Arosa howls with cold engine

Hello! I just registered here, because I have a problem with my Seat Arosa (built in 98)! So it is that with my Arosa (only when the engine is cold and it is cold outside) from 60 km/h there is sometimes a funny howling out of the engine room. It is not always at 60 km/h. Sometimes only at 80 km/h or so… so quite different. Sometimes the noise is only short there, then again a little longer… But as soon as the engine is warmer than 60 degrees, it does not come to m When the noise comes and I go down from the gas and then drive so 5-10 km/h slower, then it is gone and starts 5-10 km/h later again (e.g. I drive 60 and the noise comes… I go down from the gas… at 50-55 the noise is gone and I go back up to the gas…. at 65 it starts again). Sometimes even later… It also doesn’t matter whether I drive in 4th or 5th gear…. My car is standing outside, but sometimes also in the garage… no matter where it stands, the noise comes! I was already in the workshop, but they are not sure either. So far this was done: – V-belts changed – tensioning roller changed – oil change Next, the timing belt is on the alternating list and the 2nd tensioning roller! That’s what I’ve done so far, if the noise is: – down from the gas (noise does not go away directly, but only after 5-10 km/h – down from the gas and directly onto the brake (noise does not go away directly, but only after 5-10 km/h) – ventilation is switched off — > Noise remains – left without ventilation –> Noise comes anyway – radio off –> Noise stays – left without radio off –> Noise comes anyway Now I want to ask if you have already experienced something like this or if you can give me tips on what I could point out to my workshop! lg sonnschein88