Drivers warned squeaking noise could cost £100s - and WD-40 might make it worse

Motorists have been warned that not getting a squeaking sound checked could backfire, with petrol and diesel drivers at risk of hundreds of pounds worth of damage. According to motoring experts at Bumper, a high-pitched noise coming from under a car bonnet may be the sign of a broken fan belt.

A fan belt is one of the most important components in a vehicle with the vital tool responsible for powering everything from the car's alternator and cooling fan to power steering and air conditioning. However, over time this belt wears out and stretches with a squeaking or chirping noise one of the first signs that something is wrong. Experts have warned road users to never automatically reach for their WD-40 with issues likely to require further attention from a mechanic.

A spokesperson for Bumper said: "A squeaking noise from under the bonnet is often the first sign your fan belt is wearing out or has lost tension. It's a really common issue - but the wrong fix could end up costing you dearly.

"Fan belts are designed to run dry. If you spray any kind of lubricant on them, it can cause the belt to slip off the pulleys while the engine is running - and that can lead to engine overheating or damage to critical components."

"If your car uses an automatic tensioner and it's still squeaking, don't ignore it. Either the belt has had its day, or one of the components it drives - like the water pump or alternator - could be starting to fail."

In a blow to cash-strapped road users, replacing a worn fan belt could typically range from between £100 and £200.

The RAC has warned that labour charges can vary with road users likely to pay a premium if they have a luxury or performance vehicle. The breakdown experts warned the average belt can last for up to 100,000 miles, but this will also depend on the car's make, model and age.

Bumper adds that in some cases, the cost to repair the damage could be much higher - especially if the belt snaps or slips off while driving and leads to overheating.

Bumper added: "If you hear a high-pitched squeal when starting your car or turning the wheel, it's time to book it in - not reach for the WD-40. That sound might be annoying, but it's your car's way of telling you something's wrong."