The Mercury Marine and Mercury Racing extra-thick 3/8-inch stainless steel, case-hardened washers are designed for use on powerhead studs, cylinder head bolts, and studs.
These are factory-correct OEM washers originally specified by Mercury for V6 outboards, making them the right choice for professional engine builders, racers, and serious performance enthusiasts who demand correct fitment and long-term reliability.
These OEM washers are used across a wide range of Mercury outboards, including 135, 150, 175, and 200 horsepower models such as the XR2, XR4, XR6, and XRi, as well as Mercury Racing engines, including the 225 Pro Max, 245 Carb, and 260 EFI, the 280 ROS, and the 300 Drag for Outboard Racing.
Built for Strength, Torque Accuracy, and Long-Term Reliability
Each washer is manufactured from stainless steel and case-hardened to resist deformation under high clamping loads. The extra-thick design helps maintain accurate torque readings and prevents washer collapse, a common issue in high-compression and racing powerheads where standard washers can distort over time.
The washer dimensions are critical to this performance. Each washer features a 3/8-inch inside diameter to correctly fit Mercury V6 studs and bolts, a 3/4-inch outside diameter for proper load distribution across the aluminum surface, and an extra-thick .105-inch profile for added strength and stability.
One side of the washer features a chamfered (beveled) edge, allowing it to seat properly against studs or bolts while protecting aluminum cylinder heads during installation and removal. This design detail promotes consistent clamping force and contributes to the long-term durability of surrounding aluminum components.
Mercury V6 Engine Compatibility from 1976 Through 2018
These OEM washers fit all Mercury V6 outboards produced between 1976 and 2018, including 2.0-liter, 2.4-liter, and 2.5-liter engine families. They are compatible with both powerhead studs and cylinder head bolts and work across common Mercury midsection configurations, including 12-inch racing, 15-inch ROS, 20-inch fishing and bass, and 25-inch XL setups.
This broad compatibility makes them a dependable choice for restorations, performance rebuilds, and race-ready engine assemblies.
OEM Mercury and Mercury Racing Part Number Cross-References
These washers directly cross-reference multiple OEM Mercury and Mercury Racing part numbers, including 12-70833, 12-45175, 12-F1778, 2550W23059, F1778, 45175, 70833, 856774, 12-856774, and 8M0214963. Using OEM hardware ensures correct fitment, proper material specification, and eliminates guesswork during assembly.
Washer Pack Sizes Available for Any Build
To match different service and build requirements, these OEM washers are sold in 8-pack, 10-pack, and 24-pack quantities.
This allows you to choose the correct amount for partial service work, complete cylinder head or stud applications, or multiple engine builds without overbuying or running short during assembly.
Why Extra-Thick Washers Matter in Mercury V6 Engines
Using factory-correct, extra-thick washers plays a critical role in maintaining consistent torque values, protecting aluminum cylinder heads, and ensuring long-term engine reliability. In high-performance, racing, or freshly rebuilt Mercury V6 engines, OEM hardware helps eliminate weak points that can lead to uneven clamping force or head gasket failure.
Whether you’re rebuilding a stock fishing motor, refreshing an XR-series engine, or assembling a Mercury Racing drag or offshore powerhead, these OEM Mercury V6 washers deliver proven fitment, strength, and confidence trusted by experienced builders.
Contact Mike at 714-697-1716 or mike@buckshotracing77.com for technical support.