I have a '99 Grand Cherokee with about 219k miles on it. The last couple of weeks, I've noticed a slight "rattle" when i start it and it gets worse as I drive, accelerate. As it goes through the gears, the rattle changes in intensity but is always there. Any idea what it could be?

 

Welcome to CF. You didn't state which engine you have. The early 4.7 L V8's have an issue with the rocker arms becoming worn to the point where they fall off the valve, causing loud noises and a noticeable miss from the dead cylinder. Prior to that point there is a noticeable ticking from the rocker cover. It can be verified by removing the rocker covers, or use of a mechanics stethoscope to isolate the noise.

 

Your question and description is very generic, at 219K miles it could be almost anything.
Could you be a bit more specific about where it sounds like the rattle is coming from? (engine bay, rear, under your feet, outside, inside, etc.)
Might want to just do a walk around the vehicle and maybe poke your head under it while it idles if the rattle is always present. You may very well answer your own question with some very basic investigation.

 

Thanks guys......
Sorry about that.....it's the V6 engine. The noise I hear seems to be coming from the engine, I can hear it outside and inside the cabin.

 

They never made a v6 in that year.

 

Yeah, pop the hood and there's no V anywhere... Lol

 

Sorry, it's the 4.0L inline 6 engine.

 

most likely probably a bit of lifter or rocker noise. The I6 is a bit noisy but a great engine.