Pulleys direct an applied force within linear and rotational systems of motion. The idler pulley is of the most important engine pulleys in the automotive system. Most vehicles have an idler pulley and a tensioner pulley. The tensioner pulley is designed with a bolt plate which mounts on the engine, the pulley which applies the tension, and the spring-loaded arm. The pulley has an inner bearing and outer ring.
Idler pulleys guide and tension the engine drive belts which are routed around the engine. The pulleys serve as smooth rotating points for the engine drive belts to loop around. The idler pulley is within a set of pulleys which regulate the belts connected the crankshaft. This connection is used to produce movement in many engine components. Since the energy generated by the engine is produced by linear motion from the pistons, the energy must be transmitted to the crankshaft in order to convert it to rotary motion. The major components influenced by the idler pulley include the air conditioner compressor, water pump, the power steering pump, and the alternator.
The idler pulley is a part of the belt system. Its design also includes a sheave or wheel that contains a groove which runs along the end. The idler puller is mounted between supports and holds on to a belt. The belt sits inside a groove and runs over a roller. The idler pulley wheel is rotated by the crankshaft movement, which turns the idler pulley belt. This movement enables speed, torque, and mechanical power transmission.
Fifty percent of tensioner failures are because of the idler pulley. Like any other parts, the idle pulley does become worn or damaged over time. As the part ages, it begins to slip. The wearing on the pulley is often the result of worn bearings. When the pulley wears down, symptoms arise to let you there is a problem. After a while or continuous high mileage, the pulley and belt both wear down to wear tension is reduced and the belt begins to slip.
Causes of Idler Pulley Noise
Belts, idlers, and tensioners should be replaced after 60,000 miles to protect the engine. When the idler pulley becomes worn out, it makes a squealing noise. You may hear the noise coming from the front assembly or the timing cover. There are a number of causes for the idler pulley to make noise. You should also pay attention to the type of noise the pulley makes. Here are the most common causes of idler pulley noise:
Old, worn out idler pulley – The idler pulley is continuously involved in the high powered action going on under your hood which means it becomes worn. The grooves no longer hold the belt firmly. The hardware inside the pulley begins to deteriorate. The hole in the middle of the idler pulley becomes larger, causing the pulley to move erratically. The first sign of a worn pulley is visible wear. You may be able to see scoring marks on the pulley which forms from the contact with the belts. At this point, the idler pulley noises are not so noticeable.
Idler pulley slippage – After the idler pulley has become worn, it begins to slip. The pulley binds and rubs against the engine belt. You will hear squealing noises as this goes on. The squealing noise will get worse the longer you drive with the slippage. Other engine belts will become damaged.
Worn spring-loaded arm – When the spring-loaded arm no longer provides the right amount of tension, there are problems.
Misaligned timing belt – The friction that occurs between the idler pulley and the belt wears the belt down. The pulley grooves eventually bottom out on the belt grooves, causing it to slip. When the timing belt is misaligned, the idler pulley can fail prematurely. Oftentimes, the idler pulley is not attached to the engine mounting correctly. The bearings for the tensioner may have become worn. This damage can also spread to the tensioner and the drive belt. When misalignment if found, the belts cannot be reused.
Idler pulley damage – If the pulley noise is ignored for a time, the pulley becomes damaged and may even break. The marks on the pully become large cracks that separate over time. The serpentine belt will also become damaged until it breaks. From here, the problems evolve into engine overheat and stalling. The squealing noise will be hard to miss.
Bearing failure – The ball bearings inside the idler pulley can go bad, which causes the idler pulley to make rumbling or clattering noises. The bad bearings also make a high pitched whine when you start the car.
You Treat Your Car Like Badly – Most vehicle owners understand that a vehicle must be inspected and serviced from time to time, as referred to as routine maintenance. For those who don’t, the likelihood of problems that cause their idler pulley to be noisy is extremely high. If the vehicle is not inspected routinely, small problems can escalate to major problems that are much more expensive to fix. This is also true for vehicles which sit for long periods of time.
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Symptoms of Bad Idler Pulley
Most people don’t bother to check the pulleys, belts, or tensioners when they check the oil and transmission fluid levels. If they did, they may see a few signs that the idler pulley is bad or about to go. Here are common symptoms that the idler pulley is going or gone:
Warning lights – The warning lights on your dash will activate to let you know something is wrong. If you hear the squeal of the pulley and a light is activate, these are your first clues to the problem. You can use an your OBD2 Scanner (view on Amazon) to see if the trouble codes have anything to do with the pulleys and belts that work together as part of the engine system.
