Re: Exhaust Rattle

["Herbert Neily" <neily@domain.elided>]

> From: "Stacy Gary" <spikediesel@domain.elided>
> Subject: Exhaust rattle
>
> I have a mystery rattle around the catalytic convertor at certain rpm's,
like
> around 2500-3500, and especially when I step hard on the gas. I'm assuming
my
> 78 Spider has a catalytic convertor--it could be something else, though,
> because the inside is a straight-tube and doesn't have the honeycomb
section
> that modern cat's have. The suspected unit is about 12" long, is directly
> under the driver's seat, and has a fitting on the side which I assume is
some
> sort of sensor as there is a wire running from it to somewhere towards the
> front of the car. Regardless, the car sounds like a tin can rattling down
the
> street.
> I would love any
> input as to what to do first before I buy a new cat convertor, and also
who
> sells the best cat's out there for performance and price. I just want to
stop
> the annoying rattle.

Before you spring for a new converter, check to see if the "some sort of
sensor" is screwed tightly into its socket in the (possibly) catalytic
converter.  A few months ago, after a short cruise on an interstate highway,
my 84 GTV6 developed a terrible tin can rattle when I slowed to around-town
speeds.  I initially suspected a loose catalytic converter shield or an
exhaust header shield.  I was amazed to find that the culprit was the oxygen
sensor, which had come loose in its socket.  I never would have believed
that a loose sensor could make that kind of tin can rattle, but the rattle
completely vanished after I tightened up the sensor by about a full turn.
Bert Neily
Raleigh, NC

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