How to Quiet Main Bearing Noise

Whether your engine is making knocking or rattling noises, you can quiet them by applying grease. While this may temporarily mask the problem, it is essential to get the bearing checked out. Here are some common causes and remedies for main bearing noises. Thickness of the oil, Condition monitoring, and adding grease will also help you determine if a bearing needs replacement. If you have no idea what is causing the noise, consider contacting a machine shop.

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Rattling or knocking sound

If you hear a rattling or knocking noise coming from your engine, it is likely to be a main bearing. The bearing faces have three different layers: a steel backing plate, a copper wedge, and a soft aluminum outer layer. If you hear this noise, it is a sign that your bearing has gone bad. If you are not sure, you can listen to your engine oil for the presence of a copper sheen.

A rattling or knocking sound coming from the engine can also be caused by a loose timing chain. The timing chain may be stretched or there may be a failed tensioner or guide. If the timing chain becomes loose, it may hit the timing cover and produce a loud clattering noise. Another rattling or knocking sound coming from the engine could be coming from the variable valve timing actuator. This component is at the center of the engine’s variable valve timing system, and failure of the actuator could cause the rattling or knocking sound.


If your car is making a grinding, rattling, or knocking noise every time it turns over, chances are it is a damaged or worn main bearing. The sound is most noticeable under heavy loads, but it can also occur at any engine speed. Symptoms of main bearing noise may include metallic shavings in the engine oil. If you have noticed this noise, it is time to have your main bearings replaced. You can use a stethoscope to locate the source of the noise.

Another symptom of a faulty main bearing is a knocking noise coming from the front of the vehicle. The noise might be accompanied by a warning light that indicates low oil pressure. You may also hear a humming noise when your car accelerates. The noise may be coming from the rod bearing or water pump. If the noise persists after you stop the engine and try a different one, it could be a faulty rod bearing.


Grease can mask a number of problems, including the presence of foreign particles. A lack of grease can cause the volume to drop below the necessary level before relubrication is required. Excessive grease, incompatible grease products, and mounting conditions can also cause problems. It is important to understand the causes of noisy bearings. A few tips to help you determine the cause of noise in your main bearings are listed below.

Dirt particles can wear down bearings. A thin layer of lubricating oil protects them from damage. Any impurities in the oil will erode the surface of the bearing and alter the clearance. Excessive oil in an engine can also cause noise and damage. A dirty engine is one of the most common causes of this problem. Make sure you clean the engine before reassembling it. Ensure that all parts of the engine are clean, especially the main bearing.

Thickness of oil

Increasing the thickness of engine oil is one way to quiet down main bearing noise. It will help your engine lubricate more efficiently, but thicker oil is more likely to starve the top end of your engine during cold starts and start-up conditions. That means your engine will be more prone to noise. The same goes for synthetic oil. Although synthetic oil is considered a better choice for the long-term health of your engine, it can also cause noise.

When choosing the right oil, it’s best to use the recommended viscosity. This viscosity is measured by weight and can be found on the oil label. Use the oil viscosity specified in the owner’s manual to silence engine noise. Deviating from this range can lead to engine problems, including noisy lifters. However, it’s worth it in the long run. So, how do you find the right oil for your engine?

Adding grease

Adding grease to quiet main bearing noise may mask the problem temporarily, but adding grease to a failing bearing will only delay the inevitable. If you suspect that the noise you hear is due to a bearing problem, it is important to perform bearing condition monitoring to determine how long the bearing is running without fail. By monitoring the condition of your bearings, you can determine when a relubrication is required and how often.

Adding grease to quiet main bearing noise is a relatively inexpensive process. In most cases, you will only need a grease gun once or twice. This is sufficient as grease guns are very rare. Adding grease to quiet main bearing noise is not necessary if your motor is running at full load. Just use two or three strokes of the grease gun to coat the entire bearing. You will notice a reduction in noise after the lubricant has sunk in.

Adding lubricant

Adding lubricant to the main bearing is an easy way to silence the noise, but it may not be the best solution. It only masks the problem, not addresses it. Adding lubricant to the main bearing may cause overheating by degrading the grease. This happens because excessive heat causes oxidation of the grease, resulting in the formation of dry crusty soap. Higher temperatures also weaken metal, causing early bearing failure. The lubricant also degrades as the metal heats up, and these factors should be carefully monitored.

In order to reduce noise, add lubricant to the main bearing and replace worn parts. It may be a good idea to check for the condition of the bearings periodically, and make necessary repairs. If they are noisy, they are most likely due to damaged raceways. These races allow the rolling elements to rattle and bounce, creating noise. Noise from bearings is usually caused by contamination. The shields and seals in these bearings may not be strong enough to prevent contamination, and this can occur in highly contaminated environments.