- One of the most common causes of screeching noises is a worn-out serpentine/drive belt.
- Other possible reasons for the screeching noises are worn-out wheel bearings, pilot bearings, or bushings.
- You can use either the water spray trick or the hand cleaner trick to determine if the serpentine/drive belt has worn out.
- Other engine noises include knocking, rattling, and clacking that warn about different problems.
The soft whirring or purring of the engine is a sound that almost all dedicated drivers love to hear. It means that all moving parts are in sync, and the passengers are in for a great ride. But what if your car is screeching rather than producing a low hum?
Any noise will typically be created by moving components, either in the engine compartment or in the wheel area. With that in mind, you can get an idea of where to look. If you’re hearing the noise sitting still, it won’t be a wheel or suspension related problem. If the noise is only present when the vehicle is moving, it’s more likely to be an issue in the wheel area.
If it only happens when you’re turning the wheels, there may be an issue with the power steering belt if it is a different belt from the rest of the belts; likewise, if you only hear the noise when you turn on the A/C. For example, some Chevy pickups will have a separate serpentine belt just for the A/C compressor.
Possible Reasons Why There’s a Loud Screeching Noise Coming from Your Car
A screeching noise coming from your engine compartment can typically be isolated with a few simple steps. Make sure to wear safety glasses and keep away from moving parts when checking your vehicle.
Here are some parts to check:
You Have a Broken or Worn-Out Serpentine/Drive Belt
If you hear a screeching noise right after starting your car but it goes away within a minute or so, the added alternator load right after starting the engine will reveal a belt that is loose or slipping.
There are a couple of factors to consider here. First, if you have v-belts, you can look and see if they’re highly polished and/or loose because v-belts don’t have automatic spring-loaded tensioners. But some serpentine belts don’t have automatic tensioners either. One example would be a Jeep Cherokee (87-2001). If the belt is a bit loose and needs tightening, it’ll squeal right after starting and/or when you operate the power steering all the way to the steering stops.
If the belt tensioner is an automatic or spring-loaded one, it can fail and allow the belt to run out of line, and that’ll cause a squealing problem. When replacing a tensioner, it’s always a good idea to choose a good brand. Avoid low-quality tensioners because they can fail after a short period of time, even a matter of weeks.
If the spring-loaded tensioner is bouncing and the belt is chirping, buy a good brand of belt and a good brand of tensioner and replace them both at the same time.
The belts and pulleys transmit power to certain components like the power steering pump, air conditioning system, and water pump. Ford calls the belt and pulley system the “Front End Accessory Drive” or F.E.A.D.
A broken belt can lead to a total engine breakdown.
For preventive maintenance, experts recommend replacing the serpentine belt anywhere between 50,000 and 60,000 miles. Replace the tensioner whenever you replace the belt if you can. Some tensioners can be difficult to replace, so be ready for that.
If you’re changing a serpentine belt, make sure you have a diagram of how the belt is supposed to be routed before you remove the belt, even if you have to draw one yourself. Sometimes, the belt routing will be on the radiator support cover along with the Vehicle Emission Control Information decal.
Tip for Diagnosing Bad Belts and Pulleys
If you believe one of the belts or pulleys is compromised, then remove the belt and put it on the ground away from the pulleys, then very briefly start the engine (less than 10 seconds) to see if the noise is still there.
If the noise isn’t there with the belt removed, shut the engine off and feel all the pulleys. Spin them to see if they spin freely or sound rough. See if they have lateral (side to side) play, etc.
The Alternator Isn’t Working as It Should
A defective serpentine belt can lead to a malfunctioning alternator. If the belt is slipping, the alternator won’t produce effectively. Components like the A/C compressor pulley bearing or the alternator can be the cause of squealing belts if their bearings are failing.
There’s a Worn-Out Wheel Bearing
A worn-out wheel bearing can produce a loud screeching noise from your car while you’re driving. That being said, a wheel bearing can make squealing sounds but usually won’t. Usually, a bad bearing will roar or rumble.
There’s a Worn-Out Pilot Bearing or Bushing
For many manual transmission vehicles, a pilot bearing or bushing helps support the transmission input shaft.
Over time, the bearing can wear out, and produce a screeching noise whenever the clutch pedal is depressed or released. The clutch release (throwout) bearing is usually the reason for a squealing when the clutch is depressed.
The noise tends to get louder when the speed difference between the engine and input shaft is at its greatest.
Diagnosing a Worn-Out Serpentine/Drive Belt at Home
Among other possible reasons, a defective drive belt is the most common cause of a loud screeching noise coming from your car.
While this might be the case, you shouldn’t rule out checking other parts that can create the same issue.
There are some methods you can try at home to identify whether or not the screeching noise is coming from the serpentine belt.
The water spray trick
Using this method involves spraying the belt with water while the engine is running. If the noise stops, it means the belt is slipping and causing the noise.
The hand cleaner trick
Sprinkle some grit-type hand cleaner or scouring powder onto the belt’s pulley side before cranking the engine.
If the noise is reduced, it can be confirmed that the problem is coming from the drive belt.
Keep in mind that even though these methods can be done at home, they require a basic understanding of engine components.
If you’re not familiar with what’s under your hood, you can always bring your vehicle to the nearest repair shop instead.
Other Types of Engine Noises and What They Mean
A loud screeching sound isn’t the only thing you should look out for whenever you’re out for a drive. Here are other types of engine noises that might require you to inspect your vehicle.
Bearings tend to produce knocking noises because of the stick-slip effect or excessive vehicle vibration.
If left unaddressed, worn-out bearings can damage the drive axle and steering assembly. They can also put the transmission and brake system components under a lot of stress, leading to premature wear on certain parts.
If you hear your engine producing a sound that’s similar to a baby’s rattle, it could mean that certain accessory mounts are loose, the harmonic balancer is broken, or the manifold heat control valve needs to be checked.
Loose spark plugs, accessory mounts, or rocker arms, a defective fuel pump, worn camshaft or rocker arm pedestal, and exhaust leaks are some of the most common reasons why your engine is producing clicking noises.
In some cases, disc brakes tend to produce squealing noises even when there’s nothing wrong with them. This is because of moving air.
To correct this issue, experts recommend cleaning the disc brake pads or installing anti-squeal shims and factory-type clips.
In addition, a squealing-scraping noise can be due to a brake rotor backing plate that is making contact with the rotor. This can be taken care of by gently bending the backing plate away from the rotor.
Keep in mind, however, that there are other reasons why your vehicle could produce squealing noises, so it’s best to have your vehicle checked by a professional once this happens.
A loud screeching noise from the engine is an issue that shouldn’t be taken lightly. There are several reasons why this could happen, so it’s best to have your vehicle checked by a trusted professional to identify the root cause.
Keep in mind that putting off repairs can lead to more complicated and costly issues down the road.
Lastly, there are also other types of engine noises that you should be mindful of. These noises could mean anything, ranging from loose mounting brackets and worn-out bearings to damaged or malfunctioning components.
Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.