Causes and remedy for alternator belt whistling
If you are driving your car and suddenly hear the alternator belt whistling, – don't be alarmed – it's not always a «verdict». To find out why your alternator belt is whistling, read our article.
First, let's look at what the belt is.
Stypes of alternator belt
Today there are three types of belts that are installed on generators: toothed, V-belt, poly-V-belt. Each brand of car has its own type of belt. Which one is suitable for you – is indicated in the manual of the car, as well as on the Internet.
The task of the alternator belt – transfer of rotation (torque) from the crankshaft to the rotor of the auto-generator, thanks to which the latter produces electricity and transmits it to consumers, which includes the battery. This belt is put on the pulleys of the crankshaft and the car generator, and, since it plays a very important role in the operation of the car, must always be serviceable and properly tensioned. A starter and alternator test bench manufactured by MSG equipment can help ensure that the alternator is working correctly.
How to eliminate alternator belt whistling
Let's look at the causes of the annoying sound coming from the belt, as well as options for eliminating it.
How to fix an alternator belt whistle
An alternator belt whistle on a cold engine
An alternator belt whistle when starting an unheated engine is often the result of belt slippage. The torque transmitted from the crankshaft is insufficient to spin the alternator pulley.
Causes:
- The generator bearings (not the belt) are not properly lubricated. In the cold season, it is worth considering that the density of lubricants becomes higher, due to which the generator pulley in the conditions of a cold start of the engine is not able to spin properly, until the engine warms up to the required temperature.
«What to lubricate the alternator belt in winter?"», – you ask. Lubricate the bearings with frost-resistant grease, but the belt itself – don't. In case of coarsening, it can be treated with a special aerosol softening rubber.
- Insufficient tension of the alternator belt. Similar to the above, when the engine is not warmed up, the belt with insufficient tension is not able to take normal acceleration on the pulley, and its unstable operation will be accompanied by a characteristic whistle. It will also occur if the length of the belt is incorrectly matched or if it is stretched due to prolonged use.
The solution – adjusting the alternator belt tension, which we'll discuss in detail below.
How to check the alternator belt tension
When you don't have a service book handy, a folk method of checking alternator belt tension helps. Take a section of belt between the alternator pulley and the crankshaft and twist it round its axis. If the twist angles less than 90º, the alternator belt is tensioned correctly.
What can result from improper alternator belt tension
If the alternator belt is loose – this can lead to the discharge of the battery; if it is over-tensioned – the belt will break and important parts of the car will be damaged.
If the alternator belt is loose – this can lead to the breakage of important parts of the car.
Important information!The whistling of the autogenerator belt at cold start can also appear in the case of jammed pulley. You can check this yourself by turning the pulley of the generator. If it does not yield to the applied force and stands still, a thorough repair or complete replacement of the alternator is required at a car repair shop. Learn more about generator and starter diagnostics and repair business.
Belt whistling under load
A whistling or squealing alternator belt under load can occur for several reasons:
- Lubricating fluids on the pulley or on the belt itself. – Remove traces of service oil.
- Belt tension is incorrect. – Adjust the tension.
- Autogenerator bearing failure. – Replace worn bearing.
- The alternator and crankshaft pulleys are misaligned. – Align the pulleys on a single guide.
Now you know the causes of alternator belt whistling and how to fix them.
