I recently noticed a tapping sound right after startup, while the engine is cold. It's most noticeable when I try to drive it right away still cold. It's a really irregular tapping sound, and doesn't have a consistent rythym.

It sounds like it's coming from the head. If it's valve tapping, does that mean my clearances are too wide, or too narrow?

 

start with adjusting the valves...

https://honda-tech.com/zerothread?id=1305086

 

It could be valves or piston slap. Both of wich are verry common to Honda motors.

 

i agree w/ piston slap, most d16 i have heard do this when cold

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by j4yd3um4lyf3 &raquo;</TD></TR><TR><TD CLASS="quote">start with adjusting the valves...

https://honda-tech.com/zerothread?id=1305086</TD></TR></TABLE>

Actually I recently adjusted them to:
Int=.17mm
Exh=.20mm

The instructions you linked are a bit different than what I did. I measured between where the rocker arm touches the camshaft on my B16.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AutoXer &raquo;</TD></TR><TR><TD CLASS="quote">It could be valves or piston slap. Both of which are very common to Honda motors.

</TD></TR></TABLE>

 

Most of the info I found online related to piston slap is for GM motors.
http://www.pistonslap.com/pistonslap.wav

It doesn't sound like that. (For which I am thankful, because they have pictures of destroyed cylinder walls on the site too)

 

piston slap happens with forged pistons when cold, once they warm up goes away, on my 127kmile d15, i can hear a irregular ticking sound too, after slight warm up is dissapears

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mohsin &raquo;</TD></TR><TR><TD CLASS="quote">piston slap happens with forged pistons when cold, once they warm up goes away, on my 127kmile d15, i can hear a irregular ticking sound too, after slight warm up is dissapears</TD></TR></TABLE>


i was not aware that pistons that are not forged slaped when cold... but i could be wrong

 

afaik due to high silicone content, forged materials tends to expand, once fully warm you wont be able to hear it, as for my d15 i think i need to re-adjust my valves, just to clear things up pistons which are not forged should not piston slap even when cold.

 

I rechecked my clearances and the exhaust valves on number 3 were way too tight. Hopefully that was the issue. I didn't think the SiR II B16 came with forged pistons...

 

piston slap happens on all cars all engines expand under heat, thats why we have clearances for everything (in most cases)