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Deflection / Guide Pulley, timing belt
What are the signs of?
Any faults of this component directly affect the operation of the units it drives: the alternator, air conditioner compressor, hydraulic power steering pump, and cooling fan. For instance, the driver might notice that the car battery started charging slower. In this case, the battery warning light comes up or blinks on the dashboard. If your car has hydraulic power steering, with a bad serpentine belt you need much more effort than usual to turn the steering wheel. You can hear a specific squealing sound from under the bonnet when starting the engine and driving at high revs. During a visual inspection, you may notice cracks, abrasions, peeled off ribs, and traces of oil on the part.
Can a bad serpentine belt cause increased fuel consumption?
No, wear of this part doesn’t affect fuel consumption. Overtightened belt does cause increased lateral mechanical loads on the alternator and crankshaft. They need more energy for rotation, thus causing the engine to consume slightly more fuel. But this difference is so insignificant that is it almost impossible to notice it without using special precision measuring instruments.
Why does the serpentine belt squeal when it’s cold?
A squealing sound during engine start, especially when it is cold outside, is usually caused by the increase in the viscosity of the lubricant used in alternator bearings or pulleys and rollers of other auxiliary units. If the lubricant is solidified, turning the pulley requires more effort than usual. This causes the belt to slip producing a specific squealing noise. After some time, when all car units get warm, this sound disappears. Another cause of belt squealing right after the engine start is moisture that condenses between the belt and pulleys and evaporates after the engine warms up.
Is it possible to continue using the serpentine belt after detecting signs of failure?
A defective belt should be replaced immediately. Otherwise, it can snap during driving, which might make the car harder to steer, cause electrical equipment failure, and deplete the battery making it impossible to start the engine. Moreover, a torn serpentine belt is dangerous for the valvetrain: it may wind around the crankshaft pulley or other pulleys of this system. This may result in tearing of the toothed belt, breakdown of engine valves and cracking of the camshaft gear(s).
Can I replace a serpentine belt myself?
Replacement of the serpentine belt is quite a laborious procedure. However, if you follow tutorials from AUTODOC CLUB, you’ll be able to tackle it yourself. Remember that it is advisable to install new rollers together with the belt. Take a photo or draw the belt routing diagram before you start. And it is crucial to properly tension the belt when you’re done. For this, you might need special tools.
What causes a serpentine belt to break?
As a rule, the belt snaps because of it's excessive or uneven wear, or when the pulleys are misaligned, or when the bearings of the alternator and other auxiliary units are stuck. This problem occurs as well when the part was installed incorrectly, for example, upside-down or neglecting the vehicle manufacturer’s routing diagram. Ignoring the manufacturer’s recommendations to replace the pulleys together with the belt is also dangerous: a worn-out pulley has burrs on its surface that can damage the new belt. It is also important to keep the component properly tensioned.
What is the serpentine belt connected to?
Depending on vehicle construction and its trim level, this component may connect a different number of units. Usually, the belt is attached to the pulleys of alternator, air conditioner compressor, hydraulic power steering pump. Moreover, the system includes tensioner and idler pulleys. You can find a detailed diagram of belt routing in your vehicle manual.