I have a 2005 grand caravan 3.3l. when driving it seems to have a
slight rattle in the engine, once we hit around 43mph it turns to a
slight whistle or similar to a high pitched frequency sound. the faster

we drive the more profound it gets. It only does this while giving it
gas.
I brought it back to the dealer (still under warranty) they say it is
just normal drivetrain noise. I find this hard to believe. we love
the van but this sound is too annoying.