Mercury – Exhaust Elbow Gasket (Closed Cooling) | Cooling & Exhaust System | Marine Composite | 8637251

Overview
When you run a MerCruiser with a closed cooling system, every seal matters just a little more. You rely on the engine to keep its temperatures steady whether you’re cruising across calm morning water or pushing through a long afternoon chop. An exhaust elbow gasket may seem like a small detail, but when it’s the right one, you feel the difference in the way the engine settles into its rhythm. This Mercury Marine part brings back that sense of trust—quiet, dependable, and built to keep your system breathing clean and cool.

Key Features

• Designed specifically for MerCruiser closed cooling systems

• Built for V6 and V8 engines with center rise outlet exhaust manifolds

• Marine-rated composite construction for stable, leak-resistant sealing

• Matches the original gasket used on factory-installed systems

• Helps maintain proper cooling separation between seawater and coolant

• Manufactured to Mercury Marine OEM standards for long-term reliability

Engine & Boat Compatibility

• Fits MerCruiser V6 and V8 sterndrive and inboard engines made by General Motors

• Compatible with center rise manifolds used in select closed cooling configurations

• Common on cruisers, cabin boats, fishing vessels, day boats, and family runabouts with freshwater-cooled setups

• Works as a direct replacement for factory-installed exhaust elbow gaskets

Performance & Practical Benefits
Closed cooling engines operate a little differently, and they need parts that understand that balance. This gasket creates a precise, tight seal that keeps the coolant path separated from the raw-water side, ensuring that both systems function exactly as intended. The result is steady temperatures, smooth exhaust flow, and a sense of security that’s easy to appreciate when you’re miles from the dock.

Once installed, you’ll notice how clean and predictable the system behaves. No seepage. No uneven cooling. No sudden temperature spikes caused by a worn-out gasket. The material is designed for the harsh mix of heat cycles, vibration, and moisture that defines life inside a marine engine compartment. It stays firm, stays aligned, and holds its seal season after season. Installation is straightforward if you’ve done exhaust work before—just remove the old gasket, clean both surfaces, and torque down the elbow evenly. The moment it’s snug, you can feel the confidence returning to your setup.

Why Buy OEM
Choosing an OEM Mercury Marine part is more than a safe bet—it’s the smart, long-term option.

Here’s why:

• Exact fitment designed around MerCruiser cooling and exhaust architecture

• Materials engineered specifically for marine temperatures, moisture, and vibration

• No guesswork, trimming, or “making it work”—it fits right the first time

• Protects manifolds, elbows, and cooling components from premature wear

• Gives you reliability you can feel every time the engine fires up

If you want the part that matches the original performance and keeps your engine running like it should, OEM is the way to go.

FAQ

Q1: Which engines does the Exhaust Elbow Gasket 8637251 fit?
It fits V6 and V8 MerCruiser sterndrive and inboard engines equipped with center rise manifolds and closed cooling systems.

Q2: What makes this gasket different from aftermarket options?
This is the dedicated closed cooling design, engineered with marine-grade materials and exact waterflow pathways matched to OEM MerCruiser requirements.

Q3: How do I confirm it’s the correct replacement?
Check your cooling system type (closed cooling) and manifold style. Your owner’s manual or service guide will list the correct part number.

Q4: Can it be used on both saltwater and freshwater boats?
Yes—closed cooling systems paired with this OEM gasket perform reliably in any environment.

Q5: Is installation straightforward?
Most boat owners with basic mechanical experience can install it using standard hand tools and proper torque procedures.