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2008 chevy trailblazer_ls
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2 Posts
Discussion Starter #1 (Edited)
I have an 08 TrailBlazer I-6 with 74K miles. It's had a slight clackity-clack noise when cold started, but never a serious issue until today when I cold cranked it and my entire engine compartment sounds like a busted muffler. More odd, I have zero faults, and the holey-exhaust noise disappears after about 5 minutes of driving. All indicators point to a cracked exhaust manifold, yet the sound doesn't stay. Also, even after it's been running, if I shut it off and restart it, the sound returns until about 5 min of driving. Aside from the clackity-clack, it runs smooth. I'm not experiencing any acceleration issues, but a slight fuel smell when the noise is present. Any takers?
 

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2003 gmc envoy_slt
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7,190 Posts
If there is a crack, as the manifold heats-up, the metal expands and seals the crack. :m2:
 

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2008 chevy trailblazer_ls
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Discussion Starter #3 (Edited)
Basic Science didn't allude me ...

.... however, I seem to have been taken aback by the suddenness of this issue. I was assuming the metal-expand-go-away logic until turning it off after a one-hour commute and immediately cranked it up to hear the same thing. *flustered* Either way, I doubt this is cheap ...
 
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