Using Smoke to detect vacuum leaks?
 

Has anyone ever used smoke to detect small vacuum leaks? If yes, what is used to generate the constant smoke?

i was going to just smoke a lot of cigs, but I wonder if one could hook up a little fog machine like this one http://www.amazon.com/dp/B00F2ATK18?psc=1

A smoke machine! I know someone who has one and he gave me a demo. Very cool device. Love to have one but is more than I'd want to spend (around $800 to $1000). It uses mineral oil which is heated by a glow plug to generate the smoke in simplistic terms (I'm sure there's more to that). Would love to build one at some point.

https://www.youtube.com/watch?v=m1OUIfIs8A0

https://www.youtube.com/watch?v=PaYd4-uVlQE

there are (probably cheaply made) fog machines on Amazon for like 50 bucks.

Bee keepers smoker

I once rigged a smoke apparatus to find a leak in a mazda 2.3 engine (hidden PCV leak)

I had an empty paint can with lid, I put two holes in the lid and shoved some hose on it and applied RTV too. you use one hose as your connection to the engine and one connected to an air source e.g. funnel and fan, your mouth, shop vac on blower mode. (imagination wins)

inside the can I placed a small bowl made of alu foil and filled it with cooking oil - I then dropped a hot piece of charcoal on it and closed the lid quickly. It worked really nice.

The only downside is that your work smells like a barbecue afterwards.

I did find on Amazon a product called Smoke in a Can which is used to test smoke detectors.

We use a smoke machine in my shop everyday. Engine vacuum leaks, EVAP leaks, pneumatic locking systems on the older cars..............

Do use smoke internally under pressure to see where it comes out, or do you use it externally to see where it gets sucked in?

I built one with a empty paint can, a 1/4 npt nipple which connected to an air regulator and a 1/4 barb fitting.

Brazed the fittings into the lid, could have rtved or jb welded instead. start a fire inside the can, with leaves or something, then put the lid on and turn the air up until you get a slow stream of smoke, not too much, then connect a hose from the can to wherever your vacuum lines go.

has worked wonders for me in the past. going to develop a better version soon.

Internally under pressure.......

OK. Just wondered. I have tried using it externally to find intake manifold leaks, but didn't work too well.

I'm looking for a vacuum leak in an '85 300D. Right now I'm at the symptom level: If I drive the car and don't lock the doors, the transmission shifts with a lurch, and then the engine won't shut off. Lock the doors (using the driver's door central lock) and the rough shifting and no-shutdown goes away. My guess is that it's a leak in the door locking mechanism?
The secondary problem may not be related at all; the AC compressor won't kick in, and the heat is on full-bake, no matter where the climate controls are set. My guess about this is that it's the control module, maybe broken solder joints?
I'd appreciate any comments or advice.
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Recently I went through this problem on my 1983 300TD wagon. First you need to have a Mityvac vacuum pump (the pump has a vacuum gauge). The yellow/grey stripe vacuum line is the one that provides vacuum directly to your vacuum reservoir. Locate the vacuum reservoir (in the trunk located under the parcel shelf), pull off the vacuum line from the reservoir and plug the line with a golf tee. Locate the same yellow/grey stripe line under the hood and using your Mityvac apply 20" of vacuum to this line. This line should hold the vacuum for at least 1 hour (hopefully longer). Next check the reservoir itself by applying vacuum to the reservoir (it will take several pumps of the Mityvac to achieve 20") and see if the vacuum holds for at least 1 hour.

Next, using your Mityvac, disconnect the vacuum lines from the vacuum line that goes from the vacuum pump to the brake booster. Hook your Mityvac to the vacuum T that is close to the brake booster and cap off the other T. Start the engine, you should see a minimum of 20" of vacuum. If anything below 10", you need a ew vacuum pump, or new pump check valve.

Do these checks first, post your results, and if needed we can provide further checks.

In grad school I made one out of a peanut butter jar with two rubber hoses. I put a 12v Harbor Freight air compressor into the end of one, and theend of the other one attached to the manifold with duct tape. Inside the jar, I shoved a cigarette into the hose with the end in the manifold. Lighting the cigarette, closing the jar and turning on the compressor was enough to fill the entire engine with smoke. It cost like $4 for the smokes, and the rest I scrounged. Easy and cheap.