Cat hole - should this be plugged ???

[TEX TERRY, II]

From: "Ice Cat     ^. .^   ~" <iceisit at earthlink.net>
(snip)
My husband went to pull the cat while I was out and he found this
hole in the cat on the passenger side about 1/3 of the way up from
the bottom . . .  if you were on the passenger side of the car
looking at it from the side horizontally, the hole would look to be
1/3 of the way up from the ground.
Instead of pulling that cat like I asked him, he just plugged the hole.
Anyone know whether this hole *belongs* there ?
Is it going to blow up if it is plugged ?
Thanks    Fay
(snip)

As a matter of safety, to avoid carbon monoxide fumes from getting inside
the car, any holes whatsoever, that are found in the exhaust system, should
be plugged, then at first possible chance the section, of the exhaust
system, with the hole should be replaced.  A hole will ususally be created
from either water condensation in the exhaust systems, which causes rust,
or some item hitting the part, such as a rock.   Catalytic converters
should not have any holes.  Some mufflers will come with a small hole at
the rear bottom of the muffler unit.  This hole is there to allow water
drainage.  This hole is usually about 1/8" in diameter, and is located so
that any exiting fumes are carried away from the car.  The pressure that is
within a correctly running car's exhaust system should not be enough to
create a hole.  When an exhaust valve is open, at the time of a combustion
cycle, then that combustion pressure is release into the exhaust system.
This excessive pressure will usually blow apart a seam in a muffler.  This
usually happens when there is a timing problem.  The catalytic converter is
generally stronger than the mufflers, and do not usually blow apart.  You
did not say what size the hole was, or if the hole had rust around it, or
if it was an exploded hole (pressure caused), or an imploded hole (rock
caused).  Yes, keep it plugged, taped, sealed in whatever manner possible,
until you can get it replaced.  Most inspection stations would require
replacement, as repairs to a catalytic converter are not allowed (speaking
as a PA state inspector).

Tex Terry, II
83 5kt sedan (non-quattro)
Franklin, PA  USA