Connecting-rod bearing
Lets a connecting rod rotate around its crankshaft journal.
Inside the big end of each connecting rod.
Bearing shells support cyclic combustion loads using an oil film supplied through the crankshaft.
A lubricated sleeve inside a moving hinge.
A loaded knock or metallic debris can suggest wear but does not identify the bearing by itself.
Usually condition-based rather than a routine replacement. Lubrication, overheating and the exact engine affect wear.
Internal-engine work is usually labor-intensive. Diagnosis and the engine code determine the repair scope.
Some BMW M engine discussions focus on rod bearings; maintenance advice must identify the actual engine and evidence.
BMW petrol and diesel engines; petrol-only systems are identified individually.