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Old 11-14-2014, 09:31 AM   #1
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Default Leak testing exhausts off a car

What is the proper way to leak test exhausts when you have them off a car? The setups I am building use v-bands, so should I just machine a circle of metal that I can stick in the v-band clamp and put some sort of valve on it to hook my air compressor? Then listen for leaks?
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Old 11-14-2014, 09:34 AM   #2
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Put one end in a big bucket and fill the exhaust with water?
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Old 11-14-2014, 09:52 AM   #3
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That seems like a really bad idea. Wouldn't filling an exhaust with water possibly cause it to rust faster on the inside? Would it not damage the inside of the muffler if it was full of water?
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Old 11-14-2014, 09:56 AM   #4
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fill it with smoke.
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Old 11-14-2014, 10:03 AM   #5
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smoke machine

or a cigar + hairdryer/fan if you wanna do it cheap
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Old 11-14-2014, 10:16 AM   #6
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Smoke machine will be purchased. Party at my garage, who has a disco ball we can hook up?
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Old 11-14-2014, 10:19 AM   #7
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or hook it up to your smoker and have all your exhausts smell like smoked pork, which will increase value by 400%

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Old 11-14-2014, 11:01 AM   #8
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d00d. yes.
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Old 11-14-2014, 11:37 AM   #9
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Quote:
Originally Posted by shuiend View Post
That seems like a really bad idea. Wouldn't filling an exhaust with water possibly cause it to rust faster on the inside? Would it not damage the inside of the muffler if it was full of water?
You've not made a stainless exhaust?

There is always water in exhausts anyway, ever noticed how much condensation is created on a cold start?

I really don't think it's a big deal.
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Old 11-14-2014, 12:01 PM   #10
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pressurize it and spray vbands with soapy water. Or smoke machine, we have one at the shop it makes finding pinholes very easy but they arent cheap. I'd say your best bet is a pvc pipe cap a silicone coupler and a pressure regulator. set it to 10 psi and spray all connections with soapy water, watch for bubbles.


Edit: This method also works well for leak testing charge pipes. set the regulator to 30psi and it makes rooting them out easy. Sometimes we encounter boost leaks that only leak under pressure, and our smoke machine doesn't do anything above 10psi.
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Old 11-14-2014, 12:19 PM   #11
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Quote:
Originally Posted by richyvrlimited View Post
You've not made a stainless exhaust?

There is always water in exhausts anyway, ever noticed how much condensation is created on a cold start?

I really don't think it's a big deal.
Exhausts are made out of aluminized steel to keep costs down.

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pressurize it and spray vbands with soapy water. Or smoke machine, we have one at the shop it makes finding pinholes very easy but they arent cheap. I'd say your best bet is a pvc pipe cap a silicone coupler and a pressure regulator. set it to 10 psi and spray all connections with soapy water, watch for bubbles.


Edit: This method also works well for leak testing charge pipes. set the regulator to 30psi and it makes rooting them out easy. Sometimes we encounter boost leaks that only leak under pressure, and our smoke machine doesn't do anything above 10psi.
I am probably going to go this route. Will head up to the metal shop sometime next week to get them to make me some caps that work with he v-bands. Then pick up a cheap fog machine to pump in the smoke.
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Old 11-14-2014, 12:27 PM   #12
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Quote:
Originally Posted by shuiend View Post
Exhausts are made out of aluminized steel to keep costs down.



I am probably going to go this route. Will head up to the metal shop sometime next week to get them to make me some caps that work with he v-bands. Then pick up a cheap fog machine to pump in the smoke.
Why not just drill 2 holes in one of the caps, install a Schrader valve in one and a pressure gauge in the other. Pressurize and watch the pressure drop or not. Apply soapy water if it drops to find the leak.
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Old 11-14-2014, 12:33 PM   #13
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Why not just drill 2 holes in one of the caps, install a Schrader valve in one and a pressure gauge in the other. Pressurize and watch the pressure drop or not. Apply soapy water if it drops to find the leak.
That is another idea that would work. I will see what I get made next week and go from there.
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Old 11-14-2014, 01:56 PM   #14
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For the vband end you can take a spare v-band flange and weld a flat plate over it and weld a pipe fitting onto it with a shrader valve, on the tailpipe end buy one of the pimp silicone pipe caps they use for back purging. Put 5-10 psi in the thing and spray with soapy water.

Or you could just give it a good visual check and call it good. If a leak passes visual its going to be pretty tiny that the only way you're probably gonna find it is seeing a tiny carbon streak on the exhaust that starts at the pinhole.
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Old 11-14-2014, 02:26 PM   #15
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Quote:
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Exhausts are made out of aluminized steel to keep costs down.
Fair enough. They're still filled full of water every cold start tho.
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Old 11-14-2014, 02:27 PM   #16
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Quote:
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Fair enough. They're still filled full of water every cold start tho.
Not enough to completely saturate the muffler packing though.
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Old 11-14-2014, 02:28 PM   #17
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Quote:
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Not enough to completely saturate the muffler packing though.
Once it's drained out it's the same thing.

Also re the pinhole leaks not mattering. I can hear a pinhole leak.
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Old 11-14-2014, 02:36 PM   #18
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Quote:
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Once it's drained out it's the same thing.

Also re the pinhole leaks not mattering. I can hear a pinhole leak.
Yes you can hear a pinhole leak, you can also see it in a visual. The leaks you wont find are the ones that only seep the carbon out with the water in the exhaust and the path is so convoluted it takes a long time for it to travel, no significant exhaust gasses pass through them. I made an illustration, pinhole on the left, leak you wont catch with a visual on the right.

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Old 11-14-2014, 03:31 PM   #19
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You guys are making this whole thing overly complicated. I asked because my welds are by no means perfect, some times they look like they were done by a blind 5th grader, I just want to make sure they are all good enough to keep exhaust gas in.
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Old 11-14-2014, 04:14 PM   #20
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Fill with gasoline and go along the seams with a cigarette lighter. Problem solved.
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