The crankshaft bearing is one of the wear components of a vehicle. It wears down over time. That is why it is important for drivers to follow the manufacturer’s recommended oil change intervals and belt replacements. You will know that it has become faulty when you experience symptoms of a bad crankshaft bearing that include knocking noises coming from the engine, metal shavings in the oil, low oil pressure, and crankshaft bearing noises.
The crankshaft is the one that converts the linear motion of the pistons into the rotational movement needed to move a vehicle. The crankshaft does this by swinging around and pushing the piston back up the cylinder when the fuel combustion shoots the piston right down the cylinder.
The crankshaft bearing is the one that supports the crankshaft by providing its rotation under inertia forces produced by shaft components and swinging forces transferred by the connecting rod. It helps lessen the friction between the spinning crankshaft and the stationary engine block which is one of the reasons why crankshaft bearings become faulty over time. The task it has to do is the main reason the bearings sustain damage which could trigger the symptoms of a bad crankshaft bearing.
The crankshaft bearings are generally made to be durable but normal wear and tear can happen and it could happen faster if the recommended car maintenance and service schedule are not followed. If your crankshaft bearings fail, your vehicle will most likely have a catastrophic engine failure.
Knocking noises coming from the engine is one of the common symptoms of a bad crankshaft bearing. Drivers usually refer to this as a rod knock which sounds like a consistent hammering that increases as the RPM does. This can occur when the crankshaft bearing has worn out that causes excess clearances. Rod knocks can happen when the rod big ends hit against the crankshaft at the top and the bottom of the piston stroke.
A low or reduced oil pressure is an early symptom of a bad crankshaft bearing. You will usually notice it when you first start your car. Sometimes, a worn bearing can also set off the check engine light to illuminate intermittently depending on the severity of the problem.
Worn bearings can lead to having excess clearances between the bearings that can trigger an oil pressure leak. It usually occurs when your vehicle is at low RPM where the pump is spinning the slowest. Although low oil pressure can be caused by a lot of issues from other car components, it is also one of the symptoms of a bad crankshaft bearing.
If you check your oil using a dipstick and you notice metal, silvery shavings or aluminum dust in it, it is an indication that your bearings have worn out. You will know if what you found in the oil is caused by a worn bearing if the aluminum shavings look like dust or is powder-fine. If you see splinters or strings of aluminum stuck in the dipstick, it means that it is not caused by normal wear and tear but from overheating or running out of oil. This could mean that your bearings have already failed or are starting to fail.
It is always a good habit to check the oil filter after every oil change to see if there is any aluminum dust or shavings present that could indicate a problem with the bearings. A good mechanic usually does this and cuts the top off the oil filter after doing the oil change. If you are doing the oil change yourself, it is important to check the filters too.
A lot of crankshaft bearings have three layers that include an aluminum outer layer, a copper layer in the middle, and a steel backing plate. These kinds of bearings use copper that is known to be a softer but smoother metal compared to aluminum. This is done to give an extra protective layer before the bearing wears down to the steel or before it completely fails.
This problem is caused by low oil pressure that can potentially damage the bearing surfaces and the crankshaft itself. The crankshaft bearing noise can be heard as a rumbling or thumping sound that seems to be coming somewhere deep in the engine when you are accelerating.
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