does it vary with the speed of the engine? kinda hard just trying to imagine the noise...not sure what the imagine/hear. not too loud, but not too soft...lol

 

Yes, it follows RPM. I plan to have it back together soon, will record once it's running again. But yes, it's not rod-knock loud but loud enough to notice something's wrong.

 

are you low on oil?

 

Have a similar noise and can't figure it out. I think it may be slight leak in the exhaust manifold gasket but am curious to see if you can fix yours.

 

Oil level is proper, I keep a close eye on it and the car hardly burns any.

It seems mystery ticks are a somewhat common issue...

I measured all my LMAs today, each one was 41.6-41.7mm free length. They're extremely simple parts, just a coil spring with a seat on top, so not likely to fail. Since there were no disparities there, I put it all back together paying close attention to each part of the valvetrain (checking for play in rockers, visual on cam bearings, etc). Started the car up and as before: quiet at cold start, after 10 seconds or so the ticking starts building, and then you can really hear it once the air pump shuts off. I tried to record it but when I played the video I realized that my camera's mic is complete crap, I'll try to get a better recording.

In the meantime, I did some more listening and am starting to suspect other things besides the valvetrain. I don't think it's the injectors but it could be some sort of solenoid. The sound either goes away or gets drowned out when the engine is revved over about 2k RPM.

To be continued...

 

this is probably all s2000's.

 

Yeah, although it hasn't ever sounded like this in the 37k miles I've owned the car and appeared during a track day after installing a freshly powdercoated valve cover...

My next plan of action is to do some more "stethoscoping" of various bits in the engine bay to see if I can track this down.

 

Does it seem to come and go? I've noticed some days it does it and some days it doesn't

 

It's always there once the engine is warmed up. I took a video this morning, going to review it tonight and see if it captured the noise well.

 

I recorded the noise yesterday morning before my drive into work and also when leaving work last night. To my surprise, the noise all but disappeared last night. I'm a firm believer in things always getting worse, i.e. mechanical problems don't fix themselves. I'll be keeping an eye on it and if it reappears, I'll investigate further.

I did capture it on video and will upload it.