27-46820 Wet-Joint Exhaust Manifold Gasket Kit for MerCruiser 454/502

SERDAMARINE / MARINE EXHAUST PARTS

Wet-Joint Exhaust Manifold Gasket Repair Kit for MerCruiser GM 454 & 502 CID V8

This wet-joint exhaust manifold gasket repair kit services MerCruiser Models 330–370 with GM 454 CID and 502 CID big-block V8 engines from 1981 and up in 3-inch and 4-inch exhaust configurations. Component references covered within this multi-part kit include MerCruiser 27-46820, alongside raw-water-cooling, closed-cooling, full-flow elbow gasket, and drain plug components.

Configuration & Specifications

Engine Applications

Confirm the GM big-block V8 engine specification, installed wet-joint exhaust design, 3-inch or 4-inch exhaust configuration, and whether the manifold uses raw-water cooling or a center-riser closed-cooling arrangement before selecting the specific gaskets to install from the kit.

• MerCruiser Stern / Out Drive Model 330–370, V8 (Big Block), GM 454 / 502 CID — Years: 1981 & up. Exhaust configuration: Wet-joint exhaust manifold system, 3-inch and 4-inch configurations. Supports raw-water cooling and center-riser closed-cooling gasket selection, plus full-flow elbow gasket service. Fits when specified — match the included gasket type to the installed 3-inch or 4-inch wet-joint exhaust and raw-water or closed-cooling arrangement.

Additional model-specific applications

• MerCruiser MODEL 330-370, GM V8 Big Block, 454 CID, wet-joint exhaust, 3-inch and 4-inch configurations, from 1981 onward
• MerCruiser MODEL 330-370, GM V8 Big Block, 502 CID, wet-joint exhaust, 3-inch and 4-inch configurations, from 1981 onward

Reference Numbers

The numbers below are provided as identification references and do not by themselves guarantee interchangeability or indicate original manufacturer identity. The listed OEM and aftermarket numbers identify individual component references included across this repair kit; they are not interchangeable complete-kit part numbers.

Supplied Parts

The package contains two each of the five component types listed below:

• 2 × Exhaust manifold gaskets
• 2 × Raw-water-cooling gaskets
• 2 × Closed-cooling gaskets
• 2 × Full-flow elbow gaskets
• 2 × Drain plugs supplied with O-rings

Service & Installation Notes

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

1. Ensure the engine is shut off and completely cool, disconnect the battery to prevent accidental starting, and drain the exhaust manifold and cooling passages before disassembly.
2. Support heavy exhaust manifold and riser components during removal, and clean all mating surfaces carefully without gouging or damaging the sealing faces.
3. Identify whether the system uses raw-water cooling or a center-riser closed-cooling arrangement and match the required gasket pass-through configuration before assembly; do not install mismatched flow or block-off gaskets for your cooling setup.
4. Fit the drain plugs with their O-rings and tighten all fasteners according to the sequence and specifications in the engine service manual.
5. After assembly, run the engine only with a verified cooling water supply and inspect all manifold, elbow, and drain plug joints for water or exhaust leaks; stop the engine immediately if any leakage or overheating occurs.

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