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Why does my car make a hissing noise?

Ellie Dyer-Brown, 1 year ago

5 min read

  • Advice
  • Maintenance
  • why
  • warning
Diagnose It Hissing Noise

WhoCanFixMyCar looks at some of the reasons why your car is making a hissing noise and what you can do to resolve it

While there are a huge number of noises your car can make which might indicate that something has gone wrong, hissing is one of the easiest to diagnose.

To help you understand what could be wrong with your vehicle, we’ve created a helpful guide that covers all the possible causes (and solutions), saving you money and stress.

Guide Contents:

I hear a hissing noise from my engine.

I hear a hissing noise when accelerating.

I hear a hissing noise when my air conditioning is on.


My engine is hissing

Engine overheating 

If you can hear hissing coming from the front of your car, it’s likely that the engine is overheating. Make sure you stop driving as soon as possible and allow your engine to cool down for at least fifteen minutes before investigating. 

If you can see steam coming from under the bonnet when you stop, it’s a good idea to leave this job to the professionals and get your car to a garage as soon as possible.


Exhaust leak

Exhaust Repair

If your exhaust manifold or pipe is damaged, this can also cause a hissing sound. Exhausts play an important role in guiding harmful gases away from the interior of the car, so you should get any leaks fixed as soon as you can for the sake of you and your passengers.


My car makes a hissing noise while accelerating

Damaged cooling system

Cooling system issues often cause hissing sounds, particularly if the problem is related to hoses. These are made of highly flexible rubber that is designed to withstand engine vibrations, high-pressure coolants, high temperatures and oils. 

However, over time these hoses do deteriorate, and when this happens it can lead to fluid leaks. Any kind of fluid leak in your vehicle is bad news, and you contact a mechanic as soon as possible. 

However, if you can hear a hissing sound it’s probably the sign of a vacuum leak, especially if your check engine warning light comes on and your car seems to be idling faster than usual. The best thing to do is book your car in with a garage so any hose damage can be repaired.


My car makes a hissing noise when the air conditioning is on

Leaking valve

The compressor within your air conditioning has a valve that makes a hissing noise if it starts leaking. Valves help with the pressurisation of the refrigerant gas, so you should book your car in to have its air conditioning system serviced. A hissing or shrieking indicates that the pressure inside the compressor is too high, and this is a serious situation. 

If your car is making a hissing noise, even if you think it might be nothing serious, you should always get it checked out by a professional.


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