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have have a 2005 civic 1.7L and I've recently noticed a rattle coming from the engine bay on deceleration. I can hear in two scenarios, while coasting in gear foot off gas (the rattle will go away as soon as I touch the accelerator). The second scenario is in neutral and at a stand still, I will rev the engine and as the RPMs fall it will rattle (pushing the clutch in and out has no effect on the rattle)
At first I thought it possibly a bearing from the transmission but I'm starting to lean towards a cracked header as I've heard that is a common issue with similar symptoms, there seems to be no loose heat shields or exhaust piping but I will take a closer look soon. Has anyone had a similar problem to this?
Car has 340k Km and I recently pulled the transmission to do a clutch kit as well as rear main seal.
Any help is appreciated!

 
Rep Power: 367

removing the header is quite easy, 15-30 minutes, as long as you can remove the frozen bolts...

 
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this sounds too similar to the problem i’ve been having, did you ever figure out what it was?