I will disagree with truckernix. The only proper way to do this task is to remove the timing cover. The seal installation requires that it be driven in. Doing this 'in situ' is asking for trouble.
When you remove the timing cover to install a new seal, you will flatten the flange and install a new timing cover gasket too. Unless you have other issues, this will solve your leak.
I have braced myself for the onslaught of folks who have done this in place and have nary a problem.
Stuart
