Serpentine Belt Problems? 7 Most Common Problems & Solutions

The serpentine belt on your engine transfers the power from your engine’s crankshaft to the accessories attached to the engine. Most serpentine belts are rated to last around 50,000 miles and at the end of their life, they start to exhibit problems.

We’ll cover the most common problems with these belts and the simple solutions to fix them when they start to exhibit problems.

#1 – Your Serpentine Belt has Cracks and Glazing

Most of the most common problems with serpentine belts can be avoided with a simple visual check of their condition as they age.

New serpentine belts have one grooved side with ribbing and the other is smooth with writing. The grooved side will have between 4 and 10 ribs that align with grooves on each pulley for the accessories attached to the engine.

The grooves provide more surface area for the belt and pulley contact, and as they wear out, they will show signs of cracks forming in the ribbing.

Serpentine Belt Example

The side of the belt with text will glaze over or get shiny as the belt wears out. The text will start to wear off as the belt wears out. These smooth sides of the belt generally touch the pulleys that always keep proper tension on the belt.

How to Fix It

Knowing when to replace the belt is as simple as visually checking it for cracks and glazing.

The glazing over time isn’t a major concern, but it will eventually turn into fraying as the surface of the belt wears away from contact with the engine accessory pulleys.

The cracks will form over time, and the key is to replace the belt before the cracking becomes a significant problem. The cracks will eventually lead to chunks of the belt ribbing falling off.

When significant pieces of the belt are missing, or the belt starts to fray, it is close to failure and breakage.

If you don’t have a good understanding of when to replace the belt based on a visual inspection, make a point to have it replaced around 50,000 miles of use.

Most mechanic services check the belt condition when providing maintenance services such as oil changes. If they don’t mention the belt condition after their services, be sure to ask their expert opinion on the belt condition before leaving the facility.

#2 – Your Warning Lights on the Dash Indicate a Problem

The serpentine belt transfers power from the engine crankshaft to all accessories on the engine.

That includes:

  • The alternator that charges your car battery while you drive.
  • The power steering pump that assists when turning the steering wheel.
  • The air conditioning compressor to keep you cool.
  • And more.

If the belt has trouble turning any of the pulleys on the accessories, the warning lights on the dash may indicate a detected problem.

How to Fix It

The indicator lights tell you something is wrong, so it’s time to listen to what they are saying.

Start by checking the belt condition and make sure that it still turns all pullies on the engine accessories. If the belt is not turning one of the pullies, that is most likely the cause of the light turning on.

You may need to service or replace one of the accessories for the indicator light to turn off.

#3 – Your Serpentine Belt Makes Squealing Noises

Your serpentine belt should not make a lot of noise while the engine is running.

If it’s squealing or making a high-pitched sound, it’s likely slipping on one of the accessory pullies due to misalignment or the belt is indicating it is worn out. If a pulley has seized and will not turn, the belt may squeal as it tries to turn the pulley without success.

Read also, Why Are My Tires Squealing? 8 Reasons (Solved)

How to Fix It

All pullies on the engine accessories should turn freely and they should be aligned to prevent the serpentine belt from walking off the pullies. You can watch the engine run and listen for the source of the squealing.

One of the pullies may not be turning well due to a seized bearing, and that accessory should be repaired or replaced.

You can verify the alignment of the pullies with a long straight edge to ensure each pulley is in the same plane as the crankshaft pulley at the bottom of the engine. If one of the accessories is out of alignment, you need to return it to the same plane as the crankshaft and other accessories to remove the squealing.

#4 – You Have Heavy Steering

Most cars use a hydraulic power steering system that utilizes a pump driven by the engine accessory belt. If the steering in your car becomes heavy, and the steering wheel is difficult to turn, it may be a sign that your serpentine belt is not turning the pulley on the power steering pump.

How to Fix It

The serpentine belt turns the pulleys on every accessory, so first check that the belt is intact. If the belt has frayed or broken, it will not turn the pulley on the power steering pump, but it will also not power any other accessory.

If the belt is in good condition, the problem is with the power steering pump.

Next check that the power steering fluid level is full in the reservoir. The reservoir could be attached to the pump or remotely located. If the fluid level is low because of a leak, the system will not work well.

If there is a leak somewhere in the system, that needs to be fixed and the fluid level filled to the MAX mark on the reservoir.

#5 – Your Car’s Air Conditioning Stops Working

Your serpentine belt transfers power from the engine to the air conditioning compressor. When you turn on the A/C in your car, it should blow cold air. When it doesn’t, you may be having trouble with the belt and compressor.

How to Fix It

To start diagnosing the problem, check that the belt is in good condition, and it does actually turn the compressor pulley.

If the compressor pulley turns and does engage the compressor when the system is turned on, the Freon in the system could be low due to a leak.

A low Freon level will cause the A/C system to blow warm air instead of cold air. A professional mechanic can add dye to the system to trace a leak, fix the leak, and then refill the Freon.

#6 – Your Engine Overheats

The serpentine belt turns the pulley on the water pump. The water pump in turn circulates the coolant through the engine and out to the radiator to keep the engine cool.

If the belt doesn’t turn the pulley, the coolant sits stagnant in the engine and the engine will overheat.

How to Fix It

Your serpentine belt should turn the water pump pulley to circulate the coolant in the cooling system.

Without that circulation, the engine will overheat and can cause damage such as a blown head gasket. If the belt does turn the pulley, the problem could be low coolant in the system or a failed water pump.

First, check that the coolant is full in the overflow bottle or in the radiator. A low coolant level can cause overheating even if everything else works correctly.

A failed water pump may leak coolant or not circulate the coolant and cause the overheating. You’ll need to determine if the belt, the coolant, or the water pump is your cause for overheating and correct the issue.

#7 – Your Car Loses Power And Dies While Driving

The battery in your car stores the power that is used to start the engine.

The serpentine belt turns the pulley on the alternator that generates power to recharge the battery after the engine is started and run the electric accessories such as your audio system.

If the belt fails to turn the alternator pulley, your car will only use power from the battery to run the engine and accessories. The power will run out eventually and the car will stop running.

How to Fix It

Most cars will illuminate a light in the gauges if the alternator stops charging the battery. It is usually red in color and looks like a battery.

If that turns on, the belt may have failed and stopped turning the alternator pulley, the alternator has stopped generating power, or the battery has stopped storing power. Something has definitely happened to the electrical system.

Start by checking the belt condition and verify that is good without significant cracks or fraying. If the belt is in working condition, you can very if the alternator is generating power with the engine running by using a multimeter.

Measure the voltage between the battery terminals. It should be around 12 volts with the car turned off and between 13.4 and 14.4 volts with the engine running.

If the voltage doesn’t change at the battery with the engine running, the alternator has stopped generating power. If the battery shows zero voltage, the battery may be damaged and not hold power anymore.

Please also check out our article with 12 solutions for why your car won’t go above 20-30MPH.

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