Upper Exhaust Bellow – Fits MerCruiser Stern Drive 3.0L to 5.7L Engines V6/V8 (Replaces 70981A3)

Upper Exhaust Bellow – Fits MerCruiser Stern Drive 3.0L to 5.7L Engines V6/V8

This upper exhaust bellow is designed for a wide range of MerCruiser stern drive engines, including models such as 165/170/3.7L/180/190/470/485/488 (1980–1989), Chevy 305/350/377 (1983 and up), Big Block 454/502 (1981 and up), and V6 229/262 (1983 and up).

It serves as a direct replacement for multiple OEM and aftermarket part numbers, ensuring broad compatibility for various V6 and V8 engine configurations.

• Direct Installation: Fits securely with the two included stainless steel clamps.
• Durable Material: Constructed from high-grade CR (Chloroprene Rubber) for longevity and resistance to the harsh marine environment.
• Connection Type: Designed for a hose connection from a 3-inch center mounted riser to a 4-inch elbow.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Mercury owners, here’s a guide to help you identify your engine’s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

MerCruiser Inboard Gas Engines

MerCruiser Sterndrive Gas Engines

MerCruiser Sterndrive Diesel Engines

MerCruiser Inboard Diesel Engines

Technical Specifications

Package Contents

• 1 x Upper Exhaust Rubber Bellow (Replaces 70981A3)
• 2 x Stainless Steel Clamps

Installation Guide

Follow these general steps for installation. It is recommended to consult your service manual for model-specific instructions.

1. Safety First: Disconnect the boat's battery before beginning work.
2. Gain Access: Depending on your boat's configuration, remove any engine covers or components blocking access to the exhaust Y-pipe.
3. Locate the Bellow: Identify the existing upper exhaust bellow connecting the riser to the elbow.
4. Remove Old Clamps: Use a screwdriver or socket to loosen and remove the two clamps securing the old bellow.
5. Remove Old Bellow: Carefully work the old bellow off both the riser and elbow connections. This may require some twisting and pulling.
6. Clean Surfaces: Thoroughly clean the mounting surfaces on the riser and elbow to ensure a proper seal. Remove any old sealant or rubber residue.
7. Position New Bellow: Slide the new exhaust bellow into position, ensuring it is fully seated on both ends.
8. Install New Clamps: Place the new stainless steel clamps over the bellow at each connection point and tighten them securely. Do not overtighten.
9. Final Check: Once installed, reconnect the battery and run the engine, checking carefully for any exhaust leaks around the new bellow.

Troubleshooting & FAQ

How do I confirm this exhaust bellow fits my engine?
First, check the "Compatible Engine Models" table on this page. This part is designed for a wide range of MerCruiser engines from 1980 onwards. The surest way to confirm fitment is to cross-reference your existing part number with the numbers listed in the "Part Number Cross-Reference" section, such as Mercury 70981A3, Sierra 18-2762, or GLM 89070.

What are the common signs of a failing exhaust bellow?
A failed or cracked exhaust bellow will typically cause a noticeable exhaust leak inside the engine compartment. You might hear a louder engine noise, smell exhaust fumes, or see water leaking into the bilge area from the exhaust system. Visual inspection for cracks, perishing rubber, or looseness is also recommended.

How often should the exhaust bellow be inspected or replaced?
Exhaust bellows are a regular maintenance item. It is recommended to inspect them annually for signs of wear, cracking, or brittleness. Replacement intervals can vary based on usage (freshwater vs. saltwater) and exposure, but they are often replaced every 3-5 years or as needed during other stern drive service.

OEM vs. Aftermarket?
This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

How fast do you ship and how much does it cost?
We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

What is your warranty and return policy?
This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.