Leon serves as one of the leading technical editors for Mitchell1. He is a graduate of Universal Technical Institute and has previously worked for Aamco Transmissions and as a mobile mechanic. He holds 609 Certification and specializes in automotive diagnostics.
In any service shop, a smoke machine is a great investment because of the variety of systems that it can be used to test. The use of smoke machines has proven to be an effective way to locate vacuum, exhaust, gas, oil and coolant leaks. They are also easy to use: simply plug in and turn on. The machines produce a thick white smoke with pressure around 1 psi to 2 psi. The smoke then spreads throughout the system being tested. If there is a leak, smoke will become visible. Using a bright flashlight helps in locating the smoke, especially in dark, cramped areas of the engine bay.
Vacuum, exhaust and gas leaks
Vacuum, exhaust, and gas leaks have proven to be difficult to diagnose due to the leak often being a small hole or crack, thus a smoke machine proves to be very effective.
Smoke machines typically take around one to two minutes to fill the engine and spread throughout, then it’s a matter of spotting were the smoke is leaking from. Small things like a bad gas cap could be the cause of a gas leak, so check the car thoroughly.
1. With the engine off remove the vacuum hose from the PCV valve and pump in the smoke using the PCV vacuum hose. If the
PCV valve isn’t in reach, pumping smoke into the brake booster vacuum hose also works.
2. Check automobile for leaking smoke.
Coolant and oil leaks
Finding a leak with a pressure gauge is one way to test the cooling system, but unless you can see the leak it is not very useful.
Using a smoke machine will allow you to visually see the exact location of the leak. This is also a great way to pinpoint an oil leak without second guessing if you found the source of the leak.
The system should be full after about one minute of pumping smoke, so if there is a leak present it should be visible.
1. To find a coolant leak using a smoke machine you must drain the coolant from the system, then pump smoke into the radiator and look for a leak.
2. Before testing for an oil leak you first must disconnect and pinch the PCV hose so smoke does not leak back into the intake, then seal the crankcase with a piece of tape.
3. Pull the dipstick and pump the smoke into the oil dipstick tube and wait for the smoke to become visible.