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exhaust rattle 96 Deville


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Hi all Iseem to have developed a problem with my 96 Deville. I have a rattle underneath at idle and under load.

I have noted that the exhaust pipe is rattling on the crossbar that is between the front and rear doors.

I have replaced the round ring mounts that hold the pipe up just before the brace, and also the muffler mounts.

I also replaced all engine and transmission mounts recently and had this problem both before and after. I noticeed that if I loosen the dogbone mounts and pull the engine forward and tighten the mounts it doesnt rattle as much,

I seem to think the problem might be the flexpipe is starting to seperate on the downpipe before the Catalytic convertor.

Things I know

no broken mounts

no leaks

not any noticeable bent mounts.

Can I get some tips on this.

thanks all

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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The flexpipe is usually very durable and is a good grade of stainless steel so I wouldn't suspect that.

The clearance is pretty tight between the exhaust pipe and the crossmember. It is on the Seville, probably similar on the Deville. You might look into the post catalytic converter oxygen sensor heat shield - it may be contacting the larger heat shield and causing the noise.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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I had a rattle under acceleration on my 91 Seville. Appeared to be a bracket touching the exhaust pipe when the whole exhaust system moved back under acceleration. It was hard to diagnose until I put it on a hoist and asked a friend to powerbrake it. I saw the problem right away and fixed it in seconds by bending the bracket off the pipe.

In your case it rattles at idle, so it would be probably easier to diagnose if you get under the car, but the best way is putting it on a hoist.

By the way, my rattle started after I got off road in a heavy rain.

The saddest thing in life is wasted talent

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I had a rattle under acceleration on my 91 Seville. Appeared to be a bracket touching the exhaust pipe when the whole exhaust system moved back under acceleration. It was hard to diagnose until I put it on a hoist and asked a friend to powerbrake it. I saw the problem right away and fixed it in seconds by bending the bracket off the pipe.

In your case it rattles at idle, so it would be probably easier to diagnose if you get under the car, but the best way is putting it on a hoist.

By the way, my rattle started after I got off road in a heavy rain.

it is that bar underneath, you can actually see where itt is indenting in the resonator. especially under hard acceleration it can be felt. I tried to bend the backet down a little but it didnt help. I thought maybe the flex part of the downpipe was starting to pull down

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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I had a rattle under acceleration on my 91 Seville. Appeared to be a bracket touching the exhaust pipe when the whole exhaust system moved back under acceleration. It was hard to diagnose until I put it on a hoist and asked a friend to powerbrake it. I saw the problem right away and fixed it in seconds by bending the bracket off the pipe.

In your case it rattles at idle, so it would be probably easier to diagnose if you get under the car, but the best way is putting it on a hoist.

By the way, my rattle started after I got off road in a heavy rain.

it is that bar underneath, you can actually see where itt is indenting in the resonator. especially under hard acceleration it can be felt. I tried to bend the backet down a little but it didnt help. I thought maybe the flex part of the downpipe was starting to pull down

I see. Bend the bracket even farther. If it does not help, a hoist is the only and the fastest way to figure out and fix the problem.

The saddest thing in life is wasted talent

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A hoist. I have a rack. I have viewed the full system multiple times, sorry should have specified that.

The only thing about bending the bracket is it seems like a bandaid because the pipe shouldnt hit it unless something is wrong

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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A hoist. I have a rack. I have viewed the full system multiple times, sorry should have specified that.

The only thing about bending the bracket is it seems like a bandaid because the pipe shouldnt hit it unless something is wrong

In my case the bracket got bent (just 1/4" was enough) during the off road accident.

The saddest thing in life is wasted talent

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I absolutely have no idea why I didnt think of that. Tank you so much. last year I hit a pile of hard snow that a plow left across a highway intersection and broke my bottom bumper section and the rubber gaurd behind the bumper. I wonde if that is the problem. Again thank you, I will try it and post my results

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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I absolutely have no idea why I didnt think of that. Tank you so much. last year I hit a pile of hard snow that a plow left across a highway intersection and broke my bottom bumper section and the rubber gaurd behind the bumper. I wonde if that is the problem. Again thank you, I will try it and post my results

The bracket may look far enough from the pipe, but your engine with exhaust system moves back more than half an inch, so that's when it hits the pipe. I am pretty sure that's the problem.

The saddest thing in life is wasted talent

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