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1999 Cadillac Deville
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14 Posts
Discussion Starter #1
Had a rattling noise under the car which sounded like a heat shield to me. Mechanic tells me the catalytic converter needs to be replaced and it is the source of the rattle. The price seemed way out there. Has anyone replaced theirs and how much did it cost? Also, does the car come stock with one catalytic converter or is there more than one? Thanks in advance.
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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26,323 Posts
One cat. A walker or Eastern replacement is what most here will recommend. What were you quoted?

No check engine light/cat inefficiency code?
 

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1999 Cadillac Deville
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14 Posts
Discussion Starter #3
Thanks for getting back to me. Quote was $1,500, no codes or lights yet. Just a rattle/buzzing noise. Im not convinced and I'm thinking of getting a second opinion.
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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$1,500 is insane. That's probably for a factory replacement, which is the entire exhaust system, including the cat, in one welded together assembly.

How did he come to the conclusion that it's bad?

When does it make noise?
 

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1999 Cadillac Deville
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Discussion Starter #5
Car makes a rattling/buzzing noise underneath the car when idling or coasting after its put in gear and rpms drop a bit. Can't hear it when accelerating or on the highway. I thought $1,500 was loco too.
 

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98 DeVille, 97 DeVille d'Elegance
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Holy crap Batman.. Thats a major league rip off. A rattle doesn't mean it's bad, maybe shield is loose.
 

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1999 Cadillac Deville
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14 Posts
Discussion Starter #7
I thought it was the shield too. That's what it sounds like to me. Car is running beautifully and only has 74,000 miles on it.
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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26,323 Posts
If it's making the noise in gear only, it could be a motor mount or exhaust hanger issue, allowing the exhaust to contact the body.
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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19,270 Posts
Thanks for getting back to me. Quote was $1,500, no codes or lights yet. Just a rattle/buzzing noise. Im not convinced and I'm thinking of getting a second opinion.
==================================
if you DO need a new cat -
and you do NOT live in the Peoples Republic of California -
EASTERN CATALYTIC 50282 - $155 - including shipping -
http://cart.carparts.com/basket?ai=true
 

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1992 DeVille
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2,339 Posts
pjbull said:
Car makes a rattling/buzzing noise underneath the car when idling or coasting after its put in gear and rpms drop a bit. Can't hear it when accelerating or on the highway. I thought $1,500 was loco too.
Loco is spot on. I'd get a buddy to keep the car in the rattle state while you look under to see what's up. Just be safe. Block the tires and use common sense.
 

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1991 Cadillac Sedan deVille
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591 Posts
Could be your catalytic converter. They start to rattle when the bricks inside start to break down. My original one started rattling last year, and I replaced it myself. I got Eastern Catalytic for less than $50 with the shipping.

For your Cadillac I found Walker, part #93304, from PartsGeek for $138.18 including the shipping.

To make sure it's the catalytic converter, jack the car and support it (make sure the engine hasn't been run prior), then start hitting with your hand around the exhaust and the catalytic converter itself. See if you can duplicate the sound. If you can, look for anything loose that could be vibrating and causing the noise. Also, use your ear to try to pinpoint the source. If you don't see anything loose, then you'd know for sure it is your catalytic converter.
 

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1999 Cadillac Deville
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14 Posts
Discussion Starter #12
Thanks everyone. I questioned the shop about the cost and they came clean and told me that they only install a complete system with the exhaust. I said that's loco since there is nothing wrong with the rest of the components. They told me I could go to Meineke or similar chain to do the converter only but that the car would not like it and that it would start throwing error codes. I would expect that Meineke or similar chain shop would stand behind their work with some kind of warranty. Anyone have experience replacing just their converter and did you wind up with error codes a few months later? Thanks in advance.
 

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1992 DeVille
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2,339 Posts
pjbull said:
Thanks everyone. I questioned the shop about the cost and they came clean and told me that they only install a complete system with the exhaust. I said that's loco since there is nothing wrong with the rest of the components. They told me I could go to Meineke or similar chain to do the converter only but that the car would not like it and that it would start throwing error codes. I would expect that Meineke or similar chain shop would stand behind their work with some kind of warranty. Anyone have experience replacing just their converter and did you wind up with error codes a few months later? Thanks in advance.
They're full of crap. As long as it's the proper replacement part cat for your car, you should be able to just swap it out no problem.
 

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98 DeVille, 97 DeVille d'Elegance
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Find another shop as the are straight up lying to you. A replacement convertor will not cause issues or throw codes.
 

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1999 Cadillac Deville
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Discussion Starter #15
Thanks everyone. The old crap detector went off when they were trying to tell/sell me all of this. I appreciate all of your comments
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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In my experience, and experience of friends/family, chain exhaust shops suck. An independent exhaust shop is the way to go.

Cheap aftermarket converters simply don't have enough precious metal catalyst in them. They're not efficient enough, and will trigger codes (as yours should be doing if it's bad). An Eastern or Walker won't cause this issue.
 

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1990 Fleetwood / DeVille FWD/2015 SRX PERFORMANCE/2017 XT5
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Re: 1990 Deville / FLEETWOOD FWD catalytic converter noise

Hello I am hearing a similar issue which is posted on this thread. Car makes a rattling/buzzing noise underneath the car when idling or coasting after its put in gear and rpms drop a bit.

I have no error codes and wondering if it's best for me to buy a catalytic converter on eBay and if so what is recommended for the 1990 Front Wheel Dr., Deville Fleetwood. Living in Nevada.

Since I purchased this car I have noticed a strong odor of gasoline at times and there has been water coming out of the exhaust pipe recently not a lot but enough to notice. The car is currently being worked on in many different areas and of course this problem was noticed recently.

Once I know what to buy I have to find someone willing to install a purchased part. I thought perhaps Meineke mufflers might do it.

Your advice on what needs to be purchased and what needs to be checked prior is highly appreciated.

I keep hearing about a heatshield but I'm not aware of what that is. Where it is, how to check it etc. I rather not get under the car Which is lifted as I have a terrible back.
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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Based on your last sentence, take the car to a good independent custom exhaust shop (NOT Meineke or any of the other chain shops). They can easilly diagnose a bad cat, loose heat shield, bent pipe or sagging/broken hanger causing the exhaust to contact the body..... The diagnostic is usually free.

Heat shields are just that. They're bolted to the underside of the car, above the converter, sometimes above the muffler, or anywhere else the exhaust is very close to the body of the car.
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Cold/cool exhaust systems drip condensation - normal. One reason why our mufflers have weep holes in them - my Seville piddles two streams of pure water onto the garage floor during cool weather start/back out. (So does the Explorer and/or F-150)

Have your exhaust shop check that the muffler weep holes are clear.

Heat shield - preheat your oven to 400 degrees. Open the door and place a flat hand so as to feel the heat. Now place a page of tinfoil between your hand and the heat source. Heat shield.
 

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1990 Fleetwood / DeVille FWD/2015 SRX PERFORMANCE/2017 XT5
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Thank you for your response, what catalytic converter do you recommend for this car?

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When I was working on the lighting for the car on the inside before I discovered that the BCM had a loose connection the floor in the middle of the car became very hot almost to the point of burning my arm and this is inside the car. Once the BCM connection with tightened the car started running normal and that didn't happen again I don't know if it's related to the heat shield.
 
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