Sierra 18-2833
Sierra 18-2833 — Product description
Keep your Mercruiser engine running smoothly on the water with the Sierra 18-2833 exhaust elbow gasket. Designed as a direct replacement for OEM Mercury part 27-99777, this high-quality gasket seals the exhaust elbow connection to prevent leaks, reduce backpressure, and maintain optimal engine performance. Sold in a convenient pack of two, it's perfect for routine maintenance or rebuilds on inboard and sterndrive applications.
Crafted from durable materials that resist the harsh marine environment—including saltwater corrosion, high heat, and vibration—this gasket ensures a reliable seal that extends the life of your exhaust manifold and risers. Boaters trust Sierra parts for their precise fit and OEM-level performance without the premium price tag.
Key Features and Benefits
- Precision Engineering: Matches factory specifications for seamless installation on compatible Mercruiser GM V6 and V8 engines.
- Superior Materials: Multi-layer construction with reinforced fibers handles exhaust gases up to 1,200°F and resists cracking over time.
- Leak-Proof Seal: Eliminates water intrusion and exhaust leaks, preventing costly overheating and corrosion damage.
- Pack of Two: Ideal for servicing both port and starboard sides during manifold riser replacements.
- Easy Maintenance: Simplifies annual service routines, helping you avoid breakdowns during peak boating season.
Engine Compatibility
This Sierra 18-2833 gasket fits a wide range of Mercruiser models equipped with GM-based engines from the 1980s through early 2000s. Commonly used on:
- 4.3L V6 (Alpha One, Bravo)
- 5.0L V8
- 5.7L V8
- 7.4L V8
Always verify your engine serial number against Sierra's compatibility charts or consult your service manual for exact fitment. It's a go-to choice for mechanics tackling dry joint exhaust systems.
Pro Installation Tips
- Drain coolant and remove exhaust risers/manifolds carefully to avoid damaging studs.
- Clean mating surfaces thoroughly with a non-abrasive scraper and solvent to ensure a flat seal.
- Apply a thin layer of high-temp RTV sealant around the gasket edges for extra protection against water jackets.
- Torque bolts to factory specs (typically 15-20 ft-lbs) in a crisscross pattern.
- Run the engine at idle for 10-15 minutes post-install, checking for leaks with soapy water.
Pro tip: Replace gaskets every 2-3 years or at 300-500 hours to stay ahead of corrosion buildup in saltwater use.
Long-Term Engine Health
Exhaust elbow gaskets like the Sierra 18-2833 are critical for preventing raw water from mixing with hot exhaust gases, which can lead to internal corrosion and white smoke issues. Regular inspection during haul-outs can spot early wear signs like blistering or softening. Pairing this gasket with fresh stainless steel risers maximizes your investment and keeps diagnostic trouble codes at bay.
Frequently Asked Questions
What Mercruiser models does the Sierra 18-2833 gasket fit?
It fits GM V6 and V8 engines in Mercruiser Alpha One and Bravo sterndrives, including 4.3L, 5.0L, 5.7L, and 7.4L models from various years. Confirm with your engine serial number.
Is the Sierra 18-2833 a direct replacement for Mercury 27-99777?
Yes, it's engineered as an exact OEM equivalent, ensuring proper fit and function without modifications.
How many gaskets are included in the Sierra 18-2833 pack?
The pack contains two gaskets, sufficient for both sides of a typical twin-exhaust setup.
Can I use this gasket in saltwater environments?
Absolutely. Its corrosion-resistant materials are ideal for brackish and saltwater boating, outperforming stock gaskets in longevity.
Do I need sealant with the Sierra 18-2833 installation?
A thin bead of high-temperature RTV around the outer edges is recommended for water jacket seals, but the gasket itself forms a reliable dry joint.
How often should I replace exhaust elbow gaskets?
Inspect annually and replace every 2-3 years or 300-500 hours, especially in corrosive marine conditions.
Will this gasket fix exhaust leaks and overheating?
Yes, by providing a tight seal, it prevents water intrusion and backpressure that cause overheating and smoke.
SKU: NVN-4003914
MPN: 18-2833
UPC: 808282258153
Technical specifications
| Brand | Sierra Engine Parts |
| Model | Sierra 18-2833 |
| SKU / MFR# | 4003914 |
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