Inside Look: How Mercury Marine Builds its Engines

From scrap metal and castings to painting and testing

January 31, 2016
Recycled aluminum for engine parts

Raw Materials

Engine blocks start life at Mercury Castings, a business unit of Mercury Marine that started producing castings for the parent product line of marine engines and components nearly 70 years ago. These engine blocks start with recycled aluminum from the machining process, which are sent to the Mercury Castings facility to be re-melted. The resulting molten metal is cast into block components and parts further into the process. Courtesy of Mercury Marine

For more information about Mercury Castings, visit its website.

Raw material bins

Scrap Metal

In the Mercury Castings facility, large bins containing raw materials such as tin, copper, zinc, and aluminum are mixed. These materials are the components used to create Mercalloy, and they have been widely recognized in the industries beyond marine engines for their unique properties achieved at very favorable material and processing costs. Mercury Marine has successfully produced millions of marine engine and other parts over the years, which established the reputation of Mercalloy as “marine aluminum.” Courtesy of Mercury Marine
Melting furnace for blending alloys

Melting Furnace

Due to the extreme operating environment of marine engines, metallurgy and related manufacturing processes are exceptionally important, and are considered a core competency. Due to their superb strength-to-weight ratio and fair corrosion resistance, aluminum alloys are a good choice for marine engine components. This melting furnace is where the raw materials for these exclusive alloys come together. The raw materials and scrap metal are heated to prepare them for holding furnaces. Courtesy of Mercury Marine
Lost foam control station

Lost Foam Control Station

Most engine blocks Mercury produces starts out as a foam template, stamped with a unique serial number that stays with the engine the rest of its life. The ceramic-coated foam pattern is placed in a crucible that is filled with sand and then compacted. Courtesy of Mercury Marine
Pouring molten metal

Lost Foam Pour

Using “lost-foam casting” to produce intricate, single-piece engine parts isn’t new, but Mercury Marine put a new spin on improving the manufacturing technology to optimize its outboard technology and quality. In this process, molten metal is poured from a holding furnace through a sprue. The molten metal melts the foam and assumes its shape, replacing it with the Mercury-proprietary aluminum alloy. Courtesy of Mercury Marine

Read more about lost foam casting.

Engine block machining

Engine Block Machining

This Mazak machining cell machines Verado in-line four-cylinder and in-line six-cylinder engine blocks along with the bedplates. The block is machined in stages – pre-machining, qualifying machining, and assembly machining. These different stages require the block to be unloaded and reloaded onto different fixtures to allow certain features to be machined. Courtesy of Mercury Marine
Machining with robots


Robots aid certain machining steps for processing and transporting parts from one operation to another. This robot moves the engine block from a linebore machine to a washer. Courtesy of Mercury Marine
EDP paint line

EDP Paint Line

The powerhead components for Mercury Outboards and MerCruiser engines travel along a conveyor through electrodeposition paint (EDP) booths. This process is an important step in the exclusive Mercury Corrosion Protection system. EDP primer creates uniform coverage that seals out the environment. The powder paint top coat is harder, thicker and tougher than conventional paint. In the final step, these components are cured in infrared ovens. Courtesy of Mercury Marine
Robot torques bedplate


Robots assist with the assembly of Mercury outboards in the 75- to 115-horsepower range. At this station, the robot torques the bedplate to the engine block, which holds the crankshaft connecting rods and pistons in place. Courtesy of Mercury Marine
Assembling the block and components


Eventually, engine blocks are married to the other engine components on the assembly line. On this assembly line, the engine block travels from one station to another while assemblers attach the correct components at the correct time. Accuracy and quality are key in this process. Courtesy of Mercury Marine
Testing after assembly


Once engines are assembled, they are rigorously tested in a series of quality checks before being boxed and ready for delivery. Courtesy of Mercury Marine
Finished Mercury outboard

Finished Product

In the final stages of the process, Mercury engines are cleaned and ready to be boxed. As a final step, they are placed in sturdy shipping containers that will be delivered to a distribution center to await a customer order. Courtesy of Mercury Marine
Mercruiser assembly process

MerCruiser Assembly

Mercury MerCruiser sterndrive engines are assembled differently than outboard products. These engines travel through the assembly process on pallets, moving from station to station. The assembler’s work instruction is listed on a touch panel in the workstation, telling the assembler the procedure to perform. When the work element is complete, it is checked off on the touch screen, allowing the engine to move to the next station. Courtesy of Mercury Marine
Mercruiser testing

MerCruiser Testing

As a final stage for sterndrives, MerCruiser engines are placed in a testing room and connected to a diagnostic computer. This computer runs a series of tests to ensure the quality of the product before being boxed and ready for delivery. Courtesy of Mercury Marine

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