Sierra 18-1976-2 MerCruiser V6/V8 2002 & Older Manifold Elbow

Sierra 18-1976-2 MerCruiser V6/V8 GM 2002 & Older Manifold Elbow Replaces 807988A03

Unlike automotive engines, all marine inboards have exhaust risers that feature a water induction elbow. Located behind the engine’s coolant reservoir, the manifold elbow is a critical component to prevent water from entering the engine. It is also a target for corrosion and must be examined frequently and replaced as needed. Sierra, a leading aftermarket manufacturer offers the 18-1976-2 MerCruiser Manifold Elbow which is compatible with most MerCruiser V6 and V8 applications, 7 degree (4" O.D. Riser). This component is recommended for saltwater applications, additional product information follows:

Application:

MerCruiser V6 & V8 engines made by GM 2002 and older with a center rise outlet exhaust manifold

Includes:

• Exhaust Manifold 18-1953-2 for V8 305, 350, 377 engines 1983-2002
• Exhaust Manifold 18-1952-1 for V6 229 & 262 engines 1985-2002
• Exhaust Elbow Gasket 18-0897
• Pipe Plug 18-4258

Replaces:

• Barr
• MC-20-44354
• EMP
• 57-57513
• GLM
• 51140
• Mallory
• 9-40559
• MerCruiser
• 44354A3
• 807914A1
• 44354A9
• 44354A10
• 44354A13
• 807988A2
• 807988Q03
• 807988A03
• Osco
• 4354

Frequently Asked Questions

What does a manifold elbow do, and why does it need to be replaced?

Unlike automotive engines, marine inboards route cooling water through the exhaust system. The manifold elbow (also called the exhaust riser) sits atop the exhaust manifold and introduces raw water into the exhaust stream to cool it before it exits the boat. Because the elbow constantly handles hot exhaust gases and raw water simultaneously, it is highly susceptible to internal corrosion. A failed elbow can allow raw water to back-flow into the engine, causing catastrophic hydro-lock damage. As a general industry guideline, inspection every two years and replacement every 3 to 5 years depending on water conditions is commonly recommended.

What engines is the 18-1976-2 compatible with?

This elbow fits MerCruiser V6 and V8 engines manufactured by GM in 2002 and older, specifically those with a center rise outlet exhaust manifold. For V8 applications it pairs with the 305, 350, and 377 CID engines (1983–2002); for V6 applications it covers the 229 and 262 CID engines (1985–2002). It does not fit post-2002 dry-joint exhaust systems: those require the Sierra 18-1845.

What OEM part numbers does this replace?

This elbow replaces MerCruiser 807988A03 (and related superseded numbers 807988A2, 807988Q03, 44354A3, 44354A9, 44354A10, 44354A13, 807914A1). It also crosses to Barr MC-20-44354, EMP 57-57513, GLM 51140, Mallory 9-40559, and Osco 4354.

What is included with this kit?

The 18-1976-2 is a manifold elbow kit that includes the exhaust elbow itself, an exhaust elbow gasket (18-0897), and a pipe plug (18-4258). The compatible exhaust manifolds (Sierra 18-1953-2 for V8 engines or 18-1952-1 for V6 engines) are sold separately and are listed in the related products on the Wholesale Marine product page.

Is this elbow recommended for saltwater use?

Yes, this component is recommended for saltwater applications. The cast iron construction meets Sierra's OEM-equivalent standards. That said, saltwater environments are more aggressive than fresh water, so more frequent inspection intervals (annually rather than every two years) are advisable regardless of which elbow you run.

What are the warning signs that my manifold elbow needs replacement?

Common indicators include white or gray steam from the exhaust at startup that doesn't clear quickly, difficulty starting after the boat has been sitting, water in the engine oil, or visible external rust and pitting on the elbow itself. If a borescope or visual inspection reveals wall thickness below 1/8 inch at the water passages, replacement is overdue. When in doubt, replace both elbows at the same time; if one is corroded, the other is close behind.

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