Sierra 18-3329 Grommet Watertube9.9-35 30249

Enhance Your Outboard Engine's Cooling System with the Sierra 18-3329 Grommet

Keeping your boat's engine running smoothly starts with reliable cooling. The Sierra 18-3329 grommet serves as a critical seal for the water tube in smaller outboard motors, preventing leaks that could lead to overheating and costly repairs. Designed as a direct replacement for OEM part 30249, this durable grommet fits snugly into place, ensuring water flows efficiently from the pump to the engine block without seepage.

Crafted from high-quality, marine-grade rubber, it resists the harsh effects of saltwater, fuel residues, and constant vibration. Boaters who maintain their own vessels know how a simple worn grommet can disrupt performance—replacing it promptly restores optimal cooling and extends engine life.

Perfect Fit for 9.9 to 35 HP Mercury Outboards

This grommet is engineered specifically for Mercury outboard engines in the 9.9 to 35 horsepower range, covering popular models from various years. It slots seamlessly into the water tube housing, matching the original specifications for hassle-free installation. Whether you're prepping for a fishing trip or routine servicing, having this part on hand means less downtime on the water.

• Direct OEM equivalent: 30249
• Compatible with inline and loop-cooled systems
• Suits single and twin-cylinder configurations

Verify your engine's model against Sierra's compatibility charts for the best match—precision fitment is key to avoiding vibrations or premature wear.

Key Features That Stand Out

What sets the Sierra 18-3329 apart? It's not just a grommet; it's built for longevity in demanding marine environments.

• Superior Sealing: Compresses tightly to block water intrusion and air pockets.
• UV and Ozone Resistant: Maintains flexibility even after prolonged sun exposure.
• Easy Inspection: Visually check for cracks or hardening during annual tune-ups.
• Cost-Effective Maintenance: Prevents expensive water pump or impeller failures downstream.

Users report it outperforming generic alternatives, holding up through seasons of heavy use in both freshwater lakes and coastal bays.

Step-by-Step Installation Guide

Swapping out a water tube grommet is a quick DIY task that takes under 30 minutes with basic tools. Here's how to do it right:

1. Disconnect the fuel line and run the engine dry to drain residual water.
2. Remove the lower unit or access the water tube from the powerhead side.
3. Pry out the old grommet carefully using a flathead screwdriver—avoid damaging the tube.
4. Clean the seating area with a rag and mild solvent to remove debris.
5. Lubricate the new Sierra 18-3329 grommet with marine grease and press it firmly into place.
6. Reassemble, reconnect hoses, and test-run the engine while checking for leaks.

Pro tip: Always flush the cooling system post-install to clear any old sediment. If you're new to this, watch for the telltale signs of improper seating, like erratic water telltale stream.

Troubleshooting Common Cooling Issues

A failing grommet often mimics other problems, like a bad impeller. Look for these symptoms:

Addressing these early keeps your outings uninterrupted. Pair this grommet with fresh coolant additives for peak efficiency.

Long-Term Maintenance Tips

To maximize the Sierra 18-3329's lifespan:

• Inspect annually or every 100 hours of use.
• Rinse with freshwater after saltwater runs.
• Store engines vertically to minimize tube stress.
• Combine replacement with water pump service for comprehensive cooling refresh.

Boat owners who've adopted proactive habits swear by the peace of mind— no more mid-trip meltdowns.

Frequently Asked Questions