How to Smoke Test for Vacuum Leaks

Park the car outside in your driveway. Put on the emergency brake.

Remove the cap from the smoke machine. Fill the smoke machine with smoke fluid -- the fluid can be purchased at the same location as the smoke machine. Place the cap back on.

Plug the female end of an extension cord into the smoke machine's power cord. Insert the plug at the other end of the extension cord into an AC outlet on an outside wall -- if there is no outlet, the cord can be plugged into an AC outlet that is inside the house.

Pull the release latch inside the car that unlocks the hood. Raise the hood. Lift up on the hood rod and place it into the hole on the underside of the hood.

Place the smoke machine next to the front of the car. Tape one end of a vacuum cleaner hose to the exhaust hole on the smoke machine with strips of duct tape.

Press the power button to start the smoke machine. Let the smoke start coming out of the open end of the hose before continuing.

Start the car. Start the air conditioning in the car. Hold the open end of the hose against the manifold on the car's engine -- this is the large circular object in the engine. As long as you hold the hose at around the middle of the engine, it will be fine.

Continue holding the hose as the smoke pours out and gets sucked into the engine. Watch for smoke exhaust that is coming out of any hoses on the engine -- this indicates that there is a leak.

Remove the hose and turn off the air conditioning and then the car. Turn the smoke machine off. Pull the rod out of the underside of the hood and close the hood.