Not exactly sure but it sounds like around the intake, number 1 cylinder. Its a 1998 Honda civic EX w 81K miles on it. Its been making the tapping sound for a while. I adjusted the valves as per specs last weekend, and the overall engine is quieter, but I still have this tapping noise in the morning, and even some times during the day when its up to normal op temp. It almost sounds like when you take a PCV valve and rattle it back and forth. It seems to do it on engine acceleration, up to a point, and then back down on deceleration - probably in the 1-2K rpm level.

It does not sound like a knocking noise - I've had massive rod knock on another vehicle, so I am familiar with the sound. This is almost a metallic tapping noise...

Any help appreciated. I wonder if I should seafoam the engine and clean any crap out that might be in the galleys, etc?

Thoughts on what this might be? Thanks again!

 

Possible a noisy lost motion assembly.

 

What exactly is that, and what does it do? More importantly are they easy to replace? Any additional info would be great, thanks!

 

Basically keeps the VTEC rocker arms from smacking around when not engaged.

Very common problem, especially older DOHC VTEC engines. SOHC do have them
(4 vs 8), but I haven't heard too much about them being problematic.

Just a guess really.

 

I believe you have to pull the valve train, which is very easy compared to a DOHC VTEC.

 

Thanks! Can anyone suggest how I can narrow this down? I hate to throw $$$ at something blind... thanks again!

 

Also, I normally run synthetic oil, but it looks like the place that changed my oil this time used regular oil. I was wondering if seafoam to clean the crap (if any exists - I'm faithful on maintenance) would clean things out, or if seafoam is not a good idea? I assume that you run it for a couple of days before changing the oil out? Any input would be appreciated. Thanks again!

 

Bump on running seafoam in the oil? Good or bad thing???? Thanks!

 

Seafoam is good but I dont think it will fix your problem. It is good for cleaning the engine but your only supposed to run it for a few minutes max. It thins the oil and that would create more problems. Im having the same issue. I tried some lucas oil stabilizer because of its thickness but still no change. Im gonna attempt a valve adjusment soon.