omega 2,5dti 117000km `01 aut. have the following proplem: with cold motor whistles something after approx. 3km.(comish noise) but also only if I take the gas away-by giving gas it goes away. the fun lasts until the engine is warm. no noise comes from the ventilation! opel dealer is stunned and changes to VERDACHT 2 tension belts.can anyone help me further?