STS Scott Posted July 30, 2004 Report Share Posted July 30, 2004 A few days ago my cat. began to rattle, and has been driving me nuts. Just above an idle, or at cruising speed (1200-1500 RPMs) seems to be the "sweet spot" where is vibrates the most. I have read of the brick inside them going "bad", and causing this rattle, but is it possible something is just loose? I haven't got under the car yet, but was wondering what I should be looking for when I do. Thanks! " ...'took my Cobra down t' the track, hitched to the back o' my Cadillac..." - Jan & Dean, 'hey little cobra' Scott Link to comment Share on other sites More sharing options...
Scotty Posted July 30, 2004 Report Share Posted July 30, 2004 A few days ago my cat. began to rattle, and has been driving me nuts. Just above an idle, or at cruising speed (1200-1500 RPMs) seems to be the "sweet spot" where is vibrates the most. I have read of the brick inside them going "bad", and causing this rattle, but is it possible something is just loose? I haven't got under the car yet, but was wondering what I should be looking for when I do. Thanks! Take a rubber mallet and bang on it, you should hear noise inside it. I had one go on a 91 Seville and it was loud. It sounded like a can with cans inside it. Mike Link to comment Share on other sites More sharing options...
Willie Hank Posted July 30, 2004 Report Share Posted July 30, 2004 Replace it before it gets blocked. Link to comment Share on other sites More sharing options...
bigfoo Posted July 30, 2004 Report Share Posted July 30, 2004 CATs are cheap to replace now.. They used to be 300-400$ long time ago but now you can pick up a high flow one for $89 if you want :> Link to comment Share on other sites More sharing options...
CaddyJack Posted July 30, 2004 Report Share Posted July 30, 2004 Go to Midas...get the lifetime warranty. Link to comment Share on other sites More sharing options...
Arash Posted July 30, 2004 Report Share Posted July 30, 2004 Using a rubber mallet is a good way of testing the cat but it's not allways conclusive. Another sign of a bad cat is excessive whistle when you rev the car at park. I replaced my cat a month ago because I bombed the aircare inspection in vancouver. My Hydrocarbon and NOx levels were way above the limit. I purchased a cat here for $160 can (including tax) and I passed the inspection. Link to comment Share on other sites More sharing options...
CaddyShack24 Posted July 30, 2004 Report Share Posted July 30, 2004 It might be the muffler hangers that are loose, or the muffler is banging into the heat shield. I know my whole exhaust is shot.. rattles like your's does. but i can hear the air escaping. Going to replace it all pretty soon, once i get the idle speed down some and maybe a running rich problem, dont wanna burn it up. Link to comment Share on other sites More sharing options...
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