Now im not sure.When i start my venge....98ES, it sounds like there is an exhaust leak up by the motor.Really pissed me off because i just got the exhaust patched in two spots in the rear of the car earlier this year.
The thing is after its running for awhile the sound i thought was an exhaust leak goes away.What the hell?Any ideas?
The only thing i had even remotely close to this sound was in my grand am i had awhile ago, only the sound never disappeared like it does in my venge.The problem with the grand am was a head gasket, any help would be great.
Im sitting at 119,000 miles right now.I need new belts(owner before me never changed them ever), driver side wheel bearing, pads rotors.....im going to go down to see how much all this is gonna cost me to have done later today.If anyone has ever had this prob and knows what it is id like to have a clue before i talk to the mechanic.Thanks in advance!!!!

 

that would be my guess is a gasket... im thinking since the headers get very hot maybe the sound is going away because the heat it softening the gasket causing it to expand and when it cools it returns to normal state. id get the gaskets checked on your headers, might be so

 

Ok that makes sense....a friend of mine said it could be the "donut gasket".Not sure if thats the same gasket or not.

 

Someone else told me it could be a crack in the exhaust manifold.....with basically the same thing happening with it heating up and swelling so its not as loud when its been running.

 

Either are possibilities ... I've even seen the mounting points have a crack and warp when heated

 

yeah the big thing to remember is the tempature the headers and exaust get, average is said to be 1200-1300*F sometimes a little higher and some cases it may run a little lower... either case, that is hot. if your exaust is made from stainless steel... the average melting point is 2650*F so with it being half way to the melting point there is gonna deffinatly be some expanding with the heat, and shrinking when it cools, it could really be anything, cracks, gaskets, or even warped exhaust, or warped headers. I could see any of these happening over time of the constant heat and cooled, let me know what you find out im curious to find out what happend... also check the welds... alot of time welds will only hold for soooo long depending on the skill of the welder. if i were you id try to find some high boiling point liquid and go with the same process of checking for a leak on a tire, spray it all over the exaust, gaskets, welds, and headers.. if it bubbles or blows off... you know where the leak is... im just not sure what liquid you could use at them tempatures

 

I just had the exact same symtoms as you and thought it was the rear exhaust manifold. come to find out after hooking up a smoke machine the small piece of flex pipe that runs under the engine was rusted out on one end. don't know how it closed up after heating up but if i were you i'd check that location out.