Cat making funny noise
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Freshman User
Joined: Mar 2005
Posts: 38
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From: TN(Nashville/Chattanooga)
Cat making funny noise
Hey guys, wondering if anyone might have any helpful info for me-
Seems like something inside my catalytic converter is rattling. It mostly occurs at idle, though it's not all the time. Just frequent enough and loud enough to make me wonder. It almost sounds as if there's a pebble or something caught in there that rattles against the walls, making a pretty obnoxious metallic sound. This just started happening a couple days ago. It's on a 1985 F-150 with the 300 straight six, original exhaust equipment (except the previous owner did a dual tip cat-back job on it). The underside of the cat says "Catco" on it. Is this something I should be concerned about? It didn't make the sound at all on the commute to/from work today, but yesterday it would rattle every time I came to a stop. It doesn't seem to be very consistent. Any help will be appreciated, thanks in advance.
Seems like something inside my catalytic converter is rattling. It mostly occurs at idle, though it's not all the time. Just frequent enough and loud enough to make me wonder. It almost sounds as if there's a pebble or something caught in there that rattles against the walls, making a pretty obnoxious metallic sound. This just started happening a couple days ago. It's on a 1985 F-150 with the 300 straight six, original exhaust equipment (except the previous owner did a dual tip cat-back job on it). The underside of the cat says "Catco" on it. Is this something I should be concerned about? It didn't make the sound at all on the commute to/from work today, but yesterday it would rattle every time I came to a stop. It doesn't seem to be very consistent. Any help will be appreciated, thanks in advance.
Posting Guru
Joined: Nov 2004
Posts: 1,137
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From: Asheville, NC
I put aftermarket cats on my '83 w/351W. One started rattling and buzzing. My exhaust guy said that the heat shield was loose and he spot-welded it. No noise since.
My old cats were subjected to incredibly RICH fumes for a long time. After I got the problems straightened out, the cats were shot and stopped up. They rattled and buzzed. I guess the cat material inside rotted away somehow. They were on the truck for 36k.
My old cats were subjected to incredibly RICH fumes for a long time. After I got the problems straightened out, the cats were shot and stopped up. They rattled and buzzed. I guess the cat material inside rotted away somehow. They were on the truck for 36k.
Senior User
Joined: Jun 2003
Posts: 390
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From: Rose City, MI
it sound to me like the insides of your cat is broke which can eventually plug up your muffler and lead to some problems. Catco is an aftermarket cat manufacturer as a matter of fact i had to change one out today at work that was just over a month old.
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Freshman User
Joined: Mar 2005
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From: TN(Nashville/Chattanooga)
The truck doesn't have mufflers, the pipes just go straight out the back from the cat. I guess I had better get it replaced before emissions testing time rolls around again. Is there a chance of backpressure sucking whatever's loose up the manifold? If I had my druthers I'd chop the thing off throw some headers with a couple flowmasters on it. Oh well. Thanks for the info, guys.
Senior User
Joined: Jun 2003
Posts: 390
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From: Rose City, MI
Since you have emissions testing putting headers on will not make the cat sitiation any better you will still have to have it. If you put true dual then unfortunatley you will have to have 2 cats. if you could get away with out it i would recomend gettin rid of it and putting a muffler on. I run a single in dual out flow on my truck and it sounds pretty good i also have 18" long 3.5 in echo tips on it right now. gonna change it up here in a couple of weeks. I am thinking about running a stainless imco chambered muffler and some 22" echo tips.
