Maintaining a proper seal within the exhaust system is essential for the performance, cooling efficiency, and long-term reliability of any Mercury V6 outboard. The Mercury Exhaust Split Plate Adapter Gaskets seal the connection between the exhaust adapter plate and exhaust divider (split plate) assembly, helping contain exhaust gases while keeping cooling water where it belongs.
A failed gasket at this location can allow exhaust leakage, cooling system inefficiencies, water intrusion, and unwanted pressure loss. For that reason, replacing these gaskets whenever the powerhead, exhaust plate, or adapter plate is removed is considered standard practice during maintenance and rebuild work.
Buckshot Racing #77 supplies replacement exhaust split plate adapter gaskets manufactured to match the fitment and sealing requirements of the original Mercury components.
Two Available Fitment Options
Because Mercury used different exhaust adapter plate designs throughout production, these gaskets are available in two versions covering most Mercury V6 two-stroke outboards.
Option 1 — Mercury 2.5L & Late 2.0L V6 Applications
This gasket replaces Mercury part numbers 183071 and 183076 and is commonly used on many Mercury 2.5 Liter and later 2.0 Liter V6 outboards.
Applications include numerous Mercury and Mariner 135 HP, 150 HP, 175 HP, 200 HP, XR6, EFI, carbureted, and performance-oriented V6 models. It is also commonly encountered during service of various Mercury Racing and high-performance recreational applications utilizing the later-style exhaust adapter plate configuration.
Option 2 — Mercury 2.4L & Early 2.0L V6 Applications
This gasket replaces Mercury part numbers 99177, 99177-1, and 99177-2 and fits many earlier Mercury 2.4 Liter and 2.0 Liter V6 outboards.
Common applications include Bridgeport, 245 Carb, 200 HP, 175 HP, 150 HP, early XR-series engines, offshore applications, and numerous Mercury Racing performance platforms built around the legendary 2.4-liter architecture.
Because Mercury made running changes over several decades of production, verifying the original gasket or engine serial number is always recommended before ordering.
Why This Gasket Matters
The exhaust split plate adapter gasket serves as a critical barrier between exhaust passages and cooling water passages within the adapter plate assembly. Mercury's V6 two-stroke engines rely on carefully controlled exhaust flow and water routing to maintain proper operating temperatures and performance.
As exhaust gases exit the cylinders, they travel through the exhaust chest, divider plate, adapter plate, midsection, and gearcase. The gasket helps maintain proper separation between these systems while preventing leaks that can affect engine operation.
Over time, repeated heat cycles, vibration, water exposure, and exhaust pressure can cause gasket material to deteriorate. Replacing the gasket during service helps restore proper sealing and reduces the risk of future issues.
Recommended During Rebuilds and Major Service
Whenever the powerhead is removed or the exhaust adapter plate is disassembled, installing a new gasket is inexpensive insurance. Most professional Mercury technicians replace these gaskets during powerhead rebuilds, exhaust plate service, tuner replacement, adapter plate repairs, and midsection maintenance.
Proper sealing helps ensure reliable cooling-system operation, consistent exhaust flow, and long-term engine durability.
Final Thoughts from Buckshot Racing #77
The Mercury Exhaust Split Plate Adapter Gasket is a small but critical component in the cooling and exhaust systems of Mercury V6 two-stroke outboards. Whether servicing a 2.0L fishing motor, rebuilding a 2.4 Bridgeport, maintaining a 2.5 XR6, or restoring a Mercury Racing performance engine, replacing these gaskets helps ensure proper exhaust sealing, cooling-system integrity, and long-term reliability.
With fitment options covering both early and late Mercury V6 platforms, Buckshot Racing #77 continues to support the legendary two-stroke engines that remain popular with performance boaters, racers, and enthusiasts worldwide.
Contact Mike at 714-697-1716 or mike@buckshotracing77.com for technical support.