89 245dl, b230f engine, 131k

so i'm out in the car park last night and giving the car a quick look-over after doing some other maintenance (emission problems recently), strangest idea hit me to crank it up, lift the dipstick up, and lo, there's air blowing out of the tube, felt on my face like an aquarium air pump, just little pulsations, really, not wind, it smells really foul like partly burnt fuel.

thought to myself well, it's just because it's cold, lots of blow-by, so i went out on my little drive, when i got there, i repeated this, engine warm now, but same results.

i know my pcv system is clear, i've had the car for about 15k miles, doesn't seem to foul the oil or anything (i change it myself), maybe it's just as the #4 piston rises and falls it blows then sucks, i wouldn't have felt the suck from several inches back. i'll be doing a compression test really soon! but until then, i'm curious if this is normal. somebody run out and try this! it's the strangest thing to me! it seems like the pcv would maintain a slight negative pressure in the engine.

thanks,

michael