Identifying The Root Cause Of Engine Noise
17th December 2010
Identifying The Root Cause Of Engine Noise
Cars that were built a generation ago had a relatively simple design compared to those rolling off factory floors today. The engine, in particular, had fewer moving parts. Vehicles today are equipped with engines that are far more powerful and efficient. They are also much more complex, which means a greater number of things can go wrong.
In most cases, your vehicle will issue warning signs that indicate there is a problem with the engine. For example, the “check engine” light will usually go on, the assembly might misfire during acceleration, or a rough idle may become increasingly pronounced as the underlying issue worsens over time. Your engine might also make uncharacteristic sounds. When this happens, it is important to know how to troubleshoot the root cause, so you can address it. This article will offer a quick guide to doing so.
Tapping
If you hear tapping from your engine, there’s a good chance the oil level is low. Motor oil is essential to the assembly’s smooth operation because it provides lubrication for the moving parts. Without it, components will begin to make contact with each other.
One of the reasons this occurs is because of thermal expansion. As heat surrounding the engine rises, the metal from which the moving parts are designed expand. This reduces the amount of clearance that exists between them. If the oil level is low, there will be too little lubrication, and tapping can result. Replenish the oil level as soon as possible to avoid damage.
Knocking
This sound usually indicates that the fuel inside one or more cylinders is exploding out of sync with the spark generated by the spark plug. It is commonly called “spark knock,” and occurs when excess heat builds up in the cylinder. Because the timing of the cylinder’s valves and piston are thrown off, they collide. Both may become damaged.
Spark knock can occur for a number of reasons, including an excessive compression ratio in the cylinder and a malfunctioning exhaust gas recirculation (EGR) system. An overheating engine combined with low-octane fuel can also cause the problem.
You might also hear a deep knocking noise that sounds as if something is being struck by a hammer. This is typically caused by rod bearings that have become severely worn. When a bearing fails, your engine may sustain damage.
Squeaking
This noise can be generated by an assortment of small parts throughout the engine. A common cause is that one or more of the pulleys around which the timing belt moves has become loose. You can check the pulleys easily by turning the engine off, lifting the hood, and feeling for tension in the belt. If there is inadequate tension, check the individual pulleys, and replace the one that is about to fail.
If the tension in the timing belt is fine, check the pulleys near other components, such as the A/C’s compressor and alternator. When they come loose, they can make the same squeaking sound.
Shaking
At times, you may hear a knock-like shaking sound coming from the bottom part of the engine. This can be caused by something simple, such as carbon deposits having formed on one or more pistons. Such deposits often develop over time as a result of the combustion cycle. Unfortunately, fixing this problem requires taking the engine apart, a job that is usually expensive due to the labor involved.
Some of the noises described above may occur in the absence of an obvious reason. Avoid neglecting the noise. If you suspect there is a problem in your engine, have a technician perform a test. Even though doing so costs money, the investment is worthwhile since ignoring a strange sound can lead to a costly engine overhaul down the road.
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