I have an older 2001 Honda accord I4 about 160k miles on it. I recently noticed that there’s a rattling sound when the car in in idle (800RPM) but it disappear when I rev it up to higher RPM or while driving. The noise can’t be heard inside the cabin and can only heard outside. The noise also only appears when it is warmed (engine running for about 3 - 5 minutes after cold start). I read from other board about a loose or worn out heat shield so I went under the car and try to look for a loose of broken parts but I cant find any. I removed the cat heat shield but the problem still exist. I don’t know what else to check. Does anyone have idea to share. Car seems run normal, I don’t notice any change in performance and no check engine or what so ever. I just wan’t to make sure it is not something on the engine, transmission, or something that will snowball to a bigger issues. I don’t know how long its been rattling but I just noticed it the other day.
There are 1000 spots that can begin to rattle due to a resonance in older cars. The good news is that yours is doing it at idle and those are relatively easy to find. Pick up a “mechanics stethescope” at the local toolstore (usually about $10) and touch it to various suspect spots. It’ll amplify the sound when you hit the right spot.
Be careful under the hood. Don’t get the stethescope probe caught up in anything spinning, and don’t lean on the exhaust manifold. The former error might put a probe through your ribs, and the latter error might fry your palm off.
Ok. thanks. I’ll try the scope and I have no plans to go underneath while the engine is running or touch it to any moving parts. As long as the rattle is not coming from the engine and/or transmission or any safety components then I’ll let it go… I’ll just play Metallica on the radio to mask it out :). I attach some video (mostly audio anyway) and the rattles start at about t = 1:20. I guess its a MOV file (taken from ipod)
Well, my guess would have been a heat sheild, but it seems that you have eliminated that.
I just heard your audio and it sounds line a clutch release bearing.
The cause of a heat shield rattle is not always something that can be found visually. Sometimes it may take a little prying here and there while enlisting the aid of someone to blip the throttle for you.
try checking the heat shield that sits on top of the exhaust manifold. this is the hottest place in the exhaust system. and is always prone to building rust on them and eventually rusting away the bolt holes that hold it down!!!
Problem found and been corrected… Thanks guys for the feedbacks. It took me a while as I focus on the engine and transmission and cat and luckily not any of those. In case someone else has same symptoms… The root cause is the bolt securing flange connecting the muffler (tail pipe) and the exhaust pipe (after the cat). Bolts are loose enough for the flange to move and hit each other and resonate at idle but tight enough and hard to notice when shaking it by hand or by kicking it. I did a 3/4 turn on each bolt and rattling disappear just like that. Again thanks guys and thank you Car Talk.