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What are the symptoms of a faulty belt tensioner pulley?

5 Answers
McHannah
07/24/25 9:19pm

The symptoms of a faulty belt tensioner pulley are as follows: 1. Difficulty starting. If the belt has not broken but is skipping teeth, it generally causes difficulty starting. After the engine barely starts, there may be symptoms such as poor acceleration and increased fuel consumption. If the belt breaks, it can lead to valve damage or even complete failure of the valve system. If the timing belt fails, the vehicle should be stopped immediately and towed to a repair shop for inspection. 2. Abnormal noise and slipping. The belts at the front of the engine include the water pump and fan belt, alternator belt, air conditioning compressor belt, and power steering pump belt, among others. Belt slipping noise is a sharp, piercing "squealing" sound, similar to a whistle, often occurring when the engine is first started, during acceleration, or when the air conditioning is turned on. Belt slipping may be due to insufficient belt tension or excessive wear or aging of the belt, which reduces the friction coefficient. To determine if the engine noise is caused by belt slipping, you can sprinkle a small amount of water on each belt after turning off the engine and then restart it. If the noise decreases or disappears, it indicates that the noise was caused by belt slipping. When there is belt slipping noise in the engine, the tension of each belt should be checked first. The standard tension for belts varies between different engines, but generally, when a force of 50-100N is applied vertically with the thumb to the middle of the belt between two pulleys, the deflection of the belt should be about 10mm. If the tension is too low, it should be adjusted. If the noise persists after adjustment, it indicates that the belt has aged and should be replaced.

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LeMadison
08/10/25 9:42am

As a driver who often operates older vehicles, I've experienced a faulty belt tensioner pulley. The symptoms include constant squeaking or chirping noises from the engine compartment, particularly louder during acceleration, resembling metal friction sounds. The belt may appear loose and can be easily moved with a light press, causing it to slip, deform, or even come off. This affects the alternator, making the battery light flicker and causing insufficient charging; the air conditioning compressor also stops working, resulting in no cool air inside the car, severely impacting driving comfort. I recommend stopping to check as soon as you hear unusual noises, otherwise, the belt will wear out faster, potentially damaging the water pump or steering system, leading to costly and time-consuming repairs.

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LaAustin
09/26/25 5:23am

During vehicle repairs, I noticed that typical signs of a failing tensioner pulley include persistent clicking or whirring bearing noises, noticeable belt bouncing, and insufficient tension. Worn tensioner pulley bearings can cause excessive belt slack, reduced transmission efficiency, unstable alternator voltage, and potential dashboard warning light illumination. The compressor belt may also dislocate, leading to AC failure. Regular inspection of belt condition is crucial; otherwise, replacing the belt and tensioner pulley in advance can save on repair costs.

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LeMiguel
09/26/25 5:24am

After years of modifying cars, I've found that symptoms of a bad tensioner are straightforward: increased engine noise, squeaking sounds during acceleration, belt vibration or slippage. Poor alternator performance leads to dimming lights and non-functional air conditioning. My go-to diagnostic method is simple: start the engine to listen for noises, check belt tension by hand – if it's too loose, the tensioner is the culprit. Don't ignore it to avoid damaging other components; replacing the tensioner will solve the problem.

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DelIker
11/09/25 7:26am

As a family user, I'm concerned about the safety risks of a faulty tensioner pulley. Symptoms include persistent abnormal noises accompanied by belt jumping, which may lead to insufficient charging and flickering headlights; a loose compressor belt can prevent cold air from coming out, making summer driving unbearable. During a long trip, the car shook severely, and after inspection, it was found to be caused by a worn tensioner pulley, costing money to repair the steering system. It's advised not to delay, as small issues can escalate and affect driving stability and comfort.

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