at idle the car has a small tapping sound to it. the tapping is only happening at random times and is not a constant tap. lets say, at idle, if the sound was constant if would make a tap every 0.5 secs but it actually taps at random times. sometimes it will make the noise in a fast pace and then stop for 2-3 secs and start again.

It started yesterday driving home from work. I was going over the bridge and decided to take 3rd gear as far as it will go. well when the car gets to about 3700rpms it makes a horrible loud clanking noise. I thought my car developed VTAK! This is the only thing that does happen consistently. the only time that the noise does not happen is when the car is in park or neutral.

this is the part that makes me think its not my engine. when in park or neutral i can redline and hear nothing wrong. when it idles down i hear the small inconsistent tapping. but if i just rev it up a little the tapping disappears. the small tapping noise does not raise with the engine.

last thing.. there is no performance failure. car is running strong still. no black smoke when reving. so park, neutral idles with small tap but goes away when rev'ed and does not make any odd noises no matter how far its rev'ed. in drive still small random tapping at idle but when rev'ed it goes away and at 3700rpms i hear a horrible clanking noise but performance and stability seems to still be there. no hesitation in throttle response or breaking up when it passes 3700rpms. just a lot more noise.

I've been told it could be push rod, spun bearing, and the one im hoping for is cracked flywheel. this is an auto if that makes a diff. its a 93 formula firebird. The tapping noise did get a little more noticable after driving and listening to it idle but is still not a steady tapping at all. Please give advice. Let me know what you think.