Why Is My Car Making A Whistling Noise? - WhoCanFixMyCar

Whistling is an unusual noise for any car to make. Fortunately, most causes are easy to diagnose and reasonably cheap to repair. In this guide, we’ll cover all the different reasons your car might be whistling and what you can do to fix it.

In a nutshell: A whistling noise could be caused by dirty fuel injectors, a worn serpentine belt, broken window seals, a vacuum leak, low transmission fluid or a faulty radiator pressure cap.

My car makes a whistling noise while driving

There are two main explanations for a whistling noise while you're driving.

1. Dirty fuel injectors

This might be surprising, but clogged fuel injectors can cause a whistling noise. Typically, the sound won’t be as loud or strong as most of the other causes in this guide, but several other symptoms will accompany it. For example, the air-to-fuel ratio will be messed up, and the check engine light will come on.

Fuel injectors typically last between 60,000 and 100,000 miles. The best way to extend their lifespan is to change your fuel filter regularly; you could also add a cleaning agent to your fuel tank.

In this instance, take your car to a mechanic who can clean or replace your fuel injectors.

The average fuel injection system repair price on FixMyCar is £244.86.

Compare fuel injector replacement prices

2. Worn serpentine belt

The serpentine belt is a continuous belt used to drive multiple devices in your car’s engine, including the alternator and water pump. Learn more about how a car engine works here.

If the belt comes into contact with water from driving through a puddle or an interior fluid leak, it can start to make a whistling noise. The same applies if the belt becomes loose or damaged.

Like fuel injectors, the serpentine belt is hard-wearing, usually lasting between 60,000-100,000 miles. Signs that it's on its way out include:

• Squeaking, chirping or squealing from beneath the bonnet

• Check engine light

• Aircon stops working

• Power steering failure

You can perform a visual check to see if the belt might need replacing or tightening. 

Book a serpentine belt replacement

My car makes a whistling noise while accelerating

1. Vacuum leak

If the whistling sound in your car is most noticeable when you accelerate, your car might have a vacuum leak. The system that controls the airflow between the engine and the mass air flow sensor pushes air through a hose. This hose is susceptible to damage and may come loose, resulting in a whistling sound as air escapes.

A vacuum leak will make your car run less efficiently and only worsen with time, so although the repair might not seem urgent, it’s best to get it done sooner rather than later to avoid further damage and more significant expense.

Get your leak fixed

2. Worn window seals

If the whistling is coming from your windows and gets worse when you accelerate, this is probably due to worn out window seals. Constant exposure to heat and cold can speed up the deterioration of the sealant. Fortunately, it’s cheap and quick to replace it yourself. 

3. Low transmission fluid

Transmission fluid is a lubricant used in all vehicles. However, automatic transmission fluid is different from manual fluid because, in addition to reducing friction, it also acts as a hydraulic fluid in a much more complex system. 

Signs of low transmission fluid include:

• A burning smell

• Slipping gears

• Poor acceleration

• Leaks

• Check engine light

• Unusual noises such as whistling or whining

This guide provides advice about how to check car fluid levels. If your car's transmission fluid is too low, the whistling sound may be fixed by topping it up. However, there might be a leak somewhere in the system; the same thing will happen again unless you repair it.

Learn about diagnosing and fixing fluid leaks here.

The average price of a leak diagnosis booked through FixMyCar is £87.73.

Book a leak repair

My car makes a whistling noise after the engine is turned off

Faulty radiator pressure cap

A lot of drivers aren’t aware that the radiator pressure cap can actually make a whistling noise if it is damaged or comes loose. This part of your car serves an important purpose in removing excess heat from the coolant. 

Take your car to a garage to get the problem fixed so your coolant system can continue to function properly.

Get your radiator fixed

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