King Engine Bearings MB5666SI0.25 Main Bearing Set Oversize Mercedes-Benz - 0.25mm M271

The King Engine Bearings MB5666SI0.25 is a precision-engineered main bearing set designed for Mercedes-Benz M271 C-Class engines. This oversize bearing set features a +0.25mm dimension for engines that have had their crankshaft journals ground or require oversized bearings for proper clearances.

Advanced Bi-Metal Silicon Construction:

These bearings utilize King's proprietary SI (Silicon) bi-metal material, which blends aluminum with 2.5-3% silicon for enhanced strength and durability. This lead-free bearing material is specifically engineered for medium-load engines, particularly those using nodular cast iron crankshafts, making it an ideal OE-replacement bearing solution.

Key Features:

• +0.25mm oversize for rebuilt or machined crankshafts
• Bi-metal aluminum-silicon alloy construction with fine micro-bore finish
• Lead-free environmentally friendly bearing material
• Complete main bearing set with 5 pairs included
• Precision matched wall tolerances to 0.0001 inch
• Designed specifically for Mercedes-Benz M271 C-Class engines
• Superior strength for medium-load applications
• Excellent compatibility with nodular cast iron crankshafts

Quality Assurance:

King Engine Bearings has been manufacturing premium engine bearings since 1960, specializing exclusively in bearing production. Every bearing undergoes rigorous quality control checkpoints throughout the manufacturing process to ensure only the highest quality components reach professional engine builders and enthusiasts. King bearings are trusted in demanding aviation and racing applications, with that same expertise applied to every aftermarket bearing they produce.

This bearing set is ideal for engine rebuilds where crankshaft machining has been performed or when standard size bearings no longer provide proper clearances. The silicon-enhanced aluminum alloy provides excellent wear resistance and load-bearing capability for reliable, long-lasting performance.