Sierra 18-3320

Keep your Mercruiser engine running smoothly on the water with this precision-engineered gasket kit. Designed as a direct replacement for the OEM 46-44292A4, it tackles the common wear points in exhaust manifolds, risers, and related components. Boat owners know how frustrating coolant leaks or exhaust corrosion can be— this kit seals it all up, preventing water intrusion and costly damage down the line.

Whether you're prepping for a busy boating season or fixing issues from last summer's adventures, swapping out old, brittle gaskets restores factory-level performance. No more white smoke on startup or mysterious overheating— just reliable power when you need it most.

Key Components and Coverage

This comprehensive kit includes everything needed for a full manifold and converter refresh:

• Exhaust manifold gaskets for both sides
• Riser and elbow gaskets
• Thermostat housing and water crossover gaskets
• Exhaust tube seals and O-rings
• Intake manifold gaskets where applicable

Crafted from durable, heat-resistant materials that withstand marine environments, these gaskets flex without cracking and seal tightly under pressure. They're a smart upgrade over stock parts that degrade faster in saltwater exposure.

Perfect Fit for Popular Mercruiser Engines

Engineered for GM-based V8 blocks, this kit supports a wide range of Mercruiser setups from the '80s through early 2000s. It fits 4.3L, 5.0L, 5.7L, 7.4L, and 8.1L models with Alpha or Bravo sterndrives. Always cross-check your serial number plate for exact match— common on small-block and big-block configurations.

Pro tip: Pair it with new risers if yours show pitting or elbow wear to avoid future headaches. This ensures your cooling system flows right and exhaust exits cleanly.

Why Boat Mechanics Rely on It

Unlike flimsy generics, these gaskets use premium composites that resist swelling from antifreeze or oil contamination. Installation is straightforward with no special tools required beyond basics like a torque wrench. Expect to shave hours off the job compared to piecemeal replacements.

Real-world benefits include reduced engine temps, quieter operation, and extended manifold life. Owners report hitting the water sooner without tow-truck drama— ideal for weekend warriors or charter captains.

Spotting Trouble and Simple Fixes

Watch for milky oil, steam from the exhaust, or rust streaks around manifold bolts. These signal gasket failure letting water mix with combustion. While you're in there:

• Clean mating surfaces with a plastic scraper— no wires that gouge aluminum.
• Apply thin RTV to corners prone to weep, but sparingly.
• Torque bolts in a crisscross pattern to even pressure.

A fresh install like this can add years to your powerhead's service life, especially if you flush after every saltwater run.

Frequently Asked Questions