通用大Recall

https://www.cbsnews.com/news/gm-recall-escalade-silverado-suburban-sierra-engine-failure-risk/

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manufacturing defects. Investigations found that connecting rod bearings were damaged by sediment, and that crankshaft dimensions and surface finish were out of specification—both pointing to quality control or supplier manufacturing lapses. The SunautoevolutionAP NewsCarscoops

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Root Cause Overview

1. Connecting Rod Bearing Damage by Sediment

   • Issue: Abrasive particles (sediment) contaminated the engine oil system.

   • Effect: These contaminants wore down or damaged the connecting rod bearings, which are crucial for smooth engine operation.

   • Impact: Bearing damage leads to increased friction, overheating, and potential engine seizure or catastrophic failure.

2. Crankshaft Manufacturing Defects

   • Out-of-Spec Dimensions: The crankshaft journals (the parts the bearings ride on) were machined outside the allowed tolerances—meaning their size or shape wasn't within acceptable limits.

   • Surface Finish Deficiency: Some crankshafts had rough or improperly finished surfaces—instead of being smooth, they had microscopic ridges or imperfections.

   • Effect: This accelerates wear on the connecting rod bearings and can disrupt oil film—which is vital for bearing lubrication and heat dissipation.