Upper Exhaust Bellow for MerCruiser Stern Drives – 3-Inch Riser to 4-Inch Elbow, Replaces Mercury 70981A3
Upper Exhaust Bellow for MerCruiser Stern Drives – 3-Inch Riser to 4-Inch Elbow, Replaces Mercury 70981A3 is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
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Upper Exhaust Bellow for MerCruiser Stern Drives – 3-Inch Riser to ...
Upper Exhaust Bellow for MerCruiser Stern Drives – 3-Inch Riser to 4-Inch Elbow, Replaces Mercury 70981A3 is backordered and will ship as soon as it is back in stock.
Product Details
This Upper Exhaust Bellow is a replacement exhaust tube for selected MerCruiser stern drive applications. It is designed for the upper exhaust connection between a 3-inch center-mounted riser and a 4-inch elbow. The same application information also identifies the rear-mounted riser-to-4-inch Y-pipe configuration.
This single replacement bellow is listed for MerCruiser Stern Drive models 470/485, 898, 228, 250, 260, 280, and 330, as well as Ford 233 applications. The associated V8 application range is identified as 1971–1982; V6 and V8 fitment should be confirmed against the engine and exhaust configuration before ordering.
The primary manufacturer reference is Mercury 70981A3. Additional reference numbers listed for this product include Sierra Marine 18-2762, OBR MR-508, Mallory Marine 9-72808, and GLM 89070.
- Upper exhaust bellow for marine stern drive exhaust systems.
- Connects a 3-inch center-mounted riser to a 4-inch elbow.
- Also identified for a rear-mounted riser to 4-inch Y-pipe configuration.
- Sold as one bellow; clamps and other installation hardware are not included unless separately stated.
Part Number Matrix
Use the references below to compare the replacement part with your existing bellow and engine exhaust configuration. Reference numbers identify listed manufacturer or aftermarket applications; they do not replace a physical fitment check.
| Brand | Part Number | Reference Type |
|---|---|---|
| Mercury | 70981A3 | Primary manufacturer reference |
| Mercury | 70981A | Listed manufacturer reference |
| Sierra Marine | 18-2762 | Aftermarket reference |
| OBR | MR-508 | Aftermarket reference |
| Mallory Marine | 9-72808 | Aftermarket reference |
| GLM | 89070 | Aftermarket reference |
Engine & Model Compatibility
The company fitment record lists the following stern drive and engine applications. Model, exhaust layout, and connection dimensions must all match.
| Brand | Model or Engine | Configuration | Year Information | Fitment Notes |
|---|---|---|---|---|
| MerCruiser | 470 / 485 | Stern drive | Not specified | Upper exhaust bellow application |
| MerCruiser | 898 | Stern drive | Not specified | Upper exhaust bellow application |
| MerCruiser | 228 / 250 / 260 / 280 / 330 | Stern drive | Not specified | Upper exhaust bellow application |
| Ford | 233 | Marine engine application | Not specified | Confirm the exhaust connection layout before ordering |
| MerCruiser | V8 applications | 3-inch center-mounted riser to 4-inch elbow, or rear-mounted riser to 4-inch Y-pipe | 1971–1982 identified for V8 applications | Confirm the riser and elbow/Y-pipe arrangement |
| MerCruiser | V6 and V8 applications | Upper exhaust bellow configuration | Specific year range not stated | Verify model, exhaust layout, and dimensions |
Technical Specifications
- Product Type
- Upper exhaust bellow / exhaust tube
- Application
- MerCruiser stern drive exhaust system
- Primary Reference
- Mercury 70981A3
- Connection Configuration
- 3-inch center-mounted riser to 4-inch elbow
- Alternate Configuration
- Rear-mounted riser to 4-inch Y-pipe
- Product Quantity
- 1 bellow
- Clamps
- Not included
- Material
- Not specified by the product record
What’s in the Box
- 1 x Upper Exhaust Bellow
Clamps and other installation hardware are not included. Reuse existing hardware only if it is serviceable and appropriate for the installation, or obtain the required hardware separately.
Installation Notes
- Disconnect the battery and allow the engine and exhaust components to cool completely.
- Confirm that the replacement bellow matches the existing upper exhaust configuration, including the 3-inch riser and 4-inch elbow or Y-pipe connections.
- Gain clear access to the exhaust riser, elbow, and Y-pipe area.
- Loosen and remove the clamps or retaining hardware from the existing bellow.
- Remove the old bellow and inspect the mating surfaces, elbow, riser, Y-pipe, and clamps for corrosion, damage, or distortion.
- Clean the mating surfaces and remove debris without damaging the sealing surfaces.
- Position the new bellow in the same orientation as the original and seat it fully on both connections.
- Install suitable clamps or retaining hardware separately as required by the engine and exhaust configuration. Tighten according to the engine manufacturer’s service instructions and do not overtighten.
- Reconnect the battery and run the engine only with an appropriate water supply or on the water.
- Check carefully for exhaust, water, or cooling leaks before returning the boat to service.
Troubleshooting & FAQ
How do I confirm that this exhaust bellow will fit?
Compare your existing bellow with the listed references and verify the complete configuration: MerCruiser stern drive model, riser position, elbow or Y-pipe connection, and connection sizes. The primary reference is Mercury 70981A3, with Sierra Marine 18-2762, OBR MR-508, Mallory Marine 9-72808, and GLM 89070 listed as additional references.
Is this a complete exhaust bellow kit?
No. This product is a single upper exhaust bellow. Clamps and other installation hardware are not included.
What is the difference between an upper exhaust bellow and other bellows?
This part is for the upper exhaust tube connection. It should not be confused with a U-joint bellow, shift cable bellow, lower exhaust bellow, or a different-diameter exhaust boot.
What are common signs of a failed exhaust bellow?
Possible signs include exhaust or water leakage, exhaust odor in the engine compartment, unusual exhaust noise, visible cracking or splitting, and deterioration around the connection points. Inspect the surrounding exhaust components as well, since a damaged elbow, Y-pipe, or clamp can produce similar symptoms.
How often should the bellow be inspected?
Inspect the bellow during regular engine and stern drive service and whenever the exhaust system is disturbed. Replace it immediately if it shows cracks, hardening, deformation, separation, or leakage. A fixed replacement interval is not specified for this product.
Is this an OEM component?
This listing is for a replacement bellow associated with Mercury 70981A3 and the additional aftermarket references shown above. It is not presented as a genuine Mercury-branded component.
Shipping speed and cost
Standard shipping is free, with typical transit of 5–15 days. Expedited shipping options are shown at checkout where available.
Warranty and returns
This product is covered by a 1-year warranty against manufacturing defects under normal use. Returns are accepted within the standard return window when the item is unused and in its original condition. Contact support with your order details for assistance.
Safety & Important Information
- Verify the part reference, engine or stern drive model, exhaust layout, and connection dimensions before ordering.
- Do not rely on horsepower or model-year similarity alone; different exhaust configurations may use different bellows.
- Do not operate the engine without an appropriate water supply.
- Replace damaged, corroded, or unsuitable clamps and retaining hardware before installation.
- Professional installation is recommended when access is restricted or when the exhaust system has corrosion or structural damage.
About Sea Sierra
- Marine Replacement Parts — Components selected for common marine engine and stern drive service applications.
- Global Fulfillment — Standard delivery is available to most regions, with shipping options shown at checkout.
- Support When You Need It — Contact support with your engine model, existing part reference, and connection details if you need help confirming fitment.
Payment & Security
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