You are probably right, I did not tighten it, I guess that is what I thought I was doing! What causes the squeal? It seems to come and go at idle, but I cannot hear it under power. Thanks again, ScoobySince your model year TJ has a spring loaded automatic belt tensioner, it shouldn't need adjusting to make it tighter. As asked by 4Jeepn, what's the issue where you felt the belt needs to be tighter? By pushing HARD on the belt between its widest unsupported span with your thumb, it should deflect about a half-inch.