Thanks for the reply I'm new to the forum and tried to post a picture but couldn't figure it out

Just changed all the timing belt and water pump components and the belt is scrubbing on the inside of the tensioner idler. Looking at the old gates tensioner idler it was doing the same but I never heard it.

What could be causing this and how can i fix it?

Just replaced my timing belt and water pump on my 1996 10v 850. Replaced idler, tensioner pulley and hydraulic tensioner. All genuine volvo parts used. Torqued everything to spec. Started it up and the belt wanders back and forth close to the edge with a rubbing/ screeching sound. Please advise how ...