Clanking Catalytic Converter

Hi again guys,
Turns out that the clanking noise I described in the previous thread on chain slap was coming from inside the right catalytic converter of
my 380sl. It's particularly noticeable when I start the car on cold mornings, and dissipates shortly afterwards, as it warms up, for reasons I don't fully understand.
I had a custom mufffler shop put the cat -- - a Walker universal, I think -- on for me about 5 years ago, because the straight pipe system they had made for me was too loud. So, replacing the cat at this point should be fairly easy.
I suspect that something inside the cat, like a baffle, broke off, but why it stops shortly after the car starts running is a mystery. Has anybody seen this before, and does anyone happen to know who makes the best universal cat. At this point, I'm considering Goerlich. Magnaflow, Eastern, and D.E.C.
Thanks very much for any advice anyone can give me on cats, and for the previous responses.
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Sounds like the ceramic inside broke off... this is due to overly rich engine running condition.
Go with Magnaflow and make sure it is the right size... alot of time with like DEC or any aftermarket, they put in a too small cat. Go here to find out which one you need.
http://www.car-sound.com /
Shop on ebay and have a muffler shop weld it in.
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wrote:

Hmmm! Sounds reasonable. My car has been emitting quite a bit of white smoke when I start it up, and after it sits for a while. Could this be due to the rich mixture, too -- as the coolant and transmission fluid levels are normal, and there isn't any water in the oil. OTOH, 3 plugs were oily when I recently changed them. So, I may need valve stem seals, too.
Should I try adjusting the mixture myself and, if so, how? Or should I just take it to a shop with an emissions tester?

Why weld it in, Tiger? If I use clamps, I can cut it out, and replace it myself.
Thanks very much for all the help.
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Fix the valve stem seals first... the oil really does kill the cat. Fuel mixture is easy to adjust too... with a 2.5mm long allen key... on hot engine... adjust counterclockwise 1/8 of a turn at a time... then squirt a tiny bit of carb cleaner into the intake...
What we want is no change or tiny bit rise in engine speed. Clockwise is enrichening... so with a squirt on rich mixture, engine will stumble. Tiny squirt is like quick on off... hardly any stream of cleaner squirt out... hard to explain... it is not like we are trying to flood the engine with cleaner... just a squirt.
Clamp is fine too... weld is better.
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