When you service a Mercury lower unit water pump, a few small fasteners do the heavy lifting. The Mercury Water Pump Housing Stainless Steel Screw #14-8 x 2.25 inches is the dedicated screw that holds down the water pump housing by the water tube, helping keep the pump seated and the water tube aligned during assembly and operation.
This screw tightens with a 5/16" socket wrench and is commonly referenced by Mercury / Mercury Racing / Mariner / Quicksilver part numbers 10-96411 (often searched as 96411) and 8M0215009.
It’s a small part, but using the correct length and thread is important—especially on performance gearcases where consistent cooling and clean assembly matter.
What this screw does in the Mercury water pump assembly
This stainless screw secures the water pump housing near the water tube location, helping prevent housing movement and maintaining proper seating pressure. When everything is clamped correctly, the water tube connection stays consistent and the impeller can do its job.
When the screw is missing, corroded, stripped, or replaced with a “close enough” fastener, installation becomes harder and the chance of misalignment or loose hardware goes up.
OEM part numbers and sizing details
This fastener is commonly identified as a #14-8 x 2.25-inch stainless steel screw. In Mercury parts lookups you’ll see it listed as 10-96411, sometimes shortened to 96411, and in updated listings as 8M0215009. It uses a 5/16" socket drive for clean removal and installation during routine water pump and impeller service.
Fits legacy Mercury 2-stroke lower units and gearcase families
This screw fits a wide range of legacy 2-stroke Mercury lower units from the 2.0 Liter, 2.4 Liter, and 2.5 Liter era. It’s commonly associated with gearcase families, including the Sportmaster, Torquemaster, and Fleetmaster.
You’ll frequently see this hardware relevant to classic Mercury performance platforms and search terms such as 2.4L Bridgeport, 2.5L 260 EFI, 280 ROS, S3000, and 300 Drag, plus common horsepower groupings including 150 HP, 175 HP, 200 HP, 225 HP, 245 HP, 260 HP, 280 HP, and 300 HP setups using Sportmaster/Torquemaster/Fleetmaster-style lower units.
Why using the correct screw matters
Water pump service is one of those jobs where correct hardware saves time and prevents problems. Proper length and thread engagement help ensure the housing clamps correctly at the water tube location without bottoming out, stripping, or loosening under vibration. Replacing this screw is also smart any time the original is corroded, rounded, or questionable—especially if you’re already in the lower unit for an impeller.
Quick install note
Start the screw by hand to avoid cross-threading, then snug it evenly with the rest of the housing fasteners. A clean thread path and the correct screw length help keep the housing seated and the water tube aligned during reassembly.
For technical support, contact Mike Hill at +1-714-697-1716 or mike@buckshotracing77.com