Automotive smoke machine questions

[67drake]

I’m thinking about buying a smoke machine for diagnosing vacuum leaks and such on vehicles. Never having owned one I have a few questions from those of you that have used them.
For example, if checking for a vacuum leak on my old carbureted cars, I assume I’d have to block exhaust, breathers, and carburetor somehow to build pressure correct? How do you reasonably do this? Especially the carb. Is there enough air flow out of these machines that you can just “kinda” block these off, or do they have to be completely sealed off for smoke to roll out of the leaking spots?
Do these machines work for oil leaks also?
Actually ANY real world experience using these would be appreciated!
Thanks!

 

[Wrench97]

Can't say I've ever tried it on a carburetor, but generally on newer FI you just use the blow up bladder in the air intake hose/throttle body turn the machine on and look for the smoke never had a issue with the exhaust/intake valves being open causing a problem.
I suppose you could adapt a hose to go over the top of the carb and put the bladder in the hose.

 

[cgrutt]

I actually made a DIY smoker to track down a problem with a previous F150 it worked surprisingly good and was a fraction of the price for a "real" smoke machine. Not sure if that would work for your situation I'm not a pro just working on my own vehicles. I seem to recall watching some videos where they just zip tied nitrile gloves over the exhaust, throttle body etc it seemed to work well.

 

[2ndGearRubber]

I’m thinking about buying a smoke machine for diagnosing vacuum leaks and such on vehicles. Never having owned one I have a few questions from those of you that have used them.
For example, if checking for a vacuum leak on my old carbureted cars, I assume I’d have to block exhaust, breathers, and carburetor somehow to build pressure correct? How do you reasonably do this? Especially the carb. Is there enough air flow out of these machines that you can just “kinda” block these off, or do they have to be completely sealed off for smoke to roll out of the leaking spots?
Do these machines work for oil leaks also?
Actually ANY real world experience using these would be appreciated!
Thanks!

For a smoke machine which can also do EVAP work, a flow gauge will be added to measure rate of flow/decay of a sealed system.

For looking for vacuum leaks, non-designed/accounted for vacuum leaks, you will not be using the flow gauge. Peak pressure is typically about 1psi. On a carb, you can block the inlet piping with a bladder attachment, or plumb in downstream and block the carb inlet itself with a glove or similar. No need to block the cylinders or otherwise, 1psi of smoke will find vacuum leaks very quickly.

Very small leaks will be present around shafts, like EGR valve, throttle bushings, etc. This is normal and accounted for airflow in the mixture jet size or PCM programming.

If the engine is 100% cold, they can be used for oil leak detection. If the engine is warm, the smoke will typically absorb/disperse in the hot engine. I've seen it done for diagnosing leaking front/rear main seals on engines with a sealed crank-case. Some older stuff has a sealed crankcase, just like a modern vehicle, FWIW.


If not doing EVAP system work, you do not need a unit with a flow gauge. However without a flow gauge, the system is generally useless for EVAP work.

 

[charbar]

What they said^^


And I would just splurge for one with a gauge now and be done. If you have a smoke machine you will inevitably be using it for EVAP leaks...

 

[mikegt4]

I bought one to track down an EVAP leak, worked great. IIRC it is a "Stinger" brand machine, puts out smoke like a steam engine.

 

[signcrafter]

I have a chinese one off amazon or ebay. It was something like 150 bucks I think. It has more then paid for itself. Works good and has found a bunch of leaks more then paid for itself.

 

[67drake]

Thanks everyone.

 

[rust in the eye]

I have a chinese one off amazon or ebay. It was something like 150 bucks I think. It has more then paid for itself. Works good and has found a bunch of leaks more then paid for itself.

Perhaps this one;https://www.ebay.com/itm/1956780741...uAmJmnWx_BPx-TP4HxtblZNKA_JfAeATXdPcm4kBQVdEX
I have it, works for me.

 

[signcrafter]

Perhaps this one;https://www.ebay.com/itm/1956780741...uAmJmnWx_BPx-TP4HxtblZNKA_JfAeATXdPcm4kBQVdEX
I have it, works for me.

Looks similar and think that's the brand. Mines yellow. But mine has a flow meter.

 

[trackwelder]

I purchased this one recently. Worked very well

VEVOR Automotive Smoke Leak Detector Smoke Machine Tester EVAP Fuel Pipe System | VEVOR US

Discover VEVOR Automotive Smoke Leak Detector Smoke Machine Tester EVAP Fuel Pipe System, Full System Diagnostics and Easy to Operate at lowest price, 2days delivery, 30days returns.

m.vevor.com

 

[redmondjp]

I just use the 2" wide painter's masking tape to seal up the carburetor air horn opening. It may take some tweaking to get it perfectly sealed, but it works.

 

[tak1313]

When I was researching smoke machines, one of the issues I came across (for EVAP testing) was that a LOT of the cheaper ones on Amazon et. al produced too much pressure.

I forget what the limit was, but the spec was SIGNIFICANTLY lower than just about all the no-name/cheap ones on Amazon and Ebay.

I'm not a pro, so can't comment on the ramifications, but apparently in some EVAP systems, going above the limit can damage sensors in the system because they were not designed to come across pressures above Xpsi.

Edit: Did a quick search to refresh my memory, and a lot of info out there saying it should be less than 1 psi to avoid damage (more in the range of 0.5 psi), but a LOT of the Amazon/Ebay machines run about 7 - 10 psi, which is fine for intake, exhaust, etc. testing, but not for EVAP.

 

[mikegt4]

Today I looked at my smoke machine mentioned in my post above, it's a Stinger Pro 2. I bought it a few years ago when it was on sale, maybe Black Friday or similar event. Like everything it's a bit pricier today.

Stinger Smoke Products - Smoke Machine Products for EVAP and Automotive Smoke Testing - EvaporativeSmokeMachines.Com

Stinger Smoke Products Sells Smoke Machines and Smoke Products for Testing EVAP Systems, Intake Manifold Leaks and Automotive Smoke Tests

evaporativesmokemachines.com