The connecting rod that links to the piston and the crankshaft in a car engine plays an important role in working to provide drive from the piston to the crankshaft where this power is converted into the rotational force required to make the wheels of the car move. The big end bearing is positioned at the big end of the connecting rod, the end that connects to the crankshaft. The big end bearing has a supportive role and functions to allow the rotating movement of the crankshaft and the crank rod journals/crank pins, while decreasing the amount of friction produced between the moving linked parts.

The movement of the pistons makes the crankshaft turn. The big end bearing coils around the crankshaft, securing the crankshaft in position, while enabling the rotating mechanism of the crankshaft. It is bolted to the connecting rod at the big end, with the smaller end of the connecting rod attaching to the piston. Essentially the big end bearing allows power from the piston to be transmitted from the connecting rod to the crankshaft.

The big end bearing doesn't normally come into direct contact with the crankshaft unless there's too little lubrication. The bearing consists of two metal shells that are floating on a layer of oil. If the lubrication levels are too low this can cause the bearing to knock against the crankshaft, which will cause the big end bearing to wear and eventually fail. It must be regularly lubricated.

If the big end bearing fails it severely affects the working of the engine as a whole. Often failure of this bearing indicates that there are likely to be further additional problems with other components. An indication that the big end bearing has failed is a rattling noise. A speedy replacement of this part could mean the difference between replacing just the big end bearing or having to replace the connecting rod, crankshaft and piston as well.

If there's a fault with the big end bearing a replacement big end baring should be purchased.