Strange noise...

[S1nemesis1s]

I know its next to impossible to diagnose noise over the internet without a good example – maybe I will make a video if I can ever get the time.

When I first start my Tahoe I can hear a loud grumbling in the back, it sounds like vibration but also a grabbing noise. Does this sound like anything someone has had before?

I had a new muffler put on, wondering if that might be it. The back brakes have been totally done, so don’t think that’s it. Not sure. Any thoughts?

Thanks guys!

 

[iamdub]

You mean when you first start it after sitting (cold start)? Mufflers, especially aftermarket ones, can change sounds as the cool metal inside them is suddenly hit with hot exhaust. Usually it makes a "pinging" sound.

Or maybe it's just the sound resonating and you only hear it after a cold start because the engine is cold idling around 1000+/- RPM. That RPM with no load may cause a particular resonate frequency.

Does the sound change if you slightly blip the throttle and/or hold the brake and put it in gear and/or after it's warmed up and the idle drops? What muffler did you have put on? What's a "grabbing" noise?

 

[S1nemesis1s]

You mean when you first start it after sitting (cold start)? Mufflers, especially aftermarket ones, can change sounds as the cool metal inside them is suddenly hit with hot exhaust. Usually it makes a "pinging" sound.

Or maybe it's just the sound resonating and you only hear it after a cold start because the engine is cold idling around 1000+/- RPM. That RPM with no load may cause a particular resonate frequency.

Does the sound change if you slightly blip the throttle and/or hold the brake and put it in gear and/or after it's warmed up and the idle drops? What muffler did you have put on? What's a "grabbing" noise?

Thank you for the response! Its like a resonating noise, almost grumbling. I just had a single exhuast put on, a magnaflow supplied at this shop. They mentioned cutting out the y-pipe so it is a straight shot. The sound goes away then comes back after I blip the throttle, when I put it in reverse it makes it for a little bit then seems to stop. However, if the truck has been sitting for more than 30 minutes it will do it again. It continues to sound the same when I put it in reverse with the brake on and back out. I thought it might be the brakes grabbing too hard or seizing, but all the parts are new and the wheel spins fine. Its like a low gutteral rattle rather than grabbing noise. I am just unsure are this point. I thought maybe the muffler was rattling in a bracket but it doesn't do it when driving. Its sort of like a "wommmp, wooompp," sound.

I will try and get a video or recording of it and post it.

 

[iamdub]

If it does it when sitting still, then that obviously rules out the brakes. It's really sounding like it's just resonance from the new exhaust. While it's idling and making the sound, crawl underneath it with a pry bar and move the exhaust around. Listen to see if it's louder anywhere in particular then brace the pry bar against the frame and use it to move the exhaust one way or the other to see if the sound changes. Another thing- I recall reading of some Magnaflow mufflers being defective and having their internals come loose and rattle. Just something else to investigate. It may not be anything loose and just be a certain sound frequency that is emitted when the muffler is cool and your ears are more sensitive to it.

 

[rockola1971]

Power Steering Pump. Check your fluid level. Turn hard left then hard right while sitting still and see if that makes it act a fool and show its ugly head.

 

[S1nemesis1s]

Power Steering Pump. Check your fluid level. Turn hard left then hard right while sitting still and see if that makes it act a fool and show its ugly head.

Man I hope not! I just changed thee fluid about 2 weeks ago, been keeping an eye on it since. Seems to turn well. I will see if I can get a video in the morning. Thanks so much guys!

 

[S1nemesis1s]

The noise was the tailpipe vibrating against the body! I swear, you cannot get good work done! It was so sloppy! I took it back and they fixed it to my satisfaction. Man the repair industry has some snakes in it.

 

[MrBalll]

The noise was the tailpipe vibrating against the body! I swear, you cannot get good work done! It was so sloppy! I took it back and they fixed it to my satisfaction. Man the repair industry has some snakes in it.

Hey, if they can get it done in twenty minutes and charge you an hour for labor why not. How some places work.

 

[S1nemesis1s]

Hey, if they can get it done in twenty minutes and charge you an hour for labor why not. How some places work.

Very true.

 

[rockola1971]

I know its next to impossible to diagnose noise over the internet without a good example – maybe I will make a video if I can ever get the time.

When I first start my Tahoe I can hear a loud grumbling in the back, it sounds like vibration but also a grabbing noise. Does this sound like anything someone has had before?

I had a new muffler put on, wondering if that might be it. The back brakes have been totally done, so don’t think that’s it. Not sure. Any thoughts?

Thanks guys!

So what you are saying is you dont like "strange"?