Smoke testing?

[ragamuffin]

Hey here is a new one on me. I've never heard of this on any car I ever owned or anyone else's for that matter. My check engine light would not stay off for anything, even after the new radiator was installed. Running great, so I took it in for a check and they said it was leaking fuel vapors from somewhere, and so they fill the gas tank with smoke to find the leak. Then they replaced the fuel line at the leak and all is well. For 300$.

Ever heard of that?

Just curious, ragamuffin.

[85merk]

yes a smoke machine is used to find EVAP leaks.
the smoke is harmless, it does not affect the fuel at all.
i had it done as well.

[Bill Putney]

Smoke tests are common in automotive and in industry in general as well. I used to be in charge of production batch ovens that had hydrogen gas piped in for a controlled internal atmosphere. As you might imagine, it is critical that they not leak. Certain industrial catalogs list smoke bombs because they are commonly used for leak testing all sorts of vessels. Not uncommon to use cigarettes to generate smoke for such tests (though it's thankfully harder to find people around who can contribute in that service now) (and - no you would not test for hydrogen leaks using hydrogen with anything lit lest you want to be a candidate for a Darwin Award - purge the hydrogen, then test using air - duh! Never test for leaks in a gasoline system with anything lit due to vapors - who doesn't know that, but thought I'd better mention that anyway).

[tinman]

Smoke tests are common in automotive and in industry in general as well. I used to be in charge of production batch ovens that had hydrogen gas piped in for a controlled internal atmosphere. As you might imagine, it is critical that they not leak. Certain industrial catalogs list smoke bombs because they are commonly used for leak testing all sorts of vessels. Not uncommon to use cigarettes to generate smoke for such tests (though it's thankfully harder to find people around who can contribute in that service now) (and - no you would not test for hydrogen leaks using hydrogen with anything lit lest you want to be a candidate for a Darwin Award - purge the hydrogen, then test using air - duh! Never test for leaks in a gasoline system with anything lit due to vapors - who doesn't know that, but thought I'd better mention that anyway).

To add to Bill's comments, some shops will weld up gasoline tanks that have leaks (NOT OURS!). They get as much gas out as they can and pipe car exhaust into the tank. Good luck with that one, too, Darwin. As a matter of fact, I "knew" someone who truly was a really, really stupid individual who torched open a partially filled 55 gallon drum of gasoline.

[FIREM]

I'll bet torching the drum "let the smoke out" !!!
The fuel system on modern cars is sealed and partially pressurized. The low pressure is monitered by emissions systems and prevents gas vapors from being releasesd. Smoke lets the tech locate the source of the leak and take corrective action.
Ever notice at a car show the "real cars" have that special aroma (the tree huggers hate it)
Come to Carlisle and experiance the scent !!

[ragamuffin]

Ok. Now I get it. It reminds me of the "peppermint bombs" my Dad used to use in plumbing many years ago to find leaks in tall buildings or underground pipes.

I'm a learnin'.

Thanks for the replies.
ragamuffin

[Bill Putney]

Ok. Now I get it. It reminds me of the "peppermint bombs" my Dad used to use in plumbing many years ago to find leaks in tall buildings or underground pipes.

I'm a learnin'.

Thanks for the replies.
ragamuffin

You're welcome. Ahh - the smell of peppermint and crap! mmmm