i seem to be losing my power-steering in my mk3 cavalier 1.7td anytime i try to move from idle lik wen im moving out of a parking space or if ive to do a 3 point turn. i also noticed it happens if i hit a puddle when im turning or turn when going over a ramp.

ive checked it for fluid and it was okay, theres no whine so im guessing the pump is fine but i wud say that the power steering belt could do with being replaced ?? but ive heard its combined with the timing belt is that true? the timing belt does seem to be pretty loose so could this have an effect ???
thanks!