Checking exhaust system for leaks

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gdizzle

gdizzle

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I am interested in checking exhaust system for leaks. dddart 66 with 6cyl. exhaust system looks old and original. muffler is a Imco 28. I searched on www and there are guys that are hooking up a vacuum to the exhaust and running it (blowing it back into pipe) and then checking with bubbles sprayed onto pipes etc... My question, is this ok to do? Is there any sort of damage that can occur to the engine by blowing into it from the exhaust?
I also saw a guy letting vacuum cleaner suck out of the exhaust and then go listen to the pipes and hear a hiss?
 
You can just feel around it while it's running and find leaks.

The vac won't hurt it if you go that route, but I can't imagine being able to hear a leak with the vacuum running:D
(the bubbles part), yea that would work if you want to spend a bunch of time spraying soapy water on your exhaust.

And then there's the smoke machine route. (a whole nother pain in the butt if you don't have one)
 
what is wrong with running the engine with a glove or towels over the tailpipe?
 
yea I did see someone on the internet that stuck a rag in the pipe. Also rather not feel around on the pipes and get burned.
I do have a smoke machine, how would I make that work? And wouldnt the smoke machine residue gum up the valves?
 
with the car running block the tail pipe (I usually use my hand real quick) if you get back pressure and can't keep it blocked - no leaks. If it is leaking, your hand will stay there with no trouble (don't linger, it gets hot pretty quick) - finding most leaks can be done by ear - get the car up on stands and roll yourself under there - verify what you hear with your hand, you'll be able to feel the "air" coming from the pipes etc. - also, if the car isn't running clean you'll find carbon stains where the leaks are
 
And.........when you get some leak semi found, like in the mess of header tubes, etc, take a scrap piece of hose.........3/8 works as well as anything, and hold one end up to your ear.
 
gdizzle said:
yea I did see someone on the internet that stuck a rag in the pipe. Also rather not feel around on the pipes and get burned.
I do have a smoke machine, how would I make that work? And wouldnt the smoke machine residue gum up the valves?
Click to expand...

I don't think it should be any issue at all, especially if you fired it up right after.
If smoke machines caused problems people wouldn't use them.

The rag in the pipe would cause a lot of backpressure as well as muffling the engine so you could hear.
Small leaks will produce a loud hiss as the back pressure builds, but big leaks you still have to locate via sound and feel.

(And I never said "feel the pipes"), but feel close to them for pulses of exhaust because you can feel it a lot better than you can hear or see it.
It's not a big deal if you don't go sticking your hands all over header tubes and stuff. LOL

Del mentioned a tube to pinpoint sounds, and that works really well for tight places like around header flanges. and collector gaskets.

I could find any leak in my entire exhaust system in under 2 minutes I guarantee you, but you also might hear a "OUCH ****" once or twice. :D

It's worth it.
 
The most un-scientific way is to stuff a potato up the pipe. Don't laugh, it works. Just cut it out with a knife.
 
toolmanmike said:
The most un-scientific way is to stuff a potato up the pipe. Don't laugh, it works. Just cut it out with a knife.
Click to expand...

This is the way to blow a big hole in a weak muffler,, ask me how I know..

As mentioned , a friend holding a cloth over the exhaust, preferably with a glove,, cuz it'll get hot,, and just hold as much pressure as poss,, then you move along the pipe,, any leaks will be quite evident..

This is Standard muffler shop technique

hope it helps
 
You haven't seen the "Red Neck" home made smoke machine?? I think it was here on FABO somewhere (video clip). You get a 2 liter soda bottle poke a hole in the cap large enough to fit a cigarette. You poke another hole in the bottom of the bottle to fit an air hose hand held blow gun then light a cigarette , stick it in the cap (with the burning end inside the bottle) then blow air (slowly into the bottom hole). The air will burn the cigarette down causing smoke to come out the end of the cap (where the cig filter sticks out). Then you just duck tape it to your tail pipe and have someone look for the smoke coming from a leak while you blow smoke into the tail pipe!!

treblig
 
there's a blonde joke in here somewhere.... :twisted:
Treblig said:
You haven't seen the "Red Neck" home made smoke machine?? I think it was here on FABO somewhere (video clip). You get a 2 liter soda bottle poke a hole in the cap large enough to fit a cigarette. You poke another hole in the bottom of the bottle to fit an air hose hand held blow gun then light a cigarette , stick it in the cap (with the burning end inside the bottle) then blow air (slowly into the bottom hole). The air will burn the cigarette down causing smoke to come out the end of the cap (where the cig filter sticks out). Then you just duck tape it to your tail pipe and have someone look for the smoke coming from a leak while you blow smoke into the tail pipe!!

treblig
Click to expand...
 
ScampMike said:
there's a blonde joke in here somewhere.... :twisted:
Click to expand...

Ha HA!! Or LOL for you young'ns

[ame="https://www.youtube.com/watch?v=HRiK2HEA3QQ"]Checking for vacuum leaks using home made smoke pump. - YouTube[/ame]

Here's a video that uses the same idea except this guy used a can and a cigar.

treblig
 
if i run a smoke machine into the exhaust pipe, do I have to remove carb and plug up the intake? Or what is stopping the smoke from traveling all the way up through the carb?

let me know I am ready to start making smoke
 
If you suspect the leaks are in the piping just remove the collector connection and plug the pipe at the front. That's probably the easiest way. If you find no leaks in the pipes/mufflers then you know it in the headers/manifolds. You could plug off the carb (rags) and check everything. Be prepared to use two or three cigarettes/cigars to fill the whole system.

treblig
 
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