The Mercury 818298Q1 Aluminum Transom Bracket Anode, also commonly referenced as 818298, is a sacrificial corrosion-protection anode designed to help protect Mercury outboards from galvanic corrosion and electrolysis.
 
Mounted on the transom bracket or power trim assembly, this anode is intended to corrode before more expensive aluminum components, helping extend the service life of the engine and bracket assembly.
 
Although often overlooked during routine maintenance, anodes are one of the most important defense systems against corrosion in both freshwater and saltwater environments. Replacing worn anodes at regular intervals is significantly less expensive than repairing damaged brackets, trim components, or gearcase housings.
 
Why Transom Bracket Anodes Matter
 
When dissimilar metals are immersed in water and electrically connected, galvanic corrosion can occur. Mercury utilizes sacrificial anodes throughout its outboard product line to help protect critical aluminum castings from this process.
 
The 818298Q1 anode is positioned to protect components within the transom bracket and power trim system. As the anode gradually deteriorates, it sacrifices itself to help prevent corrosion from attacking the engine's structural components. Routine inspection is recommended, and replacement should be considered whenever significant material loss is visible.
 
Aluminum Anode Advantages
 
Modern Mercury outboards are commonly equipped with aluminum anodes because they provide effective corrosion protection in freshwater, brackish water, and saltwater environments. Aluminum anodes typically offer longer service life than traditional zinc anodes while remaining active across a wider range of water conditions.
 
For many Mercury applications, aluminum remains the preferred replacement material because it matches Mercury's original corrosion-protection strategy and provides reliable long-term protection.
 
Broad Mercury Fitment
 
Note: Measures 7 5/8" x 2"
 
The Mercury 818298Q1 anode is used on a wide range of Mercury and Mariner outboards. Common applications include many 40 HP through 300 HP models, including numerous 3-cylinder, 4-cylinder, 6-cylinder, 2-stroke, EFI, DFI, Optimax, Pro XS, Verado, and FourStroke engines. It is also found on many Mercury Racing and high-horsepower V6 applications utilizing the transom bracket-mounted anode design.
 
Applications commonly include Mercury 150 HP, 175 HP, 200 HP, 225 HP, 250 HP, 300 HP, XRi, Pro Max, Optimax, 300X, 300XS, and numerous offshore and recreational outboards utilizing compatible transom bracket assemblies. Because Mercury used this anode across many model years and product families, serial-number verification is always recommended before ordering.
 
Cross Reference Information
 
The Mercury aluminum transom bracket anode is commonly identified as 818298Q1 and 818298. Additional Mercury references encountered in parts catalogs include 818298A1, 818298T1, 8M0059343, 8M0172259, 43396A1, and 43396A2. Various aftermarket manufacturers also offer equivalent replacements under their own numbering systems.
 
Recommended Maintenance
 
Anodes should be inspected regularly as part of routine engine maintenance. Paint, marine growth, heavy oxidation, or significant material loss can reduce effectiveness. Because anodes are designed to sacrifice themselves, gradual deterioration is normal and indicates the anode is performing its intended function.
 
Replacing a worn anode is inexpensive preventative maintenance that can help protect expensive transom bracket, trim, and mounting components from corrosion-related damage.
 
Final Thoughts from Buckshot Racing #77
 
The Mercury 818298Q1 and 818298 Aluminum Transom Bracket Anode is a simple but essential component in Mercury's corrosion-protection system. Designed to help safeguard transom brackets, trim assemblies, and surrounding aluminum components, it provides inexpensive protection against galvanic corrosion in a wide range of marine environments.
 
Whether you're maintaining a Mercury Optimax, Pro XS, Verado, 300X, 300XS, or a classic V6 two-stroke, routine anode inspection and replacement remains one of the easiest ways to help protect your investment and extend engine life.