The center main bearing is one of the most critical wear components inside a Mercury V6 2-stroke powerhead. When you’re rebuilding a 2.4 Liter Mercury V6 or an early 2.0 Liter V6, replacing the center main bearing is a smart reliability move—especially on engines that have seen high hours, high RPM, or performance use.
The Mercury Center Main Bearing Kit 88903 (also listed as 88903T) is a widely referenced service kit used during crankshaft and bearing service on many classic Mercury V6 platforms.
This bearing kit is commonly associated with Mercury V6 horsepower families including 135 HP, 150 HP, 175 HP, 200 HP, 220 HP, and 225 HP, along with well-known performance model names such as XR2, XR4, and Bridgeport.
What the center main bearing does
On a Mercury V6 two-stroke, the crankshaft is supported by multiple main bearings. The center main carries heavy load because it supports crank stability through the middle of the rotating assembly where stress and vibration are highest. A healthy center main bearing helps maintain smooth rotation, stable clearances, and consistent crank alignment—important for both longevity and performance.
When a center main bearing is worn or damaged, it can allow unwanted movement that accelerates wear elsewhere. That’s why builders commonly replace it during any full teardown, especially if the engine had unknown history, metal contamination, overheat events, or high-RPM use.
Common reasons to replace the Mercury 88903 center main kit
Center main bearings are typically replaced during a rebuild because they’re inexpensive compared to the labor of tearing a V6 down again. If you’ve had water intrusion, debris in the crankcase, or a prior failure, a fresh center main bearing is part of restoring a clean baseline.
Even on running engines, the center main bearing is often replaced proactively during performance rebuilds on XR2/XR4/Bridgeport-era motors where the goal is long-term reliability.
Fits Mercury 2.4L and early 2.0L V6 2-strokes (common model naming)
This Center Main Bearing Kit (88903 / 88903T) is commonly listed for Mercury 2.4 Liter V6 and early 2.0 Liter V6 two-stroke outboards across popular horsepower categories. In the way owners typically search, that includes 135 HP, 150 HP, 175 HP, 200 HP, 220 HP, and 225 HP models, plus performance families like Mercury XR2, Mercury XR4, and Mercury Bridgeport.
Because Mercury produced multiple variations across years and markets, the safest confirmation is always by part number match in your parts diagram or build sheet: 18-1192, 22700, 307828, 310433, 67447, 775443, 777366, 88903, and 88903T.
Rebuild note: match the kit to your exact engine version
Mercury V6 engines evolved, especially across early 2.0L and 2.4L families. Before ordering, confirm you’re working with the correct crank/bearing arrangement for your exact block and year range. If your parts diagram references 88903 or 88903T (or cross lists it as 18-1192, 22700, 307828, 310433, 67447, 775443, or 777366), you’re in the correct center main bearing kit category.
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