So all those fancy smoke machines are a bit out of budget, but I've got a really loud vacuum leak and I'm not too keen on accidentally setting my engine on fire with carb cleaner sprayed all over the millions of vacuum hoses on the 1987 Turbo-II. That, and idle is currently so unstable I wouldn't even be able to tell if the carb cleaner had any effect. I've seen a lot of DIY smoke machines that basically involve somehow frying mineral oil (which is how I believe the professional machines do it anyhow) and pumping the smoke into a vacuum line with the engine off. Most use some sort of combusting element, i.e. burnt out barbeque briquets or assorted wood tinder to burn the mineral oil. Someone mentioned something about embers getting into the evaporative system and said not to use anything that burned. If I were to do something like this, would the embers justify finding a flameless electric heating element to rig up a smoke machine or should I be fine with the briquets? If so, what would be ideal to use? Another person mentioned those smoke-in-a-can things used to test fire alarms. Would this work as well?

 

If your leak is as pronounced as you say it is just do a standard boost leak test. Remove intake/air filter, fit a PVC cap with Schrader valve into the intake/TID, use an air compressor to pressurize the system with a little air and listen for the leak. Once you've narrowed down the approximate location spray soapy water and look for bubbles.