RE: 9020V Catalytic Converter Noise

[Frank Martin <fmartin@mr.oa.ithaca.edu>]

**Sorry if this is a re-post...I sent it, but didn't see it show up on the 
Qlist...

>------------------------------
>From: Peter Tracy <pgt@ekbos.com>
>Date: Sun, 23 Mar 1997 16:23:26 -0500
>Subject: 9020V Catalytic Converter Noise
>
>I've been hearing this raspy noise sounding like a loose heat shield
>coming from my exhaust system for a while and decided to look at it this
>weekend. Turns out that it seems to coming from inside the catalytic
>converter and can even be heard at idle if you are outside the car.
>Also, if you hit the side of the converter with your hand with the
>engine not running, you can hear what seems to be something loose in
>there.
>
>Anybody ever seen anything like this before? Does it mean I need a new
>converter? Seems strange because the car only has 40K miles on it.
>
>TIA.
>Peter
>
This sounds *exactly* like a problem I had with an '80 VW Rabbit.  An 
occasional rattling noise from under the car, which I traced to the *inside* 
of the catalytic converter (using the old flesh & bone hammer (fist)). Another 
symptom was that the car would, while underway, inexplicably (isn't that 
usually the case?) lose all power, and not run at all above idle. I took off 
the cat., and found that a chunk of the substrate was rolling around loose in 
there....it had been nicely rounded into the exact size and shape of a medium 
egg. What was happening was that this chunk would occasionally roll up and 
block the back end of the converter. (I would have said "block the back end of 
the cat," but have seen some of the retorts on this list.) With a little 
knock, the chunk would roll back down and the car would run fine.  

No way around it: if this is the case with your car(s), you'll need to replace 
the converter. Of course, do check all the outside straps/connectors/etc. 
first. (Well, back when I had this 100K+mi. VW and was less environmentally 
conscious, I simply whammed out the rest of the substrate with the end of a 
tire iron (being the high-tech.-tool guy I am) and re-installed it.)

Frank M.
'89 100Q
'88 Mazda 323 GTX