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Difficulty: MediumLubrication System

In an automotive engine with a full-pressure lubrication system, how do the connecting rod bearings receive pressurized motor oil?

  1. Through internal passages drilled through the crankshaft from the main bearing journalsAnswer
  2. B
    By relying solely on crankshaft counterweights splashing fluid upward from the oil pan
  3. C
    Through coolant passages surrounding the cylinder walls and combustion chambers
  4. D
    By blending motor oil directly into the incoming air-fuel charge during the intake stroke

Answer

Pressurized motor oil reaches the connecting rod bearings through internal passages drilled through the crankshaft from the main bearing journals.
In a full-pressure lubrication system, the oil pump delivers pressurized oil to the main oil gallery in the engine block. The oil flows into the main bearing saddles through holes in the upper bearing shells. From the main journals, the oil travels through diagonal passages drilled internally through the crankshaft to lubricate the connecting rod journals and bearings.

Step-by-Step Solution

1
Identify the primary oil distribution pathway in a modern full-pressure automotive engine.
The oil pump forces fluid through the main oil gallery in the cylinder block directly to the crankshaft main bearings.
Main bearings sit directly in the engine block saddles where pressurized oil galleries are located.
2
Trace the path from the stationary block saddles to the rotating connecting rod journals.
Holes drilled at an angle through the crankshaft webs connect each main journal to its adjacent connecting rod journal.
Connecting rod journals rotate in an orbit and cannot receive oil directly from stationary engine block galleries.

Key Concept

Crankshaft oil flow pathways in a full-pressure automotive lubrication system
Estimated Time:1m 0s
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Topics

Lubrication System

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