strange noise...driving me CRAZY!

[Silver35thZ]

ok i think i posted about this awhile ago, but i never solved the problem. ever since i got my cut out installed theres a weird noise towards the back of my car...like right under the trunk area near the axle. it sounds like a freaking loooud vibration, inside the car you can hear it loud and if you stand outside you can hear it as well, but it sounds different i guess inside it sounds more like a drone than from the outside. i've looked under my car and find nothing wrong, i've taken it to the exhaust shop where the cut out was installed and asked them to lift it up and look and they found nothing. the noise usually happens when i'm running low on gas and it usually happens when i'm in lower gears like first taking off like 1-3 and reverse. also it happens at idle when i first turn my car on sometimes and its sitting there and then bam the sound comes on and goes away and then comes back and then goes away. its weird...this is why i'm thinking about gettin a catback installed on my car...just looking for a good deal. i've put up with this noise for awhile...i've had the cut out on for a year already but its slowly driving me crazy! pleaaaaaase help me out

[Greg Norris]

fuel pump maybe?

[Silver35thZ]

do i need to replace it or do you think it was damaged when they installed the cut out...because this is my thinking...i got my flowmaster muffler put on at a professional exhaust shop and then the cut out put on at this place where it was cheaper and they are an exhaust shop...but not as professional, like they do good work but i dunno, its a bit shady. but when they cut off my existing piping to put the cut out they didn't put clamps on the exhaust so when they cut that chunk out my catback just swung down and was being supported by the over-axle part and it was just hanging there and then they put those holders that are like jacks to hold up the piping in place while he welding the cut out in place. i'm thinking something went wrong there...the exhaust doesn't hang or dangle, its all in its place but the darn noise is driving me crazy and i have no idea what it is

[Greg Norris]

turn your car to "on" but dont start it. make sure the radio is off, and listen to the sound. is that what you are hearing?

[Silver35thZ]

nope, no noise. only happens when the engine is on. like i'll start her up and she will idle for a little bit and then the noise starts. the noise will come on like 8 or 9 times out of 10 when i start her. and when i'm driving at low speeds generally reverse or 1-3, like going into 3rd or neutral it happens.

[94greenbandit]

Are you sure it is from the rear. Seems kind of odd that you would hear it from just idleing unless it is your fuel pump but I wouldn't think it would make that much noise.

[StripedZebra]

It almost seems obvious that your exhaust is rattling on something...but maybe im wrong...? Keep in mind that you cant jack the car up to look around (unless you lift from the axle) because that will alow the axle to sag and that could be the problem (exhaust rattling on the axle).

[Silver35thZ]

see thats what i was thinking, because i had suspecion that it was a clamp over the rear axle and that when i'm low on gas the back end doesn't sag as much so it rattles with something...i dunno, the exhaust shop said they couldn't find any problem. and when i was in the accident and had the rear bumper repainted and berger panel done i told them about the noise and they said they heard nothing, because they drove it around and found no problem but the car had the exact same miles when i picked it up as when i left it so i don't think they drove it...liars! if i got a new catback would that solve my problem, i guess thats what i'm gettin at

[jblindy]

Cab you squeeze under the rear of your car and see how close the exhaust is to your axle. The point of the exhaust where it goes over your axle. Is there any part of your exhaust that is touching underneath your car?

[Silver35thZ]

i've gone under my car before and checked and didn't see any problem spots but that was before i had an idea of what the problem might be. i will have to go under the car again, but i think its gonna have to be this weekend cuz me and my dad just did a full tune up on his truck and after gettin all dirty i came in and took a nice shower so i don't feel like crawling under another car haha i will go under it this weekend for sure though and find that darn problem, i'm thinking about buying a catback and having it put on by a professional. i've already pmed someone here on the forum about a price quote

[00SSvert]

Could be a U-join. Very unlikely it'd be making that much noise, but possible.

Maybe the gas tank is loose and only rattles when almost empty or when your drive train is at a certain RPM.

Or maybe a loose bracket from the accident.

(we'll look at it if you haven't figured it out)