Why Does My Car Hiss When I Accelerate?

Why Does My Car Hiss When I Accelerate?

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Car Hissing Sound When Accelerating: Causes and Solutions

When you’re driving your car and notice a strange hissing sound coming from under the bonnet as you accelerate, it can be concerning. The sound may vary in intensity, but it’s important not to ignore it. A hissing noise from your car’s engine while accelerating could indicate an underlying problem that needs to be addressed promptly.

In this article, we will explore the possible causes of a hissing sound when accelerating and provide you with solutions to resolve the issue. We will also answer some frequently asked questions to help you better understand this problem.

Common Causes of Hissing Sound When Accelerating

There are several potential causes for a hissing sound when you step on the accelerator. Let’s take a closer look at each one:

1. Vacuum Leak

A vacuum leak occurs when air enters the engine through an unintended pathway. This can create a hissing sound as the air escapes. The most common reasons for a vacuum leak include:

  • Cracked or damaged vacuum hoses
  • Loose or improperly installed intake manifold gasket
  • Faulty or worn-out throttle body gasket
  • Faulty brake booster or PCV valve

2. Exhaust Leak

An exhaust leak can also produce a hissing sound while accelerating. This occurs when there is a gap or hole in the exhaust system, allowing exhaust gases to escape before reaching the tailpipe. Common causes of an exhaust leak include:

  • Cracked or corroded exhaust manifold
  • Damaged or loose catalytic converter
  • Leaking exhaust pipe or muffler

3. Turbocharger Issues

If your car is equipped with a turbocharger, a hissing noise while accelerating could be a sign of turbocharger problems. The turbocharger uses exhaust gases to compress and force air into the engine, providing additional power. Potential issues with the turbocharger include:

  • Leaking or damaged turbocharger hoses
  • Faulty wastegate or blow-off valve
  • Turbocharger bearing failure

4. Coolant System Problem

A hissing sound from the engine compartment while accelerating can also indicate a coolant system issue. This can be caused by:

  • Leaking radiator or coolant hose
  • Faulty radiator cap
  • Air trapped in the cooling system
  • Overheating engine

5. Belt or Pulley Issues

Worn-out or misaligned belts and pulleys can create a hissing sound as they rub against other components. Possible causes include:

  • Loose or damaged belt
  • Faulty belt tensioner
  • Worn-out idler pulley or water pump pulley

How to Diagnose and Fix the Problem

Identifying the exact cause of the hissing sound can be challenging. However, here are some steps you can take to diagnose and fix the issue:

1. Visual Inspection

  • Inspect the vacuum hoses for cracks or damage.
  • Check the exhaust system for any visible gaps, holes, or corrosion.
  • Examine the turbocharger hoses for leaks or damage.
  • Inspect the coolant system for any signs of leaks or overheating.
  • Check the belts and pulleys for wear or misalignment.

2. Use a Diagnostic Tool

If the visual inspection doesn’t reveal any obvious issues, it may be necessary to use a diagnostic tool to scan for error codes and monitor sensor readings. This can help pinpoint the specific problem area.

3. Seek Professional Help

If you’re unable to identify the cause of the hissing sound or don’t have the necessary tools and expertise, it’s recommended to seek professional assistance. A qualified mechanic will be able to diagnose the issue accurately and provide the appropriate solution.


Q1: Why does my car make a hissing sound when I accelerate?

A: A hissing sound while accelerating can be caused by various factors, including vacuum leaks, exhaust leaks, turbocharger issues, coolant system problems, or belt and pulley issues.

Q2: Is a hissing sound while accelerating a serious problem?

A: While a hissing sound may not always indicate a serious problem, it’s essential to address it promptly to prevent potential damage to your car’s engine or other components.

Q3: Can I continue driving my car if it’s making a hissing sound?

A: It’s generally not recommended to continue driving your car if it’s making a hissing sound. It’s best to have it inspected by a professional to determine the cause and prevent any further damage.


A hissing sound when accelerating can be a sign of an underlying issue with your car’s engine or related systems. By understanding the potential causes, you can take the necessary steps to diagnose and fix the problem. Remember, it’s always best to seek professional help if you’re unsure or unable to address the issue yourself. Regular maintenance and prompt attention to any unusual sounds or symptoms will help keep your car running smoothly and ensure your safety on the road.

Car Accessories and Car Parts Store Alan Quine (Parr Lane) Ltd is Independently Owned With Over 35 Years Experience, We are rated “Excellent” on Trust Pilot. You can see a selection of our products here

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