70981A3 3" Wet-Joint Exhaust Bellows Kit for MerCruiser 454/502 V8

SERDAMARINE / MARINE EXHAUST PARTS

Wet-Joint Manifold Exhaust Bellows Repair Kit for MerCruiser 3" Model 330–370 GM Big-Block V8

This wet-joint manifold exhaust bellows repair kit is built for MerCruiser Stern / Out Drive Model 330–370 V8 big-block GM 454/502 CID (1981 and up) applications equipped with a 3" wet-joint exhaust setup. It pairs the upper exhaust bellows reference 70981A3 with the gasket reference 27-863724 for manifold exhaust bellows service on the specified wet-joint configuration.

Configuration & Specifications

Engine Applications

This kit applies to the MerCruiser wet-joint big-block V8 configuration listed below. Match the existing bellows, the gasket’s water-passage layout, and the cooling configuration rather than selecting solely by engine displacement or sterndrive name.

• MerCruiser Stern / Out Drive Model 330–370, V8 B.B., GM 454/502 CID — Years: 1981 & up. Exhaust configuration: Wet Joint, Model 3". Fits when specified

Additional model-specific applications

• MerCruiser MODEL 330-370, 454 CID, V8 B.B., GM, wet-joint exhaust configuration; 1981 onward, end year not specified. Original designation: “WET JOINT MODEL 3 ″”.
• MerCruiser MODEL 330-370, 502 CID, V8 B.B., GM, wet-joint exhaust configuration; 1981 onward, end year not specified. Original designation: “WET JOINT MODEL 3 ″”.

Reference Numbers

The numbers below are provided for part identification and cross-checking; they do not by themselves guarantee direct interchangeability across every assembly or indicate original manufacturer identity. Note that 70981A3 (upper bellows reference) and 27-863724 (gasket reference) identify individual exhaust-system components rather than interchangeable part numbers for the complete kit.

Supplied Parts

• Wet-joint manifold exhaust bellows repair kit

Service & Installation Notes

General service guidance only. Use the service manual for your exact engine and exhaust configuration.

1. Shut down the engine, allow the exhaust system to cool completely, and disconnect the battery to prevent accidental starting during service.
2. Drain the wet-joint exhaust passages according to the engine service manual before loosening the exhaust bellows or disturbing the joint sealing surfaces.
3. Support adjoining exhaust components as needed, remove the worn bellows and old gasket material, and clean all mating surfaces without gouging the metal.
4. Compare the replacement upper bellows and gasket directly against the removed parts, paying close attention to the wet-joint water-passage layout and orientation.
5. Install the components following the alignment, clamping, and fastener tightening procedures specified in the OEM service manual.
6. After reassembly, supply cooling water and inspect the exhaust joint and bellows area for water or exhaust leaks at idle. Shut down immediately and inspect if any leakage or abnormal temperature is observed.

The Serdamarine Approach

Exhaust parts need a configuration match. Serdamarine focuses on marine exhaust manifolds and their related service parts. Application details, connection requirements and public reference numbers are presented together to support part selection.

Questions Before Replacement