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Old 06-13-2018, 06:32 PM   #1
jabborabbo
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Best way to find an exhaust manifold leak?

So I rebuild the carb and the old ‘67 runs like new...then the nasty click noise starts...it’s kinda loud when I first crank the truck, then it goes away when the engine warms up except it comes back when I accelerate, so I assume it’s a manifold leak, and I’m dreading what the fix may entail since the manifold has never been removed...so what’s the best way (or various good ways) to locate it?
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Old 06-13-2018, 07:38 PM   #2
GASoline71
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Re: Best way to find an exhaust manifold leak?

Take 2' piece of old garden hose and hold one end to your ear and use it like a "stethoscope" moving all around the manifold with the engine at idle. You'll know when you hear the leak.

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My 1972 GMC 1500 Super Custom (Creeping Death) "long term" build thread.

The Rebuild of Creeping Death after the wreck

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I would never rebuild a 305.
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I love using vacuum gauges as part of the carb tuning process. I hook the gauge to the inside of my garbage can and leave it there.
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Remember Murphys 2nd law of mechanical relationships... "OPPOSING COMPONENTS ATTEMPTING TO OCCUPY THE SAME SPACE, AT THE SAME TIME, GENERALLY END UP OCCUPYING ADJOINING SPACE AT THE BOTTOM OF THE OIL PAN"
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Old 06-13-2018, 09:07 PM   #3
randy500
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Re: Best way to find an exhaust manifold leak?

Have someone put their hand over the end of the exhaust pipe(s) while you look for the leak under the hood.
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Old 06-13-2018, 09:32 PM   #4
CastIron
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Re: Best way to find an exhaust manifold leak?

I haven't actually tried this... but I wonder if you could just put a vacuum hose into a container of ATF and watch for smoke. I wouldn't recommend too much ATF at once, but a little won't hurt the engine.
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Old 06-14-2018, 09:40 PM   #5
BCOWANWHEELS
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Re: Best way to find an exhaust manifold leak?

your bare hand on cold engine running
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