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Content
1. Possible causes for noises from the engine compartment
Unusual noises from the engine compartment worry every motorist. It is not uncommon for an unusual noise from the engine to indicate a serious problem with the car. In our guide, we explain what can cause the engine to clack, squeal or rattle. You will also find out how you can get to the bottom of the unusual noises yourself and what you should do to avoid engine damage.
If the engine in the car makes unusual noises, there are various possible causes. This can be a problem with the valve train or a problem with the auxiliary units. In the worst case, there may be defects in the pistons and cylinders that require quick action to prevent engine damage.
Not all noises from the engine area are also caused by the engine. Drivers should pay attention to whether the noise depends on the engine speed or the speed. However, unusual noises depending on the engine speed often indicate an engine problem.
Certain noises occur more frequently with some vehicle models or engines than with others. Model-specific noises are not uncommon. For example, certain BMW vehicles sometimes make howling noises after starting. These can be caused by defective pulleys in the power unit. Engines from the Volkswagen Group, on the other hand, are often plaged by a rattling noise that is caused by a stretched timing chain.
The drive unit itself is not always the cause of an unusual noise. The numerous auxiliary units of the engine can also make noises if they are not working optimally. These include the alternator and the power steering pump, but also the air conditioning compressor or the water pump. Worn drive belts of the auxiliary units, such as V-belts or V-ribbed belts, are also possible causes.
In some cases, an annoying noise sounds as if it is coming from the engine, but in reality the causes lie somewhere else entirely. For example, noises such as a rattling in neutral can also come from the clutch. The rattling of broken clutch springs then sounds as if the engine is rattling.
Sometimes there are loose parts on the car, such as a heat shield on the exhaust, that only vibrate at certain engine speeds and frequencies. This sometimes sounds as if the noise is coming from the engine. Defects in the gearbox or drive train can also be the cause of the noises.
If the car makes unusual noises, most drivers notice them immediately. Not all noises immediately indicate a defect. For example, a ticking engine with the bonnet open can also be caused by the normal ticking of the fuel injection. Other noises, however, occur far more frequently and should be given special attention.
Noises such as clattering, rattling or squeaking should be taken seriously in any car. There may be a serious problem with the engine that could eventually lead to engine failure. The cause of the noise must be investigated promptly. If you are not an experienced mechanic, you should visit a workshop as soon as possible.
If the engine makes a metallic clacking noise, it is not always possible to pinpoint the cause. Possible causes can be worn alternator bearings, but the noise can also come from inside the engine. In this case, the hydro tappets on the valves may be the cause.
These hydraulic tappets or valve lifters are mounted between the camshaft and the valve, where they regulate the valve clearance. The hydraulic tappets are particularly sensitive to fluctuations in the oil supply. If the clacking does not disappear shortly after starting the engine, the valves and hydraulic tappets should be examined more closely.
A frequently occurring noise in combustion engines is squeaking. The noise can occur continuously while driving or is only perceptible when accelerating. Squeaking noises are often caused by the V-belts. If the belts installed here are worn and in poor condition, they can no longer drive the auxiliary units such as the alternator properly and slip over the belt pulleys.
A rattling engine often occurs when there are problems with the timing chain. Often the timing chain has elongated with higher mileage, which is why the rattling noise can be heard. However, the tensioner of the timing chain may also be worn, so that it is no longer properly tensioned. Certain engine types are more prone to rattling noises than others.
Only expert car mechanics should carry out diagnoses or even repairs themselves if the engine makes an unusual noise. However, troubleshooting is never wrong. This not only helps to find the cause of the noise. The mechanic in the workshop can also isolate the cause of the fault more easily with this information.
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