Belt Travel – A very common symptom of a failing idler pulley is belt travel. This means the belt is moving about in ways that it shouldn’t. The belt may even shake or wobble and move from to side to side. This movement is proof that tension is not being maintained. Over time, this movement will eventually push the belt off of the pulley. The pulley will continue its rotation with no belt on it.
Power steering problems – The power steering feature in your car uses a hydraulic pump in order to pressurize the power steering fluid. The pressure is what makes it easier to turn the steering wheel. When the serpentine belt becomes cracked or broken the steering wheel will become stiff. The serpentine belt wears out naturally over time, or it can become loose or damaged.
The idler pulley is responsible for transferring engine power to the steering wheel pump. When the idler pulley malfunctions, it causes problems with the steering. The steering wheel may not move from side to side. Once the belt is worn or damaged, you must replace it.
Frozen pulley – When the bearings are bad, the pulley may freeze or become very hard to spin. This problem is called a frozen pulley. You will hear noise when this happens.
Squealing noise – The squealing noise that comes from a bad pulley is hard to miss. The noise is actually coming from the ball bearings inside the pulley. The sounds may include chattering or rumbling noises that put on like a much bigger problem than the pulley. . The more you drive with the problem, the more noticeable the squealing becomes.
Idler Pulley Noise from Timing Cover
If the noise you hear is coming from the timing, there are steps you take to fix the problem. Here are the steps to take if the noise you are hearing is coming from the timing cover:
1. Turn the car off.
2. Remove all that you must to access the timing belt.
3. Check the idler pulley for wear or damage.
4. Remove the timing belt.
5. Inspect the idler pulley and the tensioner pulley for any roughness when you rotate the bearing. The spin of the idler pulley and the tensioner pulley should be smooth and free. If there is any roughness, the bearings must be replaced.
What To Do About Idler Pulley Noise
Most people would rather not drive a car that is squealing. There are things you can do toward stopping the idler pulley squeaking. Here are some steps to take:
Use OBD2 Scanner – Use the OBD2 Scanner (view on Amazon) to pinpoint the problem with your idler pulley. The scanner will show you all of the trouble codes thrown for your vehicle. Some of the codes are specifically for the pulleys and belts.
Grease It – You can apply a light lubricant to the idler pulley to smooth out any kinks which are causing problems. You can even use a light household lubricant. Just drop a few drops of the lubricant inside the idler pulley.
Replace the idler pulley bracket – In many cases, the idler pulley is working just fine. It is the bracket that holds the idler pulley that may be warped or loose. There is a mounting bracket that holds the pulley securely to the engine. When the bracket is loose, the idler pulley has too much movement. Replacing the pulley bracket is a quick and easy job that save you lots of time and money down the road.
Replace the Idler Pulley – There comes a time when the troublemaker must go. Replacing your idler pulley will prevent ongoing problems that will eventually affect your engine. Replacing the pulley will not take much time. Follow these steps to replace the idler pulley:
1. Gather materials needed: torque wrench, replacement pulley, socket set and rachet.
2. Disconnect your battery to cut power to the engine.
3. Remove the drive belt. First, release the tension in the belt, then remove it.
4. (Remove the alternator bolt or the engine block bolt. If your pulley is connected to the alternator with a bolt, you must remove the bolt. If your pulley is attached to the engine block, loosen the engine block bolt.)
5. Push the alternator down to relieve some tension from the belt.
6. Remove the old idler pulley. Remove the retaining bolt, reach in and pull the idler pulley out. Keep everything that you remove.
7. Install the new idler pulley in the same placement as the old pulley you just removed.
8. Tighten the retaining bolt by hand.
9. Use the torque wrench to torque the pulley bolt to 40ft/lb.
10. Replace the drive belt.
11. Reconnect your battery.
Take your car to a mechanic – If you don’t have an OBD2 scanner, or you have no idea how to replace the idler pulley yourself, take your car to a local automotive professional. The car specialists will have a scanner and other computerized tools to perform diagnostics on your car. They will make sure that your idler pulley and belts are working properly. You can also prevent the problems from escalating by having regular maintenance checks performed on your car.
Remember safety first. Keeping the pulleys and belts in your car healthy and properly installed will prolong the life of your engine. It is not safe to drive a car with a bad idler pulley as any part of that system could snap or break at any time. Get your idler right and drive safely.