Symptoms Car’s Vacuum Leak & How To Fix?

The invention of the car’s vacuum is one of the most breakthrough technologies that help to shape the mechanism of modern cars as we used today.

Every car on the road needs to use vacuum to perform many functions.

To every car’s owner, the most common problems with their car’s vacuum system are leaks. Repairing car’s vacuum leaks is relatively cheap but finding what the causes of the leaks are is not that easy.

It may take quite a while for a professional mechanic to identify the problem. He has to look for every single part underneath the hood of your car to find out the cause of the problem.

You could help reduce the burden of this by taking note of the abnormalities that may happen to your car’s engine.

Why Vacuum Leak Are Bad?

The air/fuel ratio’s unbalance is one of the common results of a car’s vacuum leak. Air/ fuels ratio is the amount of air that needs to be present over the amount of a.

Because there is a leak in the engine, the air which is pushed inside the cylinders is not enough.

If the amount of air in the engine is not enough, combustion process will take a long time and a greater effort than usual. The power of your car’s engine will be affected.

Therefore, a vacuum leak needs to be spotted and corrected immediately to enhance the efficiency of your car’s engine as well as preventing your car from losing its power suddenly.

Reasons for a Vacuum Leak:

  • ​First, the connections among all vacuum lines are defected and loose.
  • Secondly, because all vacuum lines have been working for a long time under the heat of the underneath of your car’s hood, they all wear out and cracks appear in the surfaces, which could result in vacuum leak as well.
  • A gasket if it is malfunctioning could lead to vacuum leak

​Popular Symptoms Car's Vacumm Leak

​1. Idle Problems and Stalling

Idle problems could be that the idle speed is way too high. Sometimes when your car is idle, you can still feel the vibrating movements of your pedals or the steering wheels.

Sometimes, your car cannot be idle and stall instead. You encounter the problem of stalling when your car suddenly stops because it doesn’t get enough power.​

There are the symptoms of a vacuum leak because when an inappropriate amount of air is leaked out, it creates an unbalanced fuel/air mixture and make you car’s engine less powerful.

2. Difficulty Starting Engine

This is an extreme case of a vacuum leak. When the vacuum leak in your car gets worse, you may find it hard, or sometimes nearly impossible to turn on your car’s engine.

In order to turn on the ignition process, your car also needs the correct ratio of air and fuels in the engine.

In this case, there is not enough air in the cylinders and your car’s engine will not start because of this.​

3. Acceleration Problems

Acceleration problems are not always the case of a car’s vacuum leak but are still possibilities. Poor acceleration performance will affect the total time of a combustion process.

You will notice that the time to accelerate is not as quick as usual. This is because of the weak combustion process or unbalanced fuel/ air ratio, which is often too much. Your car is weaker; hence the slower acceleration process.​

4. Misfiring

You will also encounter misfiring if your car has a vacuum leak. A vacuum leak in your car will cause the inconsistency of the amount of air in the engine. Incorrect amount of air moving into the cylinder will cause the cylinder to misfire.

5. You hear a very loud noise

Sometimes you think your car is making the sound of a long “s”. If you hear the unusual and strange hissing noise in your car, you should first check where the noise is from.

If you think you hear it from where all the vacuum lines are situated or from the under hood, then it could probably is the sound of a vacuum leak.​

Strange noise coming from the sound of the pedal when you apply brakes could also indicate that there may be a vacuum leak in your car’s engine.

6. Check Engine Light button on your car is on

Another symptom which is very easy to recognize is that your Check Engine Light button is on. Although this symptom can be of any problems relating to the defects of your car’s engine, you still should take your car to a service center to have it checked for a vacuum leak.

How to Fix a Vacuum Leak in Your Car’s Engine by Yourself

​When you encounter all of the symptoms above and know for sure that there is a vacuum leak in your car, you can look for the area where the leak occurs and fix it. Finding the exact location will take a lot of your time and patience.

Here are the basic steps you could follow to find the vacuum leak and fix it, remember to wear personal protective equipment and be careful:

  • Step 1

​The first things to look for the vacuum leak are vacuum hoses. Search for any crack on the surface of all vacuum hose.

  • Step 2

​Check all the vacuum lines for any cracks and broken pieces.

  • Step 3

​If you find any crack on the surface of a vacuum hose or a vacuum line, then you should remove the broken one and replace the new one. New hose or line should be of high quality as these parts are easily damaged by the heat from the underneath hood.

  • Step 4

​If you can see no problems with vacuum hoses and lines, you can carry on the search by using a bottle of carburetor cleaner.

  • Step 5

In order to use the carburetor cleaner, you first need to turn on your car and set it to idle mode. After that, you can use the cleaner and spray a little bit neat the throttle bore gasket.

When you see the all the smoke that you sprayed has burnt and the idle speed of the car is increasing, then you should know that the problem lies in the gasket.​

  • Step 6

​If when all the smoke has burnt and your car’s idle speed is still very smooth, you should carry on to other parts of the engine, namely the intake manifold plenum and base gaskets. Observing the idle speed to see if the speed is increasing or stable.

  • Step 7

​If the idle speed of your car is still stable, you should move on to other external components such as EVAP control solenoids as well as other connectors while you are still checking the idle speed.

  • Step 8

​Continuing your search by spraying a large amount near the brake booster.

  • Step 9

Search for cracks and broken pieces in small vacuum tubes.​

  • Step 10

​If you still cannot find a vacuum leak after finishing all the tests below, you could try using a vacuum gauge. This machine is used to check for a vacuum leak externally.

You need to remove the vacuum tube from your car’s engine and plug it into the gauge. If the gauge cannot hold the tube properly, then it is where the vacuum leak occurs.

How An Expert Can Repair Your Car’s Vacuum Leak

​If you cannot find the leak yourself, you could take your car to a services center and have it check by a mechanic. He will help you to look for the areas where you cannot spot with just normal equipment.

Even though you provide the mechanic all the symptoms you notice, it is still hard to identify where the problem lies. Sometimes, some symptoms like acceleration problems are not because of your car’s vacuum leak but because of something else.

By taking notes of your knowledge about the current situations of your cars like the tendency to stall or strange noises you hear from your car will help mechanics to identify the areas of the problem quicker.

Inexperienced mechanics may take more time searching for the possible location of a leak; hence increasing the fixing time.

You should provide as much information as possible about your car. If you are able to give out the needed information, mechanics won’t take a lot of time searching for problems, which helps reduce your cost of repairing.


Overall, a vacuum leak can be fixed with a reasonable price and time if you are able to look for the problematic source right away.

You should consult an experienced mechanic, who can help you look for the vacuum leak quicker and fix the problem immediately and effectively.

You should never look down on a car’s vacuum leak as fixing it soon will help you maintain the performance of your car, your safety on the road as well as saving your money on fuels and further maintenance costs.​

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