Keep your OMC engine running smoothly with the Sierra 18-0965 gasket, a reliable replacement for the original OMC 338879. Designed for marine enthusiasts who demand precision and durability, this gasket seals critical exhaust components to prevent leaks, overheating, and performance issues that can sideline your boat during prime boating season.

Engineered for Superior Performance and Longevity

Crafted from high-quality composite materials, the Sierra 18-0965 withstands the harsh marine environment, including exposure to saltwater, high temperatures, and constant vibration. Unlike worn-out factory gaskets that crack or warp over time, this aftermarket solution maintains a tight seal, ensuring optimal exhaust flow and reducing the risk of corrosion in your engine's manifold or tube assembly.

• Exact fit for seamless installation without modifications
• Resistant to fuel, oil, and coolant for extended service life
• Meets or exceeds OEM specifications for peace of mind
• Helps maintain engine efficiency and fuel economy

Signs Your OMC Gasket Needs Replacement

Spotting gasket failure early can save you from costly repairs. Watch for white smoke from the exhaust, unusual engine noises, or water intrusion in the exhaust system. If you're experiencing reduced power or overheating on your OMC-powered stern drive, this gasket could be the fix. Regular inspections during routine maintenance—especially after 100 hours of use or annual tune-ups—keep your setup reliable.

Perfect Compatibility for OMC Stern Drives

The Sierra 18-0965 is tailored for select OMC inline engines commonly found in sterndrive applications. It fits models like the OMC 3.0L (181 cid) and similar configurations from the late 1970s through the 1980s, including popular Stringer 400 and 800 series. Always cross-reference with your engine serial number to confirm fitment, ensuring it integrates flawlessly with your existing hardware.

Simple Installation Tips for DIY Boaters

Replacing this gasket is a straightforward job for handy boat owners. Start by draining coolant and removing the exhaust manifold cover. Clean mating surfaces thoroughly to remove old gasket residue, then apply a thin layer of marine sealant if recommended for your setup. Torque bolts to factory specs—typically 15-20 ft-lbs in a crisscross pattern—to avoid warping. Reassemble, refill fluids, and test run at idle to check for leaks. Most jobs take under an hour with basic tools.

Pro tip: Pair this gasket with fresh exhaust gaskets and a tune-up for comprehensive engine health.

Why Sierra Stands Out in Marine Aftermarket Parts

Sierra has built a reputation for affordable, high-performance alternatives that match OEM quality without the premium price. Backed by rigorous testing, the 18-0965 gasket delivers consistent results season after season, trusted by mechanics and weekend warriors alike. Invest in reliability that gets you back on the water faster.