I'm helping a friend replace his timing belt on his 2.0 Zetec engine. We put in the camshaft peg and the camshaft holding tool and set up the valve timing and the belt tension etc.. When we take everything out and turn the crankshaft, we notice that the exhaust side cam procket turns and so does the camshaft, but after about a quater turn the camshaft sprocket continues to turn but the camshaft doesn't. If we keep turning eventualy the camshaft will start to turn again. We then notice that the valve timing is all off again. Is this normal or is something broken between the camshaft and the cam sprocket.
Thanks, Brian