Sierra 18-0339
Sierra 18-0339 Product Description
Upgrading or repairing your Mercury outboard just got simpler with the Sierra 18-0339 gasket, a direct match for the OEM 27-43006 part. Designed specifically for 8-cylinder engines, this intake manifold gasket seals tight against high-pressure environments, preventing leaks that could lead to overheating or power loss on the water. Boaters trust Sierra for its precision engineering that mirrors factory specs without the premium price tag.
Why Choose Sierra 18-0339 for Your 8-Cylinder Mercury Engine?
Sierra stands out in the marine aftermarket world by focusing on durability where it counts most. Crafted from high-grade materials resistant to saltwater corrosion, fuel blends, and extreme temperatures, this gasket withstands the rigors of long fishing trips or high-speed runs. Unlike flimsy generics, it features reinforced edges that maintain shape under compression, ensuring a reliable seal season after season.
- Perfect Fit Guarantee: Engineered to OEM tolerances for Mercury 8-cylinder models, dropping in effortlessly during routine maintenance.
- Leak-Proof Performance: Multi-layer construction blocks coolant, exhaust gases, and oil infiltration, keeping your engine running cool and efficient.
- Cost-Effective Reliability: Save big over dealer parts while getting the same quality—ideal for DIY mechanics and professional shops alike.
- Extended Engine Life: Proper sealing reduces wear on manifolds and heads, potentially adding years to your outboard's service life.
Real-World Applications and Compatibility Insights
Picture this: You're prepping for a weekend tournament, and a routine compression test reveals manifold leaks. Swapping in the Sierra 18-0339 restores factory-level vacuum and compression, boosting throttle response and fuel economy. It's a go-to for owners of classic big-block Mercurys used in bass boats, offshore cruisers, or pontoons. While always cross-checking your engine's serial number, this gasket shines in applications demanding robust sealing under heavy loads.
Installation Tips from Seasoned Mechanics
Getting this gasket on right is straightforward but rewards attention to detail. Start by draining coolant and removing the intake manifold—use a torque wrench set to spec for even pressure. Clean mating surfaces meticulously with a plastic scraper to avoid gouging aluminum. Apply a thin bead of marine sealant only where manufacturer guidelines suggest, then torque down in a crisscross pattern. Pro tip: Warm the engine post-install for a heat cycle to bed in the gasket fully. Most jobs wrap up in under two hours, saving shop labor costs.
- Disconnect battery and fuel lines for safety.
- Remove throttle body and accessories.
- Scrape old gasket residue without damaging surfaces.
- Position new Sierra gasket, align bolt holes precisely.
- Torque bolts gradually to avoid warping.
- Reassemble, refill fluids, and test run.
Maintenance Best Practices to Maximize Longevity
To keep your Sierra 18-0339 performing like new, inspect during annual tune-ups. Look for signs of weeping around bolt holes or discoloration from heat stress. Pair it with fresh coolant and fuel system cleaners to fend off degradation. Boaters in brackish waters report this gasket holding up 2-3 times longer than paper alternatives, thanks to its composite resilience. Regular checks mean fewer trailered breakdowns and more time chasing horizons.
Frequently Asked Questions
What engines is the Sierra 18-0339 gasket compatible with?
This gasket fits Mercury 8-cylinder outboards, serving as a reliable replacement for OEM 27-43006. Verify your model's year and serial for exact match.
How does Sierra 18-0339 compare to genuine Mercury gaskets?
Sierra matches OEM quality with superior materials for corrosion resistance, offering identical fit and performance at a fraction of the cost.
Can I install the Sierra 18-0339 myself?
Absolutely—basic tools and a service manual make it DIY-friendly. Follow torque specs to prevent issues.
What are common symptoms of a failed intake manifold gasket?
Watch for rough idling, coolant loss, white exhaust smoke, or reduced power. Early replacement avoids bigger engine damage.
Does this gasket require special sealant?
Use only marine-grade sealant on specified areas per your engine manual. Over-application can cause blockages.
How long does the Sierra 18-0339 typically last?
In marine conditions, expect 3-5 years or more with proper maintenance, outpacing many stock options.
Is the Sierra 18-0339 suitable for saltwater use?
Yes, its corrosion-resistant design excels in saltwater, freshwater, and everything in between.
Save $2 when you buy the Sierra 18-0339 for only $6 from NVN Marine! Same day shipping before 3pm.
Sierra 18-0339 Technical Specifications
| Type: | |
|---|---|
| Vendor: |
Sierra Engine Parts |
| Weight: |
0.01 lb |
Sierra 18-0339 User Reviews
Sierra 18-0339 Shipping & Return
| Shipping Weight: |
0.01 lb |
|---|---|
| Box Sizes: |
0.00 (h) x 6.00 (w) x 11.00 (l) |
| Cubic Feet: |
0.0 |
| Returnable: |
Yes |
For detailed shipping policy please check our Shipping Policy and you can find our Return and Refund Policy here.



