I have a 92' Dakota with a 3.9 magnum with 256k miles on it. For the last few days it has been making a rattling noise, kinda like a heat shield is loose or something, but none are. I know it's not a lifter, piston, or connecting rod because it doesn't increase in speed when I revv the engine up. Any suggestions would be greatly appreciated, thanks.

 

Well if it doesnt increase with engine rpms then its probably something rattling. Hold your pcv line closed to see if the valve is rattling around. Check the exhaust manifold heat shields if you have them. Check the converter to see if it came loose inside.

 

pin point exactly where the noise is coming from. if its coming from the front then most likely its your timing chain. if its from the exhaust then i would say cat.. my 96 has a loose timing chain at the present moment. ive got one just havent had the time to put it in yet. they also can come with a tensioner now. which would probably be your best bet.