Miata Mailing List: May 1999, Message #74

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Will Brown wrote:

> Been trying to figure it out on my own, but hard to do since it only
> occurs under load, and around 3k rpms.  First thought was the top of
> the CAI loose and vibrating... doesn't seem like it (fits snug, and
> beating on it doesn't produce any hints of the sound I'm hearing)
>
> Have FM shock tower brace and FM hood prop.  Beating on the brace
> makes kinda the same noise... kinda not.  The vibrating hood prop
> also sounds similar, but can't be the culprit, as the prop was just
> put in, and the noise preceeded that part being installed.  Beating
> around up under the dash inside doesn't reveal anything....
>
> Could be in the engine bay, could be in the cockpit.  Not sure what
> I'm hearing, so it's difficult to judge where it's coming from.
> There is sort of a metallic sound to it, but no "edge" - which says
> something metallic in the engine bay, muffled through the firewall.
> Or it's a plastic panel or something, that can vibrate sharply, but
> has no inherent 'metal edge' sound to it, and could be in the cockpit
> area, masqeurading as a metal bit vibrating under the hood.
>
> \/\/

Will

My guess is its the hood.  Mine rattles like crazy.  The black rubber
stoppers are not adjustable and after awhile the hood rattles on its
latch.  Some people wrap the latch loop with tape.  i much prefer to shim
the black rubber stoppers.  Used picture frame corks the first time.
This time I opened the hood and applied some RTV to the top of the
bumpers.  Waited for it to cure and then close the hood.  Got the idea
from Ken Hill.  Works fine.

You can test if this is the noise by putting something like a doubled
over rag on each bumper, close the hood and drive.


--
Larry

White Knight   1991 Crystal White   #99 CSP
Silver Bullet     1992 Silverstone (waiting for StageIV turbo)
Honey B          1992 Sunburst Yellow