Light puttering under idle - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 02-21-2010, 01:27 AM   #1
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Default Light puttering under idle

This is on my 95 Regal, L27. This has been happening for a while now. While the car is in idle, there'* a light puttering sound coming from the exahust, and its repetitive.

http://www.youtube.com/watch?v=1QWi9_2amVY

If you listen for it, you'll hear it during the idle clips. Its a puttering sound that'* very repetitive and predictable. The car pulls hard and has plenty of power, and there aren't any SES codes thrown. It idles decently well and doesn't fluctuate much at all.

Any idea on what this could be? If you put your hand toward the exhaust, you can feel the exhaust blowing bursts of air during the puttering sounds.
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Old 02-21-2010, 01:32 AM   #2
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What do you have for a muffler, and how old is it?
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Old 02-21-2010, 01:36 AM   #3
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Magnaflow straight through muffler. 4-5 years old, 80-90k miles.
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Old 02-21-2010, 07:20 PM   #4
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I would check the exhaust pipe section betwen the exhaust manifold & convertor. If there is a flex coupling, it might have a crack.
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Old 02-21-2010, 08:09 PM   #5
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I agree, that kind of sounds like a exhaust leak. The flex pipe is a good place to start.
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Old 02-21-2010, 09:41 PM   #6
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Quote:
Originally Posted by bobc997615 View Post
I would check the exhaust pipe section betwen the exhaust manifold & convertor. If there is a flex coupling, it might have a crack.
No flex coupling there, but there does seem to be some kind of crack in the downpipe itself right before the cat. I'll do a seafoam on the car and check for leaks, and if there are any, I'll have that checked out at an exhaust shop. Hopefully they can just weld it up for now.
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Old 02-21-2010, 09:59 PM   #7
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You really do need a flex pipe there. The engine moves and will brake the exhaust.
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Old 02-22-2010, 12:12 AM   #8
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You really do need a flex pipe there. The engine moves and will brake the exhaust.
This is the factory exhaust. There'* a flared out pipe that fits onto an exhaust bushing and bolts onto the downpipe, which provides the seal when the engine moves. I've recently replaced that gasket.
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Old 02-22-2010, 12:28 AM   #9
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The stock down pipe is a flex pipe, just looks a bit different. Chances are it'* leaking. Do the seafoam and you should see the smoke coming out of any leaks.
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Old 02-22-2010, 12:45 AM   #10
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The stock down pipe is a flex pipe, just looks a bit different. Chances are it'* leaking. Do the seafoam and you should see the smoke coming out of any leaks.
Will do this week.

One other thing someone mentioned over on w-body.com. They said I had a burned exhaust valve (and guide) and that this engine will now proceed to a downward trend, that its old and tired, and that I should never go past 4000 miles and drive it like a granny.

I laughed. Is that even possible on a 3800? I know it has 213k miles, but I've seen many of these cars go way past 350k if they don't rust before that point.

I was also told that the EGR helps cool down exhaust valves in some way. Not sure how though.

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