Miata Mailing List: March 1995, Message #93
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   From: Dale Kirstein 
Subject: Re: rattling, heat shield?
   Date: Thu, 2 Mar 1995 01:50:27 -0500



On Wed, 1 Mar 1995, Jyri J. Virkki wrote:

> 
> Hello all,
> 
> Well after some 24K miles my Miata quite suddenly developed a very
> loud, metallic rattle.  From the traffic on this list I believe it
> must be the infamous heat shield.  It occurrs at almost exactly
> 3500rpm, nowhere else.  And while it is a very hard sound to place, to
> the best of my guess it seems to come from the general area of the
> down pipe so that fits too.  I haven't looked much into it, just too
> cold out there still!! ;-( Anyway, what's the best way to approach the
> problem, remove the shield or what?  I seem to recall the culprit is
> the shield of the downpipe, not the header shield or the ones furher
> down, correct?
> 
> BTW, it's interesting to note that I find it impossible to replicate
> the rattle in my garage!  When driving, it will never fail to rattle
> @3500rpm.  It's not speed dependent either, since I can always produce
> it by revving up to 3.5K while stopped at a light or whatever.  Once I
> get in the garage however... nothing.  Almost as if it knew that at
> that moment I can try to pinpoint the source, so it decides not to
> make any noise!  Weird. 
> 
> -- 
> Jyri J. Virkki - Linux: Choice of a GNU Generation - DoD#0561
> 
> 

Gee. I could have written that message myself! My 92 just hit 25,000 and
the rattle appeared. I was able to put the car up on ramps, and rev the
car to 3500 rpm, and I found the buzzing heat shield. It was on the
downpipe near the bottom, and one of the welds had cracked off. I guess
this means that I'll have to replace the downpipe since the shield is
welded on ( or was ). At least it's still under warrenty!

Dale Kirstein
92 white Base model.