What is the function of the idler pulley on cars?

The idler pulley is a common part that's found on the majority of the vehicles on the road. Its primary function is to provide tension and guide the engine drive belt. These belts wrap around the various parts of the engine such as the power steering pump, alternator, water pump etc...

1. What happens when an idler pulley goes bad?
2. Does a bad idler pulley affect performance?
3. What does an idler pulley sound like when it's going out?
4. What are the symptoms of a bad tensioner pulley?
5. Can I drive with a bad idler pulley?
6. Can a bad idler pulley cause alternator problems?
7. Can a bad pulley cause check engine light?
8. Can a bad idler pulley cause vibration?
9. What causes crankshaft pulley failure?
10. Is idler pulley same as tensioner?
11. How long do idler pulleys last?
12. Can a bad idler pulley cause misfire?
13. How do you know if your alternator pulley is bad?

What happens when an idler pulley goes bad?

Visual Clues of a Worn Idler Pulley

Such wear decreases tension that can cause significant belt slippage. If the pulley or bearing is noticeably damaged, cracking, breaking, seizing, or otherwise coming apart, it is an indication that it requires prompt replacement.

Does a bad idler pulley affect performance?

A broken or seized pulley can quickly lead to a torn belt, or in less serious cases, the belt falling off of the engine. An engine without a belt can quickly run into issues such as overheating and stalling, as it's the drive belt that allows the engine accessories to function.

What does an idler pulley sound like when it's going out?

Idler pulley slippage is likely to follow after it becomes worn out enough. This will cause the pulley to bind and then rub against the engine belt. As a result, there will be squealing noises coming from the engine area that will only get worse until the pulley is replaced.

What are the symptoms of a bad tensioner pulley?

If the tensioner is loose the belts may squeak or squeal, especially when the engine is first started. It is also possible for the tensioner pulley or bearing to wear out, in which case the vehicle will produce a grinding noise from the pulley.

Can I drive with a bad idler pulley?

So, how long can you drive with a bad idler pulley? The safety recommendation is not to drive the car at all and take it to a mechanic immediately. You should be concerned if the vehicle makes squeaking or rattling noises. The car can still run for months or break after a few days.

Can a bad idler pulley cause alternator problems?

Alternators are DRIVEN by the serpentine belt. All that happens when the belt disappears or pulleys seize is the alternator stops turning; there is NO possibility of damage to the alternator.

Can a bad pulley cause check engine light?

No, a pulley will not throw a Check Engine Light.

Can a bad idler pulley cause vibration?

Grinding noises – Grinding and rumbling noises are another common sign of tensioner or idler pulley failure, usually due to failing bearings. Excessive tensioner movement – Worn-out coil springs can also cause drive belt tensioners to loosen their grip on the drive belt, resulting in excessive vibration and rattling.

What causes crankshaft pulley failure?

Another way a pulley can fail is during the fitting process there has been an interruption with the assembly press or the friction bearing has been incorrectly pressed in. This can occur during the making and installation of the part with the vehicle.

Is idler pulley same as tensioner?

The primary distinction between tensioners and idler pulleys is the presence of an adjustable bolt. Tensioners are positioned on the bolt through mounting. Idler pulleys are not mounted to an adjustable bolt. ... However, if bearings fail, tensioner and idler pulleys both require replacement.

How long do idler pulleys last?

An idler pulley is expected to wear over time, and eventually the pulley will fail. Replacement intervals for idler pulleys vary, but are usually within the 50,000 to 100,000 mile range. Replacement often coincides with expected serpentine/accessory belt replacement periods.

Can a bad idler pulley cause misfire?

As far as I know, nothing that has anything to do with the idler pulley could cause the engine to misfire. It's just too much coincidence that something else would go bad immediately after this repair.

How do you know if your alternator 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.