My Pro Street

FAQ : How To Locate Boost Leaks

John Huh

It doesn’t get worse than hearing someone tell you that your car is suffering from a boost leak, usually because it means you may have to spend hours locating the culprit of your leak. Often times the coupler can be leaking from a puncture or a cut as it’s exposed to the elements. Cheap clamps, bad intercooler beads and improperly seated intercooler pipes can lead to loss of power, bad gas mileage and in some instances catastrophic engine failure.

We’ll be showing you how to Locate Boost Leaks today to help you improve performance and gas mileage.

How do I know that I have a boost leak?

Sometimes you can hear the leak while the turbocharged car is idling, but usually it’s only under Wide Open Throttle (WOT) and careful monitoring of your boost gauge that you can spot the leak. Finding the leak however is another matter entirely, read further for more information as we test a Mitsubishi Evolution.

Tools you will need :

Today’s vehicle is a 2006 Mitsubishi Evolution, with just bolt on modifications and a severe boost leak that causes the boost to taper to 12psi by redline.

 

To begin we’ll need to access the turbocharger, intake snorkel and of course all the piping that leads from the turbocharger to the intercooler and back to the throttle body assembly. Open your hood and remove the pop rivets that secure the top of your front bumper to the radiator support.

 

A look at the pop rivets that need to be removed on the top of your front bumper bonnet.

With a smaller or shorter phillips screwdriver, slowly start to remove the lower screw rivets that secure the entire underpan to your front bumper. This will take some time as the screw rivets go across the entire front of your bumper assembly. With those pesky screw rivets removed, you can move onto the wheel wells.

 

Once you are done with both sides of the vehicle, now remove the air intake scoop thats located on the driver side of the vehicle by undoing the pop rivets there.

With the air dam scoop removed, you can unplug the Mass Air Flow Sensor (MAF) and the intake tract that leads to the turbocharger inlet.

 

With the MAF unplugged, undo the top of your intake box and undo the 10mm bolts that hold the intake box, intake tract and MAF to your engine bay. Remove the entire assembly and intake snorkel along with your air box, and set them to the side safely.

Undo the last clamp that keeps your intake tract in place over the turbocharger inlet, and disconnect the BOV return by undoing the clamp that secures the recirculating bypass back into the intake tract.

Now plug in your air compressor and let it build up some pressure so that you can test your system. Make sure your air compressor is equipped with a dial to scale back the pressure, do not exceed 40psi at any time when testing your system. Exceeding this level of air pressure may cause damage to your Manifold Absolute Pressure Sensor (MAP), or other related vacuum lines or sensors that are connected to your intake system.

Now take your pressure tester, which is basically nothing more than a coupling with a barb of some sort connected to the other end. You can either purchase a premade unit, or make your own with nothing more than a few handy tools. We show you how to build your own pressure tester here.

This tester is just a piece of metal welded to the back of a 2.5inch pipe, the plate of metal is then drilled and tapped with an 1/8th inch NPT tap, and to finish the unit we used a 90 degree 1/8th inch NPT fitting to a push-on barb. We always recommend a push on barb which ensures a tight fit, use teflon tape or paste to screw your 1/8th inch fitting into place.

Now clamp down the pressure tester to your turbocharger inlet and make sure it’s tightened snugly onto the turbo. Slowly bleed air pressure into your system and release, allowing the air pressure you just fed into the system to work it’s way past the turbo and intercooler. 

Have a friend listen to each juncture to ensure that the coupling and clamps there are not leaking or bleeding pressure, which conversely affects how the vehicle operates. A big part of learning how to Locate Boost Leaks is pinpointing the problem, using spray bottle and the soapy water should react to the leaking clamp / coupler in question.

 

When you find the offending coupler or clamp, we always recommend a light spray of your favorite hairspray to help seal the deal as it were. Use high quality clamps with braces to make sure that there is no warpage of clamps or fittings under boost or heat.

Next up : How To Install Intercooler Kit on a Mitsubishi Evolution

Happy Boosting!

 

 

 

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