GHmarine Upper Exhaust Hose Bellow 3–4" for MerCruiser — Direct-Fit with SS316 Clamps

GHmarine 70981A3 is a 3–4" upper exhaust hose bellow kit for MerCruiser stern drive engines, supplied with two SS316 clamps and built to replace OEM 70981A3/Sierra 18-2762-style bellows.

This replacement upper exhaust bellow is manufactured for MerCruiser stern drive applications and engineered to match the fit and function of common OEM and aftermarket references. It fits a wide range of V6 and V8 engines used with center-mounted risers and 4" elbows, offers stainless-steel clamps for a secure seal, and is intended as a direct-service component for routine maintenance or repair.

Which MerCruiser engines and manifolds will this bellow fit?

The GHmarine 70981A3 is designed to fit multiple MerCruiser manifolds and engines across several model years. It matches fits for older manifolds and popular Chevy-based sterndrive engines, so you can confirm compatibility before ordering.

• Fits manifolds: 165, 170, 3.7L, 180, 190, 470, 485, 488 (1980–1989).
• Engine fits include Chevy 305/350/377 (1983 and up) and big blocks 454/502 (1981 and up).
• Also suits V6 229/262 (1983 and up) and MerCruiser 3.0, 4.3, 5.0, 5.7 liter stern drive engines.
• Installs onto 3" 15° center-mounted risers with 4" elbow connections.

How durable and corrosion-resistant is the GHmarine bellow?

This exhaust bellow uses marine-grade materials chosen for long-term exposure to exhaust heat and saltwater environments. The included clamps are stainless steel 316 for superior corrosion resistance compared with ordinary steel clamps.

• Flexible hose material rated for exhaust temperatures and vibration absorption.
• Two SS316 clamps supplied to resist saltwater corrosion and hold a leak-free seal.
• Manufactured to aftermarket reference tolerances for reliable service life.

What is involved in installing the upper exhaust bellow?

Installation is straightforward for technicians familiar with stern drive exhaust systems: remove the old bellow, inspect mating surfaces, and mount the new hose with the supplied SS316 clamps. Proper seating on the 3" riser and 4" elbow, and correct clamp torque, ensure a durable exhaust seal.

• Remove and inspect riser and elbow ends for corrosion or pitting before fitting.
• Slide bellow over 3" center riser at 15° and over the 4" elbow per OEM alignment.
• Position supplied SS316 clamps and tighten evenly to recommended torque to avoid distortion.

Are there aftermarket part numbers or cross-references I should check?

This GHmarine unit cross-references common aftermarket and OEM part numbers so you can match it to existing listings or parts diagrams. Verify serial numbers and year to make sure the bellow matches the specific manifold and riser geometry on your boat.

• Aftermarket/OEM references: MerCruiser 70981A3, Mallory Marine 9-72808, Sierra 18-2762, GLM 89070.
• Confirm your outdrive model, engine serial number and production year before purchase.
• Recommended for replacement when bellows show cracks, leaks, or visible degradation.

Who is this for? Boaters and marine technicians who need a reliable, aftermarket replacement for a worn or leaking upper exhaust bellow on MerCruiser stern drive systems will benefit from this GHmarine kit. It’s aimed at owners of older MerCruiser-powered boats (1980s–1990s engine families and later Chevy-based sterndrive engines) who require a corrosion-resistant, direct-fit hose supplied with stainless clamps to restore exhaust sealing and reduce vibration and exhaust leakage risk. Always double-check engine model, manifold style, and serial data before ordering to ensure correct fitment.