This is on an s2000. I did a valve adjustment but the noise didn't change one bit. It's constant, and does not stop regardless of how long the motor's been running or even what RPM the engine is at. Interesting thing to note are my compression #s: 220, 220, 210, 260. Yes, the cylinder that's making the tapping noise has unusually high compression.

No CEL. Any ideas? I'm thinking maybe a bent valve or something.

I took this video of it.


http://www.youtube.com/watch?v=rWObWwby4M8

 

Few questions I would like to ask because it sounds to me like it could be a lot worse then what your thinking.

Hows your oil level?
Condition of the oil?
Has the oil light come on recently?
Has the oil pump ever been replaced?
Have you removed your oil pan or valve cover to peek around?
Any recent work performed to the vehicle?

 

Hows your oil level? - Just replaced, perfect
Condition of the oil? - Just replaced, perfect
Has the oil light come on recently? - Nope
Has the oil pump ever been replaced? - Don't think so, just bought the car but the oil pump looks perfect
Have you removed your oil pan or valve cover to peek around? - Yep, no shavings or anything, oil pump looks brand new
Any recent work performed to the vehicle? - Don't think so, I just bought it.

Hope that helps, thanks

 

My concern initially was that you had a spun bearing or a bent rod... I could always be wrong because all I am judging this by is the sound I hear in the video.

I am in no means an expert when it comes to this series motor but I would definitely check your lifters and LMA's as well. I have seen similar but the case I mention the sound went away once the oil started working its way into the head assembly.

I hope a few others can chime in and add their opinions to the topic.

 

Uppity - still needs a fix

 

Pull the plug from the high-compression cylinder, then look and feel inside as best you can. You're checking for deposits inside the cylinder that are crowding the combustion chamber, decreasing space and increasing compression. A small snaking light for finding dropped parts might help you see into the cylinder. Try rigging some sort of stick to poke inside. Touch the piston and see if any black crap sticks to the end. You can work out a tip for the stick that can scoop up stuff sitting on top of the piston. If you find anything, the next step would be cleaning it out, which should really be done with the head off.