As opposed to traditional solid pulleys, they allow the alternator to “free-wheel” or “overrun” every time the engine decelerates and, at the same time, dampen vibrations at the alternator . They come in two types: one-way clutches (OWCs) and overrunning alternator decouplers (OADs).
What is the function of pulley in alternator?
The alternator pulley functions as a cooling fan for the alternator and prevents overheating the interior wire, bearings, and brushes .
How does a alternator decoupler pulley work?
An OVERRUNNING ALTERNATOR DECOUPLERTM pulley helps “synchronize” the belt drive system for improved engine efficiency, reduced Noise/Vibration/Harshness (NVH) and increased component life . When an engine accelerates, the alternator's mass creates resistance against the belt.
How do I know if my alternator clutch pulley is bad?
If you ever hear growling or whining noises coming from under the hood, you could have alternator problems, which should be checked out by a professional ASAP. This growling or whining sound happens when the belt that turns the alternator's pulley becomes misaligned or rubs against the side of the pulley.
What is the pulley on the alternator called?
A serpentine belt is a single, continuous belt used to drive multiple peripheral devices in an automotive engine, such as an alternator, power steering pump, water pump, air conditioning compressor, air pump, etc.
How much is an alternator pulley?
There is an average cost for a drive belt idler pulley replacement. Labor costs are between 64 and $81 while parts are between $79 and $83 .
What is an overrunning alternator pulley?
The overrunning alternator pulley is a further development of the fixed belt pulley on the alternator . Thanks to its overrunning clutch, it damps the vibrations which are generated by cyclic irregularities in the crankshaft and also enables the engine speed to be reduced rapidly in the event of sudden load changes.
Can you replace just the pulley on an alternator?
In many cases it is possible to remove and install the overrunning alternator pulley while the alternator is still on the engine. The plastic protective cap cannot be re-used after it has been removed from the pulley. A replacement cap is supplied with the new part.
How do I check my overrunning alternator pulley?
Rev up the engine to approximately 2000-2500 revolutions per minute (rpm). Then shut it off and listen for a buzzing sound coming from the alternator. If you hear a short buzzing sound (1 to 5 seconds), the pulley's bearing may have worn out and the overrunning alternator pulley may require replacement.
Should an alternator pulley spin both ways?
The pulley should be able to rotate in the counter-clockwise direction even though the cooling fins are being held in place. If the pulley DOES NOT rotate in the counter clockwise direct and it is locked to the rotation of the alternator shaft then it has failed and must be replaced.
Does my alternator have a clutch?
An Overrunning Alternator Pulley (OAP) has a one-way clutch mechanism inside the hub that allows the belt to turn the alternator in one direction, but allows the alternator to free-wheel and spin at its own speed when the engine suddenly decelerates. ... Some replacement alternators come with pulleys and some do not.
Can you jump a car with a bad alternator?
While jumpstarting a vehicle with a bad alternator may technically be possible , do not leave jumper cables connected between vehicles longer than necessary as it can result in damage to sensitive electronics.
What does it sound like when the alternator is bad?
If you hear a small rattling or grinding sound when your engine is running, this could be caused by a loose bearing in your alternator. Conversely, if you hear a constant high whine while you are driving, this is usually a sign that your alternator is failing to distribute the necessary power throughout your vehicle.
Can you bypass the idler pulley?
Yes you probably can get a shorter belt and route it to bypass that pulley. The only thing is the belt will most likely slip every time the A/C compressor clutch is engaged.
What noise does a bad pulley make?
Squealing . When the engine is idling, a bad pulley may make a squealing sound. This is due to the bearings in the pulley going bad. The bearings may also make various other sounds such as clattering or even a rumbling sound, making the vehicle sound as if there was much more wrong than a bad pulley.
