Anyone tried smoking engine for vaccuum leaks?

[Socal_dmc]

I was wondering if anyone has ever tried smoking the engine to locate vaccuum leaks? If so, where did you inject it?

[opethmike]

Yes. I have a party type fog machine. I hook it up to any manifold vacuum point. You have to cover the throttle plates with a cap or plastic wrap first.

[Socal_dmc]

What's the throttle plate?

[Delorean Industries]

We use an actually smoke machine for finding EVAP leaks. This is also helpful to find other leaks as well such as fuel vapor leaks along the frame etc.

[David T]

I got an evap machine and tried it on a bunch of cars at the DMA Spring Event. I remove the air filter box, cover the intake with a plastic cover and inject the smoke into the breather hose (the small black hose that goes into the air filter box). Most of the leaks were injector seals but I found leaky "O" rings on the air tube for the idle motor, a missing plug over the mixture screw, a leak in a hose by the charcoal canister, etc. On one car it was coming out of the top of the idle motor! It certainly makes finding vacuum leaks fast and easy! I started by removing a plug on the intake manifold but using the breather hose requires no tools and will not be the source of another leak if you do not seal it up well. When testing you should disturb the car the least possible to not cause additional problems. For a quick fix I just wrapped some teflon tape on the injector seals and the results were immediate and impressive. The motor hunted less and was noticeably smoother at idle.
David Teitelbaum

[opethmike]

After having used my fog machine on several cars, not just my DeLorean, I have to consider a must have tool.

[Delorean Industries]

I agree Mike. Just saw your email btw. Responding shortly.

[David T]

Just FYI a regular fog machine like the DJ's use at parties does not have very much pressure so it may not find small leaks. The older evap testers used 2 lbs of pressure but the EPA deemed that too much so the newer machines only develop 1/2 lb pressure. Even with the older, higher pressure machines you have to wait for a moment or so till the smoke gets into the whole system. What I do is leave the cover off the intake and hold the air sensor down till I see smoke. At that point I release the air sensor and cover the intake. Doing it this way blows the air out faster and gets the smoke all the way inside quicker. My machine also has a cord with a push button on the end to turn on the smoke. Makes it a lot easier to control once you start seeing smoke coming out and helps to pinpoint the exact source. I agree, once you start using it you find all kinds of uses. For instance, it can help find exhaust leaks by pumping the exhaust system full of smoke you can see exactly where the leaks are without burning yourself on the hot manifolds! I also use it when I do plumbing, it finds leaks in the venting system.
David Teitelbaum

[thirdmanj]

Underestimate the power of this forum....

I've been watching this thread with much interest because I know I've got a vacuum leak(s) and I had no efficient way of tracking it down. I never even knew these smokers existed! So I started poking arround online and found a few do it your self kits, but none of it seemed very safe or practical. The good units that I came across were all in the 800-1100 dollar range, certainly not nessary for the part time mechanic. I guess these units are even rare at the professional level too, because I called around a few shops in the area, and the only ones that had a smoke unit was a Chevy dealer who was gonna charge 110 bucks for just a diagnostic!!

Later that day I called Josh at DPI in regards to some weather stripping I'd ordered a couple days back and mentioned my vacuum leaks and the subsequent discoveries about the units and the cost of a diagnostic. Josh offered to lend me his smoker for the price of shipping! Hella cool right?! I mean it sure beats that ridiculous price at the dealership or dropping close to a grang for one, and I can use it for hours if need be! Now THATs support! THANKS JOSH!!!!!

[mluder]

Another option that only costs a couple of bucks...

Using David's process and the breather hose, substitute the $800 smoke machine for a cheap (or expensive if you prefer) cigar. Take a deep puff and blow the smoke into the breather. Cheap but effective.

BTW, not my idea but I had seen it somewhere on youtube.

[stevedmc]

Farrar used this trick a few months back and seemed to enjoy it.


http://www.youtube.com/watch?v=zMok2y05jNE

[David T]

It's a multi-purpose tool. You can develop positive pressure with smoke and you can also develop negative pressure for starting siphons like when you have to suck out gasoline from a fuel tank. Just make sure the cigar is out!!!!!!!!

The smokers are expensive. I got mine used from a Snap-On dealer that took one back in trade for the newer, lower pressure one. I bought it because I had to find a leak in a plumbing vent system that was letting a sewer gas odor into a house. It worked, found a loose clean-out cover.
David Teitelbaum

[Farrar]

Farrar used this trick a few months back and did not enjoy it.

Fixed that for ya.

Farrar