One of the most serious breakdowns of the power unit is a sudden rotation of the connecting rod bearing. Such a malfunction is accompanied by a distinct metallic knock, a sharp drop in oil pressure, and significant wear on the crankshaft. The driver needs to understand not only how to act in the event of such a breakdown, but also the causes that led to it, in order to avoid encountering it again in the future.

Causes of connecting rod bearing rotation

Various factors can provoke the problem:
  1. Lack of lubrication. When engine oil stops reaching the rubbing parts, the metal begins to overheat, the bearing seizes to the crankshaft journal and rotates.
  2. Inappropriate oil. Using a lubricant with the wrong viscosity or using counterfeit products destroys the protective oil film.
  3. Violation of replacement intervals. If the oil and filter are not changed regularly, contaminants accumulate in the system, clogging the oil channels.
  4. Engine overheating. Critical temperature destroys the oil wedge, causing the bearing to rotate idle, without proper lubrication.
  5. General engine wear. Long-term operation of the unit without major repairs increases clearances, reduces oil pressure — and this leads to an accident.
To sum up, the main reason why the bearing rotates almost always lies in a malfunction of the lubrication system and excessive load on the engine.

First steps when the connecting rod bearing rotates

The main rule is to stop driving immediately. If a loud metallic knock is heard from the depths of the engine and the oil pressure has dropped sharply, you must immediately turn off the ignition. Continuing to drive in this mode can completely destroy the crankshaft. Further actions should be as follows:
  • Tow the car. Driving on your own with a characteristic knock risks ending in the unit seizing.
  • Disassemble the power unit. To assess the extent of the damage, you will have to remove the oil pan and the crankshaft.
  • Check the crankshaft. If scoring appears on the journal, it will need to be ground to a repair size or the shaft replaced entirely.
  • Install new connecting rod bearings. Only fresh parts are used — original or high-quality replacements.
  • Check the oil pump and channels. If the problem arose due to a lack of lubrication, this factor must be eliminated first.

Actual procedure for bearing rotation

The complexity of the repair depends on how badly the engine is damaged. If the damage is minor, you can get by with grinding the crankshaft and installing repair-size bearings. However, with severe wear, you will need to replace the crankshaft, connecting rod, or even the entire cylinder block. Experts advise:
  • not to skip scheduled oil and filter changes;
  • to fill only the viscosity recommended by the manufacturer;
  • to monitor the engine temperature and coolant level;
  • at the first signs of a drop in oil pressure, immediately check the system.

Summary

Now it is clear how to react if the connecting rod bearing has rotated, and where to start eliminating the breakdown. This malfunction is considered one of the most costly, but its causes are usually obvious: a lack of oil or its poor quality. Therefore, it is so important to understand why the bearing rotates and try not to allow the situation to repeat. If the problem does occur, there is only one way out — urgent repair with replacement of the bearings, checking the crankshaft and the entire oil system. Only this way will it be possible to restore the engine's performance and extend the service life of the car.