I have a 99 1500 5.9l, that I just picked up. It has a hissing sound between 1500 and 3000 RPMs once I step on it, it goes away. It idles fine and doesn't backfire (those are the things I've seen common on web searches). Any thoughts as to what it could be or what I need to do, if anything. This is my first ever dodge, so I'm not familiar with what is common place with these trucks.

 

What kind of aircleaner do you have ?

 

Welcome to DF.

If you have the stock air cleaner assembly, it may just need tightening down and/or a new air cleaner gasket. A few dollars at O'Reillys (or equivalent) and there ya go. In theory, at least.

If you have an aftermarket air cleaner assembly, such as a CAI kit or a round unit, this hiss may be normal.

 

or an exhaust leak in the manifold

 

exhaust leak would get louder, mine has a blown manifold gasket on the driverside and it just makes driving against a concret center devider on the freeway painful as hell with the window rolled down lol

 

I have a hissing sound and traced it to my water pump/fan clutch assembly. So open the hood, rev it up and see if you can pinpoint.

 

mine has a slight hiss from my 14x3

 

thats what im thinking it is, the hissing '" sucking sound '" annoys alot of people.