A serpentine belt is a vital component of a car’s engine, driving many parts of the vehicle, such as the water pump, alternator, and air conditioning.
Over time, the belt can wear down, crack or even break completely and become loose in the engine bay. This will cause an immediate breakdown and may cause costly engine damage.
This car maintenance guide to serpentine belt replacement explains all you need to know about how it works, warning signs there may be an issue, and how much it will cost.
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What is a serpentine belt?
The serpentine belt is a long, continuous rubber belt that is found at the front or side of the car’s engine bay.
It is threaded around a series of pulleys, from the main engine crankshaft pulley to pulleys on other key components. So when the engine is running, all the pulleys will run at the same time.
Serpentine belt components include:
- Alternator
- Power steering pump
- Air conditioning compressor
- Water pump
- Cooling fans and coolant pumps
- Hydraulic suspension pumps
- Vacuum pumps in braking systems
Most modern serpentine belts are made from highly durable rubber compounds that can deal with constant movement, as well as intense heat and tension.
The belt runs through a system of pulleys and is kept tight through a belt tensioner. This is designed to prevent belt slippage and ensure the components are running at their correct speeds.
A worn or damaged belt can quickly lead to performance problems, including engine overheating, steering problems, charging faults and usually accompanied by warning lights on the dashboard.
Is it safe to drive a car with a bad serpentine belt?
No, it is not safe to drive with a damaged serpentine belt. This is because it is crucial for the alternator, power steering, water pump, and air conditioning.
It can lead to a sudden breakdown from the engine overheating and battery failure.
The best course of action is to have it replaced immediately.
How much does it cost to replace serpentine belt?
According to the latest data, the average replacement cost for a serpentine belt is anywhere from £80 to over £250.
However, there are many factors that can impact the final cost, including make, model, age, and condition of the connected components – as well as the work that needs to be carried out.
More premium models can lead to replacement cost of more than £300.
Source: RAC
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When should you replace the serpentine belt?
Most manufacturers recommend that you should replace the serpentine belt every 60,000 to 100,000 miles – although the exact interval can depend on the vehicle and driving conditions – as well as the level of servicing.
Some modern drive belts can last longer, but regular checks are vital.
If the engine is exposed to extreme temperatures and pressure, then it can lead to early failure.
Oil contamination from leaks etc. can also damage the belt, so it is important to check if there are any signs.
Common serpentine belt problems
Although they are generally one of the most reliable car parts, serpentine belts have some common issues to look out for.
- Cracking or fraying along the belt surface
- Belt slipping from the pulley and tensioner
- Squealing sound during engine start up
- Belt is visibly shiny
If you believe there is an issue with your serpentine belt, then it is best to take your vehicle to a trusted local garage. For any other issues, call a mobile mechanic.
Other belts in a car
There are other belts that may be found in some vehicles:
Fan belt – Often found in older vehicles, it is an earlier form of drive belt and is used to power the cooling fan and alternator. Modern vehicles use serpentine belts instead.
Timing belt – This usually sits inside the engine or engine cover and synchronises the crankshaft and the camshaft, so valves open and close at the correct time.
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