BH-Motor Exhaust Manifold Gasket Kit for Mercruiser 5.0 MPI / 5.7 / 350 Mag Riser V8 - Direct-Fit #39880, Complete Seal Kit

This gasket kit is engineered as a direct-fit replacement for worn or damaged exhaust manifold seals on Mercruiser 5.0 MPI, 5.7, and 350 Mag riser V8 engines, matching part numbers 39880 and 18-4349. The kit includes all necessary gaskets and seals to re-establish proper exhaust routing from the cylinder heads into the riser block, reducing exhaust leaks, improving backpressure control, and helping the engine run as intended. Components are manufactured to compatibility specifications so installation follows the factory fitment pattern.

How will this gasket kit improve my boat's exhaust performance?

Replacing aged or brittle exhaust manifold gaskets prevents exhaust gas leakage at the junction between manifold and riser. Proper sealing maintains exhaust flow integrity, which helps preserve engine efficiency and reduces the chance of exhaust heat or fumes entering the bilge or cabin areas.

• Restores factory-style sealing between manifold and riser block
• Limits exhaust leaks that can affect performance and noise
• Helps maintain correct backpressure for smoother operation
• Prevents corrosive exhaust gases from damaging adjacent parts

What parts are included and are they a direct replacement for part #39880?

The kit contains the exhaust manifold gaskets and related seals sized and shaped to replace Mercruiser part numbers 39880 and 18-4349. Each gasket matches the original mounting bolt pattern and sealing surfaces so you can swap them in without modifying the manifold or riser.

• Complete set of manifold-to-riser gaskets
• Seals made to match original equipment dimensions
• Fits the bolt pattern for Mercruiser 5.0 MPI, 5.7, and 350 Mag riser V8
• Sold as a kit for a full manifold replacement job

How difficult is installation and what tools are required?

Installation is a straightforward mechanical repair for someone with basic marine engine experience and common hand tools. The procedure normally involves removing the exhaust manifolds or riser connections, cleaning the mating surfaces, fitting the new gaskets, and torquing fasteners to manufacturer specs.

• Requires socket set, torque wrench, and gasket scraper
• Clean mating surfaces before installing new gaskets
• Follow torque sequence and specifications for even sealing
• Typical job for a weekend mechanic or marine technician

Will this kit fit my exact engine model and year?

This kit is specified for Mercruiser 5.0 MPI, 5.7, and 350 Mag riser V8 engines that use the OEM part numbers listed. Confirm compatibility by cross-referencing your engine's part number (39880 or 18-4349) or comparing the manifold bolt pattern to the old gasket before purchase.

• Designed to replace OEM #39880 and #18-4349
• Works with 5.0 MPI, 5.7, and 350 Mag riser V8 configurations
• Verify mating surface shape and bolt spacing prior to installation
• Contact BH-Motor support if you need help confirming fit

Who is this for: this BH-Motor exhaust manifold gasket kit is aimed at boat owners, marina technicians, and DIY mechanics maintaining Mercruiser 5.0 MPI, 5.7, or 350 Mag riser V8 engines. It's appropriate for anyone replacing deteriorated or leaking manifold gaskets who wants a direct-fit, cost-effective aftermarket option that replicates OEM sealing geometry and keeps exhaust routing secure and reliable.