: Rattling catalytic converter on n*



Andrew M. Franklin
05-26-05, 07:40 AM
There seems to be a rattle under my wife's 94 deVille N* - especially when the car is parked and idling there is a general tinny rattle near cat. Is it possible the element is loose in the housing? Is this common? Is there a way to repair this? Thanks. Sincerely, Andy.

mcowden
05-26-05, 10:53 AM
It might just be the heat shield rather than the internals of the converter. They can work loose or a support can rust away and they need to be fixed. That would be easy. If the internals of the cat are broken and rattling, the only repair is replacement. Any muffler shop should be able to tell you which one it is, as long as the rattling will happen when you take it in there. If it doesn't rattle while you're driving, my money's on a loose heat shield. I have the same problem and just haven't been motivated enough yet to crawl under there and fix it.

Jack Ammann
05-26-05, 05:13 PM
Hi Andrew...My "cat" took a dump a few thousand miles back on my '94 ETC. I just got me a straight tube that fit with the appropriate flange, took the cat off and put the tube in....and wa la...I had more horse power according to my "Butt" dyno...LOL...and all that rattling was gone :D

vision864
05-26-05, 05:37 PM
I had the same thing happen to my 93' turned out it had just caught a rock and busted the material up inside it, if you can straight pipe go for it, an aftermarket universal for mine cost 300 bucks

mcowden
05-26-05, 10:51 PM
You certainly can put a straight pipe in the place of the cat and maybe get a little more power out of it, but realize that the exhaust will smell like gas, it's illegal, and you'll never pass an emissions test. An OEM-style replacement is $162 approximately plus installation. I would still have a look at the heat shield before you do anything with the cat.

tco43
05-28-05, 10:40 PM
It is rare, but it does happen that the inner element of the catalytic converter separates itself from the shell and then gives off this obnoxious rattle. You can stop the rattle. Drill a small hole in the bottom of the shell to put in a sheet metal screw that will pin the element in one place. Make sure the hole is small enough that the screw is a tight fit. Cut off the point of the screw to a blunt end so it will not penetrate the element. It might take more than one or two screws, but it will work.

strabo40
05-29-05, 06:10 PM
I had the same problem with my '92 deVille. While the car sat still idling, there was a rattling noise that drove me crazy. I thought it was a loose exhaust pipe, but could not pin point it. I finally took it to a shop and found that the catalytic convertor was bad, so I had it replaced for around $290. They showed me the old convertor and you could shake it like a baby's rattle and make plenty of noise. The car does not rattle anymore, plus the car has better response and seems smoother.

peteski
05-29-05, 11:22 PM
I had this happen to my 93 Eldo. I drove it for about a year until the sound got so awful while I was at the traffic lights that I decided to do something about it. A nice Caddy making such an awful noise! No good!

It also rattled when I gunned the engine.

I took it to Mineke (sp?) last year and they agreed that the Cat was bad. I got it replaced. We looked at the old one and the catalist brick wasn't visibly broken but it was loose in the housing.

No more rattles!
:thumbsup:

Peteski

rockytfox
07-02-05, 05:11 PM
Can a broken element in the catalytic convertor block air flow and create sluggish acceleration?

Ranger
07-02-05, 05:49 PM
Yes.

mcowden
07-03-05, 12:58 AM
Can a broken element in the catalytic convertor block air flow and create sluggish acceleration?

Ranger is right. It can absolutely kill your acceleration. Replace the cat.

rockytfox
07-13-05, 01:43 AM
I'm thinking about just using a straigh pipe for awhile. Does anybody know of a good replacement cat that wont go out in a year?

mcowden
07-13-05, 12:06 PM
I'm thinking about just using a straigh pipe for awhile. Does anybody know of a good replacement cat that wont go out in a year?

You can get a WALKER Part # 15815 direct-fit (not universal) catalytic converter for $140 at www.rockauto.com.