Uhm, what model Diatom filter is it? Or rather, about how much water would you figure the glass jar holds, a gallon or smaller than that?
I use 2-3 true measured cups of DE powder with my XL model filter, it has a gallon jar -- for reference think of those big ol' "institutional size" jars of pickles. The most common cause of noise for me would have to be bubbles in the impeller. The impeller spins in such a way it actually drives CO2 and other gasses out of solution and then will blow them into the tank.
It's also pretty normal that the motor sort of smells, gets hot, and is noisy. It is likely it needs to be oiled, as many folks forget that. If you have some sewing machine oil, or 3in1 oil, put a few drops in the "oil port" ...good luck finding it though.