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I spent $180 on a used smoke machine last month and it found a leak in 20 minutes that I chased for 3 days with carb spray | Auto Mechanics - Chatter Central

sageadams•26d ago

I spent $180 on a used smoke machine last month and it found a leak in 20 minutes that I chased for 3 days with carb spray

Bought a used smoke machine off marketplace for $180 after seeing the older guy at the shop next door use one. I had this 2006 Chevy 1500 come in with a lean code and a rough idle, and I swear I sprayed half a can of carb cleaner around the intake and got nothing. Hooked up the smoke machine, pumped it in through the brake booster line, and within 20 minutes I could see a tiny wisp coming off the intake gasket at the back of the motor where you can barely get your hand. Job paid 3.5 hours and I had it done in 1.5. I know some of you are gonna say you can build one with a paint can and a soldering iron, and honestly that's fair, but for me the $180 was worth not wasting another afternoon. Now I want to get a better one that does EVAP smoke too, since the cheap unit only pushes low pressure and I've had it not show smaller leaks. What are you guys running for smoke machines and do the cheap ones hold up?

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1 Comment

carr.elliot26d ago

The paint can builds work fine for intake leaks but you already found the wall most guys hit, which is pressure. Your cheap unit probably pushes 1 to 2 psi at best, and EVAP leaks under 0.020 inch need way more than that plus a way to keep the system sealed while you watch the gauge. If you go shopping for one that does both, look at the spec sheet before anything else. A lot of the sub $300 units claim EVAP but only put out around 1 psi, which is fine for a gross leak and useless for the small ones that trip a P0455 or P0456. What you actually want is something with a flow meter or a gauge you can watch, because the smoke itself is only half the job on EVAP. Sometimes you never see smoke at all, the gauge just starts dropping or the flow ball floats up and that tells you there is a leak somewhere in the system. That is the part the cheap machines skip, and it is the whole reason the good ones cost what they do. The other thing to check is whether it has a built in pressure regulator and a low pressure mode, since pushing 2 psi into an EVAP system can blow lines off or hurt the purge valve.