Corrosion is one of the leading causes of premature damage to marine engines, making sacrificial anodes one of the most important maintenance items on any outboard.
The Mercury 818298Q1 Aluminum Transom Bracket Anode, also identified as 818298, is engineered to protect the transom bracket, power trim assembly, and other aluminum components from galvanic corrosion and electrolysis before expensive structural parts are damaged.
Measuring approximately 7-5/8 inches by 2 inches, this OEM aluminum anode mounts directly to the transom bracket and gradually sacrifices itself to preserve the surrounding cast aluminum. Although inexpensive, it performs a critical role in extending the service life of Mercury and Mariner outboards operating in freshwater, brackish water, and saltwater.
How a Sacrificial Anode Protects Your Outboard
Whenever dissimilar metals are immersed in water and electrically connected, galvanic corrosion begins to attack the least noble metal. Mercury engineers prevent this by strategically placing sacrificial aluminum anodes throughout the outboard.
The 818298Q1 is specifically designed to protect the transom bracket and trim assembly, corroding first so the bracket, trim cylinders, mounting hardware, and other costly castings remain protected.
Unlike painted or structural components, the anode is intended to deteriorate over time. Visible material loss is normal and indicates the anode is performing as designed. Once a significant portion of the material has been consumed, replacement should be part of routine preventive maintenance.
Why Mercury Uses Aluminum Anodes
Modern Mercury outboards are equipped with aluminum anodes because they provide excellent corrosion protection in virtually every water condition. Compared to traditional zinc anodes, aluminum remains active in freshwater while also offering outstanding protection in brackish and saltwater environments.
Aluminum anodes generally provide longer service life, lighter weight, and improved overall efficiency, making them the preferred choice for today's Mercury FourStroke, Optimax, Pro XS, Verado, and Mercury Racing engines.
Fits a Wide Range of Mercury & Mariner Outboards
The Mercury 818298Q1 is used across an exceptionally broad range of Mercury and Mariner outboards spanning multiple generations. Compatible applications include many 40 HP, 45 HP, 50 HP, 55 HP, 60 HP, 65 HP, 75 HP, 80 HP, 90 HP, 100 HP, 115 HP, 125 HP, 135 HP, 140 HP, 150 HP, 175 HP, 200 HP, 225 HP, 250 HP, and 300 HP outboards.
It is commonly found on numerous 3-cylinder, 4-cylinder, inline-4, V6, FourStroke, EFI, DFI, Optimax, Pro XS, Sport XS, XS, Verado, SeaPro, Marathon, Jet Drive, BigFoot, XR6, Pro Max, 300X, 300XS, 250XB, 2.5L, 3.0L, 3.2L, and 3.4L Mercury outboards, as well as many Mercury Racing applications.
Because Mercury utilized this transom bracket anode across numerous engine families and production years, verifying compatibility by engine serial number remains the best method before ordering.
Inspection and Replacement
Sacrificial anodes should be inspected during every annual service or whenever the boat is removed from the water. Marine growth, paint, heavy oxidation, or debris can reduce an anode's effectiveness by limiting electrical contact with the surrounding water. Anodes should never be painted, as paint prevents them from functioning properly.
Replacement is recommended whenever approximately half of the original material has been consumed or if deep pitting and uneven wear are present. Regular inspection is inexpensive insurance against corrosion damage that can affect the transom bracket, trim assembly, mounting hardware, and adjacent aluminum castings.
OEM Cross References
The Mercury aluminum transom bracket anode is commonly identified by several part numbers throughout its production history, including 818298Q1, 818298, 818298A1, 818298T1, 8M0059343, 8M0172259, 43396A1, and 43396A2. These numbers are frequently encountered in Mercury parts catalogs and replacement guides for compatible engines.
Protect Your Investment
Whether your engine powers a fishing boat, pontoon, work boat, bass boat, offshore center console, or high-performance Mercury Racing hull, corrosion protection should never be overlooked.
The Mercury 818298Q1 Aluminum Transom Bracket Anode is one of the simplest and most cost-effective maintenance items available, helping protect thousands of dollars' worth of aluminum components from galvanic corrosion and electrolysis.
Replacing worn anodes at regular intervals helps preserve the reliability, appearance, and long-term value of your Mercury or Mariner outboard.
OEM Cross Reference
818298Q1, 818298, 818298A1, 818298T1, 8M0059343, 8M0172259, 43396A1, 43396A2