My experience with a couple of OEM cats is they slowly disintegrate. They are a ceramic honeycomb of small straight through holes.  Either they plug up from big pieces going sideways or the break into small chunks that are eventually pulverized in the muffler and blown out as expensive dust.  The cat in my '85 had about 1 1/2" of the core left and a golf ball size piece rattling around inside. Soon it would have emptied itself.

Stuart

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Neil N
Sent: Sunday, July 02, 2017 4:02 PM
To: vanagon@GERRY.VANAGON.COM
Subject: 2.1 Ernst Muffler Design and Failing Catalytic Converter

Hi all.

Several archive and google images searches didn't bring an answer.

Is the Vanagon 2.1 Ernst muffler basically a straight through design?
Or does it have baffles and sets of pipes redirecting exhaust flow?
When a cat element fails, do the pieces usually get blown out the tail
pipe?

On a trip in the Baja, the generic cat (likely Walker) on my Jetta 2.0
started to sound like it had several ball bearings bouncing around
inside it. The noise abated fairly quickly but I'm certain the sound
was caused by the cat element finally breaking into pieces. I'm
wondering if any of those bits could get caught in the muffler or if
they just blew out the tail pipe.

Neil.

--
Neil n

Blog: Vanagons, Westfalia, general <http://tubaneil.blogspot.ca>

1988 Westy Images <https://picasaweb.google.com/musomuso/New1988Westy>

1981 Westfalia "Jaco" Images, technical <http://tubaneil.googlepages.com/>

Vanagon-Bus VAG Gas Engine Swap Group <http://tinyurl.com/khalbay>