Rattle - suspect CAT

[tikw2124]

Hi all. Just thought i'd pass on my recent experience. last week, a rattling noise began emanating from the engine bay. Took onto indie and while watching him, he hit the forward Cat with a hammer shaft and it seemed to rattle loads. So, the Cat was suspected (£650 + fiiting). Took car in yesterday and good news, the bracket holding the Cat on had fractured. He welded it back on (Cat had to come off) and confirmed the Cat was good. So, before you go buying a replacement Cat, ensure the noise isnt just this bracket broken.

 

[wemorgan]

he hit the forward Cat with a hammer shaft and it seemed to rattle loads.

So you're saying that your perfectly good cat is now less good having being hit with a hammer?

Good to hear it was a cheap fix though.....I'm not looking forward to the day my cat dies.

 

[tikw2124]

So you're saying that your perfectly good cat is now less good having being hit with a hammer?

Good to hear it was a cheap fix though.....I'm not looking forward to the day my cat dies.

Good thought, just as well i recorded the event for future claims, if only!!!

 

[grober]

The down pipes on the w124 are often sheathed with thin metal heat shields. The idea of this is to aid catalytic-converter warm up. These thin metal tube-like structures are crimped/tack welded to the main exhaust pipes. As they corrode they get slack and give off a characteristic "ringing/rattling" noise.
VERY common fault in Merc of that age. They can be quietened for a time by suitable application of jubilee type clips. I would think of changing your indie to someone with a bit more familiarity with these cars?