How To Use Smoke To Find a Vacuum Leak

The engine of your car takes in air and mixes it with fuel, which then gets compressed and ignited to generate the power that runs your vehicle. The engine draws in air through a partially closed butterfly-shaped valve, which creates a vacuum in the intake manifold. That vacuum is used to control a variety of different functions that can all be disrupted by air leaks. One of the easiest ways to detect an air leak in your vehicle is by using smoke.

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The Smoke Machine

Professional smoke machines pump a thick white smoke into the intake system and vacuum lines of your vehicle. You can then watch for puffs of smoke in your engine compartment to locate places where the air is leaking out. This process can also be used to find exhaust leaks. Similar equipment is available to use the smoke method to find leaks in other types of equipment, such as a sewer smoke test.

Plug Up the Holes

Before you hook up your smoke machine, you’ll want to plug up any holes in the intake manifold that are supposed to be there. Otherwise, the smoke will just escape, and it won’t help you find any leaks.

Connect the Smoke Machine and Seal the Inlet

Follow the instructions in your equipment’s user manual to connect the smoke machine nozzle to the manifold. You’ll then want to seal up the inlet for the same reason you plugged the holes in the manifold.

Turn on the Smoke

Turn on the smoke machine and let it run for a few minutes. Using a bright light, check your engine compartment for puffs of smoke.

A professional smoke machine is a bit of an investment, but it can save you the hassle and expense of using the trial and error method to find leaking parts. You can repeat this process as many times as you need to until you’ve found all the leaks.