The Titanium Big Water Tube from Buckshot Racing #77 is a direct replacement for the large-diameter Mercury Racing copper water tubes used in high-performance 2-stroke V6 outboards. It is designed to replace Mercury water tube part numbers 32-8476504, 32-8476503, and 32-8476502, giving owners of legacy Mercury and Mercury Racing engines a durable alternative to the factory big copper tube.
 
Fitment and OEM Cross-Reference
This titanium tube line covers the main big-tube applications on Mercury 2.5L EFI V6 platforms, including popular performance models such as the 2.5 Liter 150, 200, 225HP Pro Max and Mariner SuperMagnum, related 260 EFI, 280 Race OffShore (ROS) 300 Drag, SST-120, SST-200, 200XS, S2000, and S3000.
 
For 12" mids with Super Speed Master SSM #4 (IV) or SSM #6 (VI) gearcases, the Titanium Big Water Tube matches the short OEM big tube, Mercury part number 32-8476504.
 
For 15" mids with SportMaster or TorqueMaster (ROS) gearcases, the 15" Titanium Big Water Tube corresponds to Mercury part number 32-8476503.
 
For 20" mids with SportMaster or TorqueMaster (ROS) gearcases, the 20" Titanium Big Water Tube replaces Mercury part number 32-8476502.
 
If your parts catalog or diagram calls out one of these three Mercury water tube part numbers, the matching Titanium Big Water Tube is the correct fitment.
 
Why Titanium Instead of Copper
Mercury originally used copper for the big water tube, and it works, but titanium offers several advantages in demanding racing and big-water use. Titanium is stronger and more impact-resistant than copper, so it handles vibration, handling, and service work with less risk of bending or kinking.
 
It is also highly resistant to corrosion in freshwater and saltwater, which helps maintain internal surface quality and flow over time. Because titanium is lighter than copper, it slightly reduces weight in the midsection. It is also less conductive of heat and static electricity, which can be beneficial in tightly packaged racing mids and gearcases.
 
Design, Sizing, and Cooling Performance
The Mercury Racing big water tube is not a standard 3/4-inch or common metric size. The original parts 32-8476504, 32-8476503, and 32-8476502 use specific outside and inside diameters so the tube seats correctly in the water pump housing, seals in the driveshaft housing bore, and provides the flow area Mercury designed for high-RPM cooling.
 
Buckshot Racing #77 has the Titanium Big Water Tube custom-made to match the original Mercury OD and ID for each part number. This means the titanium tube slides into the pump housing and midsection just like the factory big tube, maintains the same internal cross-section for adequate cooling, and works with the stock big grommet seal, Mercury part number 26-88397. The result is OEM-style cooling performance with upgraded material and long-term durability.
 
Part Options
Owners can choose the titanium tube that matches their mid-length and gearcase. The 12" mid Super Speed Master version mirrors Mercury 32-8476504 and is suited for SSM #4 and SSM #6 applications. The 15" mid SportMaster / TorqueMaster (ROS) version corresponds to 32-8476503 and is aimed at common 15" offshore and race mids. The 20" mid SportMaster / TorqueMaster (ROS) version replaces 32-8476502 and is used on standard 20" offshore EFI and performance mids.
 
Included Components
Each Titanium Big Water Tube assembly from Buckshot Racing #77 includes one titanium tube in the specified length and one new Big Grommet Seal, Mercury part number 26-88397. With the tube and seal supplied together, the assembly can be installed as a direct replacement where the original big copper water tube and grommet were used, without additional hardware or modification.
 
FAQ
In simple terms, titanium is chosen over copper because it is stronger, more corrosion-resistant, lighter, and less prone to damage during installation and service, while still allowing the tube to be manufactured with the exact OD/ID Mercury specified for parts 32-8476504, 32-8476503, and 32-8476502.
 
The Titanium Big Water Tube remains a precision part because the tubing is not an off-the-shelf size; it is custom-made to replicate the original Mercury dimensions so that it seals in the pump and midsection correctly, maintains proper cooling flow, and works with the 26-88397 grommet on high-performance Mercury and Mercury Racing outboards.
 
Includes one (1) Titanium Big Water Tube with one (1) new Big Grommet Seal part number 26-88397
 
For technical support, contact Mike Hill at +1-714-697-1716 or mike@buckshotracing77.com