Can anyone identify this sound?

I've got a 99 Altima with an odd sound to it while accelerating. It's a regular thrumming, sort of "fluttery" sound. My 94 has a very similar sound as well, but a bit more harsh I think (due to less sound deadening maybe), so it could very well be normal. I'd really like to know what causes it though.

I went for a drive and recorded the sound inside the cabin, it's a bit hard to make out but any time I accelerate it's there. It's most noticeable under moderate acceleration it seems.

I've got a short clip and the full length at

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To me it almost sounds like a resonance that is happening somewhere, in the exhaust manifold maybe or some part of the engine bay. I had a Civic a few years ago that due to an accident and repair had the engine mount touching the frame of the car and unless I wedged something between the two parts, I would get nasty sounding knocking/vibration while driving. Maybe this is the same sort of thing. It's almost like some metal part of the engine is vibrating against the hood, or the frame, or something.

Also, I get a slight tapping for 1 or 2 seconds at startup when the engine is warm (but has been sitting for maybe 20 minutes). You can make it out faintly at the start of the longer recording here. I've been told it may be a stuck lifter, so is there any chance that that could account for the noise? I would expect something like that to have a lighter sound to it than this does, but I'm no expert. I've been telling myself that it's happening (revolving) too quickly to be something to do with a particular cylinder or valve, but again, I'm just guessing.

I know it's pretty hard to make any guesses, educated or otherwise just based on a couple of hard to make out samples, but I would like to hear any theories just the same.

Thanks!

Reply to
JM
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Please post the dance version.

Reply to
doS

I know, I was just trying to keep up ;)

Reply to
JM

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