F90, and VF90.

Q2: What makes it better than aftermarket options?

OEM calibration, tighter tolerances, and proven long-term reliability in real marine environments.

Q3: How do I confirm it’s the right replacement?

Match it to Yamaha OEM number 6FP-12411-00 or consult your owner’s manual.

Q4: Can it be used in saltwater and freshwater?

Absolutely — it’s engineered for both and built to resist corrosion.

Q5: Is installation simple?

Yes. Most boaters with basic tools can install it quickly, especially with a service manual.