Weird sound coming from truck - sounds like a bullfrog under my truck
Aug 17, 2010 | 08:13 AM
#1
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From: Boston, MA area
Weird sound coming from truck - sounds like a bullfrog under my truck
Ok, so there is not really a Bullfrog under my truck , but it sounds like there is under certain conditions.
My muffler is only about 9 months old, and it is a 409SS Super Turbo which is what appears to me to be a private label Walker Sound FX.
http://www.louscustomexhaust.com/ss409.html
The Bullfrog comes out to play when the exhaust is "warm". Not cold, not when the engine and exhaust are up to temp. I notice it when I drive a distance, turn off the truck to, say, go into a store for 10 minutes then fire the rig up to go on home. At this point the exhaust will be cool and is heating up rapidly from the still hot engine. At around ~1400 rpm, I will get a croaking from under the truck, presumably from the muffler. Obviously I can't be in the car revving it up and under the car trying to pinpoint the source at the same time but I suspect it to be the muffler. After a few minutes of croaking as the engine passes up and down through ~1400 rpm, the sound fades away.
My suspicion is that a weld on one of the baffles in the muffler has cracked and is flapping around at certain temps as the metal expands. All cold, no rattle. All hot, no rattle. When warming, rattle.
Anyone have an opinion before I go back to Lou's and ask them to replace the muffler?
Is it possible that the croaking is coming from a Cat? Does a failed cat make a croaking noise? I have no trouble codes at the moment and it has been making noise for at least a couple of months.
My muffler is only about 9 months old, and it is a 409SS Super Turbo which is what appears to me to be a private label Walker Sound FX.
http://www.louscustomexhaust.com/ss409.html
The Bullfrog comes out to play when the exhaust is "warm". Not cold, not when the engine and exhaust are up to temp. I notice it when I drive a distance, turn off the truck to, say, go into a store for 10 minutes then fire the rig up to go on home. At this point the exhaust will be cool and is heating up rapidly from the still hot engine. At around ~1400 rpm, I will get a croaking from under the truck, presumably from the muffler. Obviously I can't be in the car revving it up and under the car trying to pinpoint the source at the same time but I suspect it to be the muffler. After a few minutes of croaking as the engine passes up and down through ~1400 rpm, the sound fades away.
My suspicion is that a weld on one of the baffles in the muffler has cracked and is flapping around at certain temps as the metal expands. All cold, no rattle. All hot, no rattle. When warming, rattle.
Anyone have an opinion before I go back to Lou's and ask them to replace the muffler?
Is it possible that the croaking is coming from a Cat? Does a failed cat make a croaking noise? I have no trouble codes at the moment and it has been making noise for at least a couple of months.
Aug 23, 2010 | 01:18 PM
#3
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Joined: Aug 2010
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From: boston/colorado springs
I would personally take it back to lou's, especially as you have "their" model of muffler and they may or may not have seen this issue before. From your description it sounds like something in there is loose but its hard to tell without getting under the truck and hearing it.
Aug 23, 2010 | 03:35 PM
#5
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Joined: Sep 2006
Posts: 190
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From: Boston, MA area
Don't tell me that. That is what I am fearing. I have heard of cats rattling, but not croaking. You have heard something like that before?
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