2011 Mazda MX-5 Miata - Connecting Rod Bearings

What are Connecting Rod Bearings?

The connecting rod bearing is a type of engine bearing found at the junction of the connecting rod or piston rod and the crankshaft. Connecting rod bearings provide a smooth surface to interface with the crankshaft journal, allowing for smooth articulation of the piston through the path of its stroke. Also called rod bearings or engine rod bearings, the rod bearings are typically split into two halves, one of which presses into the connecting rod and the other in the rod cap. Age, low oil levels, or excessive heat can cause your connecting rod bearings to wear and allow for play or looseness around the crankshaft. This can also lead to crankshaft damage if not addressed promptly, and it is usually a good idea when replacing connecting rod bearings to also have the crankshaft polished or ground at a machine shop to ensure a long-lasting repair. This can change the size of the crankshaft journals, which may require oversized main and rod bearings to ensure appropriate tolerance and fitment. Signs of a bad connecting rod bearing include a knocking sound on startup or clunking noises on acceleration from low in the engine, low oil pressure, or the Check Engine light may activate. These symptoms could also be caused by low oil levels, coolant in your oil, contaminant or sludge buildup, or main bearing failure, so be sure to inspect the engine during your rebuild before completing your diagnosis or repairs. If left unrepaired, the connecting rod bearing may seize to the crankshaft, which can break the connecting rod and destroy the engine. This will typically require a full engine rebuild, and this is a good opportunity to also replace the main bearings, piston rings, and more to ensure the longest engine life. Regular engine maintenance, including oil changes and monitoring oil pressure, can help to preserve the condition of the connecting rod bearings and prevent potential engine issues caused by bearing wear. If you're rebuilding your engine or replacing your connecting rods, pick up a set of connecting rod bearings from O'Reilly Auto Parts, where you can also find all the parts for a complete engine rebuild.