Hi guys ..my 110 200tdi .has started howling when the revs are peaking for a gear change upwards ..normally happens in 3/4 gears .drop the revs back a touch and it goes immediately it's quite deafening .turbo is kicking in nicely and you can just here it working at times under the other howl ...what have I missed .!!!! Cheers from a head scratcher.

id look for a split in a turbo hose

Will do cheers .