How Long Can You Drive With A Bad Idler Pulley?

Idler pulleys do the function of guiding and tensioning the engine drive belts. The drive belts pass through various engine components including the power steering pump, water pump, alternator, and AC compressor. The pulleys create some rotating points for the belts to stay on their designated loop. How bad can it be when any of these pulleys are damaged or broken? How long can you drive with a bad idler pulley?

Most engines have one idler and one tensioner pulley, but some units may have more than one idler pulleys. These parts will wear out over time and have to be replaced.

The Symptoms Of A Bad Idler Pulley

Before knowing the danger of a worn-out idler pulley, you should know about the symptoms to detect a bad pulley in the first place. You should be worried if these warning signs occur:

1. Squealing Noise

The engine belts will make a squealing noise when there is an issue with the idler pulley. It could be a worn-out surface or a pulley that gets stuck. The lack of motion from the pulley makes the engine belt rub against its surface and yield the squealing sound.

bad idler pulley
A bad pulley will create a squeaking noise (Photo Source: gettyimages)


2. Worn Out Surface

If you spot the squeaking noise, you should check the idler pulley for any visible wear. Due to the continuous rotation, the component is supposed to deteriorate over time. Be prepared to change the pulley if you see scoring marks on its surface. It will ultimately lose tension and cause belt slipping.

3. Damaged Pulley Or Bearing

This is even more visible than the worn-out surface. Sometimes, the pulley or bearing wears out to the point of cracking or breaking apart. This affects the belt’s rotation and creates problems with engine functions. It can also cause the belt to fall off of its slot, leading to an overheated or stalled engine.

How Long Can You Drive With A Bad Idler Pulley?

The idler pulley has a crucial part in the overall engine operation. The proper functions of all engine components partly depend on drive belts and pulleys. Take the vehicle to a repair shop if you suspect that the pulley is having an issue. Remember that need replacement at regular intervals, especially in high mileage cars.

A damaged pulley can cause the drive or serpentine belt to dislodge. If that happens, all components that derive power from that belt will stop functioning. On most vehicles, these parts include the alternator, water pump, power steering, air conditioning system, and different exhaust components.

drive with a bad idler pulley
Change the pulley when it is damaged (Photo Source: newcougar)

This could be dangerous. For example, a non-operational power steering could cause an accident. The engine can get overheated and then damaged due to a dysfunctional water pump.

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. You should not take the risk as it could lead to engine failure if not taken immediate steps.