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
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!