Whistling Classic

[Eric Seppanen]

On Mon, Jan 28, 2002 at 12:51:36PM -0600, Brad Richards wrote:
> I put a HotShot header on my '93 a few months back, and have had an
> annoying vacuum leak ever since.  At least I'm assuming it's a vacuum
> leak -- it acts and sounds like one.  It only happens under pretty
> significant load, so I can't just stick my head under the hood and
> see where it's coming from.
<snip>
> Is there some likely place to look, given that I only hear the
> whistle under significant load?  Anybody else have this problem after
> a header install?  The pitch of the whistle is almost speed
> independent -- it rises in pitch slightly, but it's much more
> dependent on load than engine speed, so I doubt it's a belt or pully
> or some such.

This sounds suspiciously like a problem I had, which turned out to be a
partially-blocked catalytic converter.  If you don't have significant
power loss, yours might not be as blocked as mine was, but a
whistling/rushing-air noise under load sounds like there's something
obstructing the exhaust.  Perhaps you dropped something in there?  In my
case the cat itself was breaking apart inside and the loose bits were
obstructing the airflow.

I thought exactly the same thing: sounds like a vacuum leak.  But a
professional mechanic friend pointed out that vacuum goes _down_ under
full-throttle, so that doesn't sound like it.