I have a 2000 3.9l Dodge Dakota and one day when I started it it sounded not good and almost like a diesel sound to it. All the power was there so I checked plugs, fluids, ect and everything seems alright but once it warms up a few miles down the road it sounds normal untill it sits and gets cold again? I have not done anything prior to it so I couldn't blame it on anything. Any ideas? It's not showing any codes either.

 

Check out the exhaust manifold gasket and bolts. Very common on the 4.7, don't know if it is common on the 3.9, though.

 

i have the same problem on my 2.5. i second paynes opinion

 

I think I have a similar issue. possibly more than one. Mine sounds like piston slap, but I think there might be an exhaust leak too. Is there a gasket material I can use instead of taking the manifold off? With 200k on it, Im worried about snapping bolts....

 

gasket maker... but bolts are better than rubber if they snap on their own