Here's why:
* Accessibility: The rod bearings are located deep within the engine block, completely surrounded by other components. Getting to them, let alone working on them, with the engine in the car is extremely cramped and challenging. You'll lack the necessary space and angles to properly install and torque the bearings.
* Risk of Damage: The risk of damaging other engine components (e.g., crankshaft, connecting rods) during this process is significantly higher when the engine is still in the car. Any slight misalignment or dropped tool could lead to catastrophic damage.
* Proper Torque: Achieving the correct torque on the rod bolts is critical. This is incredibly difficult to do accurately without specialized tools and the ability to work freely around the engine. Incorrect torque will lead to premature bearing failure and engine damage.
* Oil Pan Removal: Even attempting partial access to the bearings necessitates removing the oil pan, which is a significant undertaking in itself, and often makes little difference to the overall challenge.
While you might find some videos or articles suggesting otherwise, those often showcase shortcuts or situations with extremely specialized tools, and those methods are not appropriate for most home mechanics. Attempting this without proper experience and tools is highly discouraged and likely to result in costly repairs or even a ruined engine. Pulling the engine is the accepted and far safer method.
