What's in a catalytic converter

Cliff R · Post by **Cliff R** » Sun Jan 29, 2012 1:44 pm

When I bought my L series I noticed the hot air stove pipe outlet off the shroud around the catalytic converter was rusted off. The shroud was there but the outlet/spiggot was missing so I couldnt put the hot air stove pipe on.
I went up to the wreckers and bought a front exhaust section from a 93 L series and put it onto my car. This car had more Ks but was still OK and my only local option.
I now have an loud rattle that originally (and may well still be the case) coming from the exhaust shroud/cover that is around the final, rear section of this front exhaust section between the catalytic converter and the flange before the hot dog muffler that is roughly level with the gear stick and on the 2nd part of the exhaust. this rattle is very obvious on gear changes and when coasting. It is not the clutch or release bearing either. It is definately a part of the exhaust. I have tried tapping parts of the exhaust with a rubber mallet and this is how I found the loose shroud part.

I am wondering what is in a catalytic converter and are there components that could rattle. ?

P.S. being a glutton for punishment I have now taken all the shrouds off my original front section of exhaust. This took everything from a socket to a blowtorch but they are now all off.
What are these shrouds for, protecting the exhaust from damage, heat distribution to protect the car and/or CV joints or both. Do I need them ?
If there is nothing loose in this front section of exhaust I will go looking at the hot dog.

littlewhiteute · Post by **littlewhiteute** » Sun Jan 29, 2012 2:46 pm

You have fitted a catalytic convertor that has had a meltdown in the last car, probably from excessive misfiring.

The heat shields are necessary to keep the exhaust heat of the convertor (about 600 degrees C) away from the rest of the car.

YouTube · Post by **El_Freddo** » Sun Jan 29, 2012 9:05 pm

Q: What's in a catalytic converter?

A: Some exotic metal that costs a pot load of money, hence the cost of a new cat - and the reason why you can get a good deal on a used cat converter...

Cheers

Bennie

Gannon · Post by **Gannon** » Sun Jan 29, 2012 9:32 pm

The local wreckers want over $100 for a used commodore cat, I bought a brand new one, 2.5" in and outlets for $140

steptoe · Post by **steptoe** » Mon Jan 30, 2012 8:07 am

and used worth about $15 each as scrap - scrap them separate to any other metal you have.

Some , have absolutely nothing in them

Cliff R · Post by **Cliff R** » Mon Jan 30, 2012 5:34 pm

Well this is different.
I am writing this on my nintendo dsi.
Small screen makes things hard to type but otherwise not too bad...
Had a bit of a look today and a listen with a stethoscope and I think the noise is coming from the middle muffler/hot dog. I dont think it is the cat. Dont really feel like pulling anything apart at the moment so things will have to wait.

thunder039 · Post by **thunder039** » Mon Jan 30, 2012 6:50 pm

cliff r wrote:well this is different.
I am writing this on my nintendo dsi.
Small screen makes things hard to type but otherwise not too bad..

ha!:-d

alang · Post by **alang** » Fri Feb 03, 2012 11:16 am

i had a cat go on the holden jackaroo i use to own out in the middle of no where. it stop the exhaust flow and reduced my movement couldn't go over 40kph. so i removed the section of the car and couldn't see light through it. it made a noise when shaken so i found a star peg fence post and drove it through the cat smashing the white ceramic honey comb piece out from inside. i replace it back on car only to find that the old girl hadn't sounded or gone that good in years never did replace it i traded it in on a 4Runner insteal.

Post by **TOONGA** » Sat Feb 04, 2012 8:37 am

steptoe wrote:and used worth about $15 each as scrap - scrap them separate to any other metal you have.

Some , have absolutely nothing in them

minimum of 40 dollars now for a complete cat.

as for what is in them they vary,

http://en.wikipedia.org/wiki/Catalytic_converter

how they work?

http://auto.howstuffworks.com/catalytic-converter.htm

TOONGA

Bungers · Post by **Bungers** » Sat Feb 04, 2012 8:49 am

Yep i smash all my cats out. Did it to my old STi's, done it on my current Evolution VII, about to do it to both my 88 Brumbys

RSR 555 · Post by **RSR 555** » Sat Feb 04, 2012 4:11 pm

El_Freddo wrote:Q: What's in a catalytic converter?

A: Some exotic metal that costs a pot load of money, hence the cost of a new cat - and the reason why you can get a good deal on a used cat converter...

Cheers

Bennie

Platinum or Rhodium... both very expensive/precious metals

steptoe wrote:Some , have absolutely nothing in them

o WTF??? really? who would do such a thing

Cliff R · Post by **Cliff R** » Sun Feb 05, 2012 9:46 am

Went to the extent of pulling the cat I bought from the wreckers off the car, took off the stove pipe shroud, put this onto my original cat and put this all back on the car.
Noise is still there so unless they are both stuffed I will have to look at the hotdog in the middle. Looking up the exhaust into the hotdog the centre section is all Ok but a tap with a hammer seems to produce a rattle somewhere inside the hotdog inself.