Sierra 18-2733

Keep your outboard motor running smoothly on the water with the Sierra 18-2733 G Water Shutter. This precision-engineered replacement part plays a crucial role in your engine's cooling system, ensuring optimal temperature control during those long days on the lake or ocean. Designed as a direct-fit substitute for OEM components, it restores factory performance without the premium price tag.

What Does the G Water Shutter Do?

The G water shutter, often found in Mercury and Mariner outboards, regulates water flow into the engine block. It opens and closes based on engine temperature, directing cooling water precisely where it's needed. When functioning properly, it prevents overheating in warm conditions and blocks excess cold water during startup to promote faster warm-up times. A faulty shutter can lead to erratic cooling, white smoke from the exhaust, or even engine damage from overheating—issues no boater wants to face miles from shore.

Why Choose Sierra 18-2733 for Your Outboard?

• Durable Construction: Made from high-quality, corrosion-resistant materials that stand up to saltwater exposure and freshwater use alike.
• Exact Fitment: Matches OEM specifications for seamless installation, saving you time and frustration in the repair yard.
• Performance Reliability: Helps maintain consistent engine temps, improving fuel efficiency and extending the life of your powerhead.
• Cost-Effective: A smart upgrade for routine maintenance or when troubleshooting cooling problems.

Boat owners rave about how this simple swap revitalized their motors, turning sluggish warm-ups into quick starts and eliminating those pesky overheating warnings.

Compatibility Guide

The Sierra 18-2733 fits a range of Mercury/Mariner 4-cylinder outboards, typically from 90 to 125 HP models produced in the 1980s through early 2000s. Common applications include the 90, 115, and 125 HP inline-4 engines. Always cross-reference with your engine's serial number to confirm fitment—check the thermostat housing area for the "G" marking on the original part. It's a popular choice for sport jet models too, where cooling efficiency is paramount.

Installation Tips for DIY Success

Replacing the water shutter is a straightforward job that most weekend mechanics can handle in under an hour. Here's a step-by-step overview:

1. Drain the cooling system and remove the thermostat housing cover.
2. Extract the old shutter—note its orientation for reinstallation.
3. Inspect the housing and gasket for wear; replace if needed.
4. Install the new Sierra 18-2733, ensuring it seats fully and moves freely.
5. Reassemble, refill with fresh coolant or water, and test run the engine on muffs.

Pro tip: Flush the cooling passages first to remove debris that could stick the new part. Wear gloves to avoid burns from residual heat, and monitor temps on your first outing post-install.

Maintenance Best Practices

To maximize the lifespan of your G water shutter, incorporate it into your annual service routine. Inspect it during thermostat changes, and watch for signs of failure like steam from the tell-tale or fluctuating temp gauges. Pair it with a quality thermostat and impeller for complete cooling system health. In saltwater environments, annual freshwater flushes are non-negotiable to prevent mineral buildup.

Equip your outboard with the reliable Sierra 18-2733 G Water Shutter and hit the water with confidence. Reliable cooling means more time boating and less time troubleshooting.