Subject: 2004 Durango Limited V8 w/o hemi, exhaust leak sound only when starting motor.

After 144,000 miles and NO complaints, this new sound started 4 days ago.
Upon starting the engine, it sounds like a loud exhaust leak to the rear of the motor, then within 30 -45 seconds the sound is gone.
Any ideas?

 

THe gaskets on the manifold may need replaced,
FF

 

Welcome to DF
With engine still cold.try to move the heat sheilds on both sides. If they move,then you have broken exhaust bolts. They would need to be replaced.

 

Thanks for the quick replies. I waited until cooled, and checked the heat shields. Solid. No movement. Thanks for the suggestion!
So I tried again to listen closer to the sound. Hood up, I turned the key over, and gave it no throttle. The "exhaust leak" sound was there, drivers side, rear of motor, low. Then approx 30 seconds in, the motor idled down, it sounded as if something " closed", and the sound faded away. I gave some throttle, no exhaust leak sound.
I had motor on maybe 2-3 minutes. Turned it off, then quickly back on, and the sound isn't there. So it's happening at cold start only.

Thank you,
Steve

 

Steve:

Your symptoms are classic for an exhaust leak. Specifically an exhaust manifold issue of some type.

The 4.7 motor is well known for these as time goes by. Can be a cracked manifold or broken/loose manifold bolts.

If you can live with the noise, it will not hurt anything. Myself, it would bother me just knowing that things weren't right.

Easy access to either side can be had by removing the inner fender liner on the offending side.

Don

 

The first generation Durango section has a few threads about the 4.7L studs breaking. This seems to only happen in the 4.7 as far as I know,
FF

 

If its the exhaust manifold gaskets, whats an "average" price range I should expect to pay?

Thank you

 

Fel-pro has a set for the 4.7L for $14.00,
FF

 

I should have asked, How much to have them installed? My days of working on vehicles stop in the 80's, on the cars from the 60 and 70's!

Steve

 

Most mechanics in my area charge $65.00 to $75.00 per hour. I woould imagine they allow two hours for the work if that is what you need done,
FF