Symptoms of a Boost Leak & The Causes

turbo boost leak

Are your ‘check engine light‘ flashing on your dashboard and the engine’s power suddenly feels reduced?

Then your car engine might have put itself into Limp-Mode and the issue should be fixed as fast as possible. Boost leaks can damage your turbocharger and your engine, which may result in even higher repair costs.

In this article, you will get all the information on how to detect and repair a boost leak and finally get your car’s full performance back. Let’s begin!

Boost Leak Information

A boost leak is a type of air leak that happens in the intake path just before the engine cylinders. It is basically a loose clamp that cannot handle the pressure from the boost.

Engines that have turbo are more prone to a boost/intake leak as compared to non-turbo engines, because of the added numbers of pipes and hoses joining the turbo with the engine equipment and the pressure that a turbo gives. These hoses and pipes are directly exposed to the heat inside an engine bay, which can cause cracks in them and lead to leaks.

Sometimes, leaks in a pipe can happen due to a loose engine mount, which can twist a pipe simply with torque. Although, loss of power is not harmful – except if you are in a race – it can become harmful if neglected for a long time.

Ignoring a boost leak will eventually reduce your turbo’s life and in turn the car engine’s life. Understanding the workings of a turbo is easy as there are two components at work fuel and air. The car’s engine works on a mixture of fuel and air.

The ECU determines the ratio of fuel to air, however, if there is leakage of air along the way, the ratio is incorrectly calculated causing your car’s turbo to work harder than usual. Diesel engines are accommodating in this regard as they are more tolerant of a high fuel to air ratio. However, petrol engines are sensitive, therefore a boost leak inspection is necessary for your car’s optimal performance.

Signs of a Boost Pipe Leak

A boost leak can result in a lot of different symptoms. There are a few of them that are worth looking closer to identify a boost leak. Here are the most common symptoms:

1. Slow Spool

turbo boost leakThe turbo works by increasing the amount of air and fuel that can be fit into a cylinder. Thus, increasing horsepower and performance. However, before the turbo ‘kicks in’ it’s turbine needs to spin very fast, until that happens the turbo does not play a role in boosting the car.

This time, usually called the turbo lag, is when the turbo spools air and fuel to send into the cylinder. If this process is slower than usual, you are experiencing a boost leak. The concept is simple, due to a leak it takes more time for a turbo to spin at maximum capacity.

2. Loss of Power

While you are accelerating, the turbo is giving a boost to the engine motivating it to perform faster and better. If there is a boost leak you will feel a sudden loss of power during acceleration.

3. Check engine light

If you have a boost leak on your car, you will most likely get a flashing check engine light on your dashboard. If your check engine light is flashing, the best way is to read the trouble codes with an OBD Scanner.

4. Poor Idling

This only holds true if you have a car with a mass air flow sensor or MAS/MAF. The MAF senses the amount of air leaving the turbo and entering the engine. If there is a boost leak – which usually happens in the MAF area – your car will have problems idling perfectly. It might stall, close down as a result of the leak.

5. Inconsistent Timing

Your engine tuning will go awry as soon as you have a boost leak. Therefore, any inconsistent sound in your engine is basically due to a boost leak.

6. Excess Smoke Form the Exhaust

The inconsistent working of a turbo will disturb the process inside the engine cylinders. More than the usual amount of fuel will be used and you will see more than usual smoke coming out of your exhaust.

7. Poor Economy

This might not be distinguishable very easily but if you keep an eye on your car’s average fuel consumption you will catch a boost leak easily. If the car is consuming more fuel than it should, you have a problem. A boost leak test can prove to be helpful in such situations.

Boost leak symptomsLow acceleration

Check engine light

Rough Idle

Black smoke from exhaust on acceleration

Poor fuel economy
Faulty Boost pressure pipes

Faulty Intake Plenum

Faulty vacuum hoses
Replace/Repair the boost leak

How to find a boost leak fast at home

Here is a video of how you should do to find a boost leak. However, you need an air compressor to make this possible. You can of course also use an EVAP smoke machine to make this job even efficiently.

DIY Boost Leak test made easy

How to fix A Boost Leak Fast

A boost leak is very easily fixed but first, you need to know what to look at and how to solve the problem.

Check Clamps & Couplers

A boost leak can happen where there are clamps, so it is natural to look for leaks in all the couplers and clamps connecting the turbo to the engine. Maybe a clamp was not properly tightened or it was left loose after you made the previous modification to your turbocharger.

This is a rookie mistake, which is acceptable if you work on your car yourself, otherwise, a mechanic that made this mistake should be replaced. To start with your inspection first take a look at the compressor housing, move towards the vacuum lines next to and work your way to the wastegate controller. Check all the clamps on the way and ensure they are tight an in place and also check for any scratches or cuts the housing.

Use A Boost Leak Tester

Still couldn’t find out anything? No worries, some brilliant minds have invented a device called the boost leak tester. This device does exactly what it is supposed to, it tests leaks for you, so you don’t have to. This is a great tool for anybody who is not experienced in car work and also for those of you who don’t want to spend money taking their car to the nearest mechanical workshop. Therefore, if you can afford one, you can save some precious time.

Using a boost leak tester, you don’t need to start up the car or need to charge up the turbo. In fact, the machine does all the work by itself by pressurizing the system just like a turbo spool. All you need to do is remove the turbo inlet an attach the tester in its place. On the other hand, attach an air compressor to the system and watch the machine build pressure. Now, simply listen for air leakages and mark them.

Boost leak testers are surprisingly cheap and a necessary tool for every turbo car owner. Check out the adapter at Amazon here Torque Solution TS-BLT-BILLET Boost Leak Tester UniversalSymptoms of a Boost Leak & The Causes and make sure it fit your pipes. The only thing you need for this tool is compressed air.

You can also use an EVAP smoke machine to find any boost leaks easy.

Repairing A Boost Leak

Once you have found the leak it is time to patch it up. As we have learned from the information above, leaks are usually found in untightened clamps or couplers. Start off by tightening them up and then checking again until you find all the leakages. If you do need help hire a mechanic but the thing about mechanics is they charge quite a high price for such easy work. Keep in mind a bill of about $100 give or take if it’s the mechanic you are going for.

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7 thoughts on “Symptoms of a Boost Leak & The Causes”

  1. Hi i wonder if you can help. I own fiat bravo 1.9 multi jet diesel 2007 model clocking at 95k. I recently started hearing hissing noise from engine. I had local garage man looked at it mentioned turbo inlet hose split but he don’t have parts available immediately. The problem is I have flight to catch in 2 days and I will be struggling with public transport to reach on time. It’s 60 miles one way and will take 90 minutes roughly. Am I still okay to drive?

    • I guess you have already made the trip. However if it’s a minor leak you can drive it carefully without boost. If the turbo pipe is leaking and you are pushing the turbo fully, you can overrev it and damage the turbocharger/supercharger.

  2. Just had my turbo replaced now when I start the engine not every time I can go at 10mph after about 50 – 100yards it just goes like a steam train any ideas

  3. I have a x type jaguar 2.0 diesel 2004 as soon as I pull away there is a loud whistle that comes and goes in conjunction with pressing accelerator and goes when I take my foot off, car drives perfect with no hesitation or lack of power and no lights on dash evident, tiny bit of black smoke for few seconds on morning startup and then none for rest of day, car is in fantastic condition and only done 100,000 miles
    Help please Gary

  4. Due to a very high demand and high ammount of comments, you have to wait for some time for your car questions to get answered. If you want to get fast answers from a certified master technician you can ask your questions here:
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