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ChrisLx93
New User
Mar 9, 2017, 12:23 AM
Post #1 of 4
(1880 views)
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Noise when accelerating.
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I have a 2006 GMC Sierra. The day before yesterday I was driving and everything was fine. But later that night I went to the store and noticed a sort of knocking sound. Coming from what sounds like the driver side front end. It only happens when accelerating to around 15-25 mph. If I accelerate fast. It doesn't do it, it's only when slowly accelerating It does it in drive. And also in neutral. Once again. Revving engine slowly you hear it, revving engine fast. It doesn't make the noise, does anyone have any ideas? I've heard it could be a heat shield rattling or something like that.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Mar 9, 2017, 1:44 AM
Post #2 of 4
(1876 views)
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Re: Noise when accelerating.
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OK - You say it can do this noise when in neutral means no load on the engine really so heat shield(s) are to be checked, fixed or rules out is fairly easy. You need a rubber hammer is best IMO and tap on exhaust parts right from the tail pipe(s) with engine off a heat shield loose or how fastened broken will make noise then if that reproduces it go find where it's making the noise. Broken/rusted spot welds, wrap around shielding to muffler - all the way forward. Many truck you can get under without hoisting. Some drivetrain layouts there is a bolted gasket under stress can break a bolt? First step is the hammer trick and visual inspection then you can figure out what will fix it or if not found to be any of that move on to other things that can make noise. Heat shields are super common to me, assorted vehicles but this one should have a shield around muffler seems to be first. You didn't state which engine or weight rating, 4X4 or not so can't know layout of exhaust! T
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ChrisLx93
New User
Mar 9, 2017, 4:20 AM
Post #3 of 4
(1866 views)
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Re: Noise when accelerating.
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Right, forgot to mention. It's the Denali Sierra, it's a 6.0 V8. AWD, and after just reading a lot about heat shields and talking to my friend that's a mechanic. He said check heat shields. Because, it making the lose in neutral doesn't concern him with the transmission or anything like that, (hopefully, because I'm trying to sell this truck)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Mar 9, 2017, 4:39 AM
Post #4 of 4
(1864 views)
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Re: Noise when accelerating.
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Don't read about it go check it. AWD just makes the exhaust a bit tighter in spots to avoid the gearcases for the front wheels to drive. If this was the motor loose causing exhaust parts to touch a frame/body part it wouldn't do that in neutral is why I dismissed motor mounts. Engines all vibrate some and are isolated by rubber mounts all the way to each wheel except the exhaust and the shield are just thin metal doing what they must, shielding heat from things and body so heat doesn't burn the wrong stuff. They give out easily with the slightest rust at spot welds and can make some wild noises at just certain vibration levels of the engine and go away. LOOK - I can't do that for you. If you lose 1/2 of a clam shell of the things you are screwed to buying a whole section of exhaust if nothing still there to fix! You won't like the cost of that, trust me. If you can't get under this go have it found now so you know. Some can be fixed some can't, some techs may not fix one rather only replace whole section no matter how good inside still is which can be fine for lots longer. Again - I can't do the looking and testing for a noise - you have to in person or get help if you can't find it and it might not be this at all, T
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