tonight was the first time i noticed this noise. I shut the truck off, got out, stood outside my door getting stuff out of the truck and I heard this noise, sounds like when you make an electric spark, or when your at a desk or something and you lean forward on it more and more, like the stress noise. It would do it for bout 1 full second, stop, then 2-3 seconds later do it again, wasn't extremely loud, but you could hear it within 10 feet of the truck. It was coming from underneath the truck, couldn't exactly spot it, most like in the front half of the truck. I wonder if this could be related to the rattling sound I've been hearing since August 05.

 

Sounds like it could possibly be the exhaust cooling off. Also if the A/C was on it the water could be running down and landing on the exhaust maybe.

 

just a thought but the rattle could be your catalytic converter going bad.any loss in performance?

 

About that, I bought my truck in August of 05 and I've been hearing a rattle ever since, I figured it was the cat going bad/already was bad, dealership wouldn't do anything. So I had a shop take a look and they said it was the cat, so I ordered a magnaflow and had that put on. Now, I can only hear the rattle when I go into OD (~40mph) with the windows up, and since it was warm for awhile, I didn't close em til couple weeks ago. Then I started hearing the same noise. I don't know if this cat is defected and somethings also wrong with it or not. Performance wise my truck feels like im a towing a house with 285's and 3.55 gears with the weight of the quad cab and 4x4, so I couldn't tell ya.

 

It's the exhaust...when you heat metal it expands...when you cool it, it contracts. What you hear is the metal settling back in. Most vehicles do it.

It's especially bad if you only drive short distances, and the whole system doesn't get a chance to warm up.

And it's not necessarily the converter. My 99 Grand Prix does it, and it doesn't even have a converter [8D]

 

mine does it too.. like Rom said its normal for it.. sounds like a tink tink tink tonk tonk kinda noise.. yea.. normal.. almost all cars do it..and especially with a thinner walled exhaust tubing the sound is more apperent.. like on cheep import crap where they use 1/32" walled exhaust tube..stuff is think and contracts and exapands quickly.. hope this helps!!