Crank shaft oil seal - can it be changed with the engine in place?

I’ve noticed a small drip of oil coming from behind the plastic cover over the alternator on my Le Mans which I presume is from the crank shaft oil seal - though have not yet checked fully. Is it possible to change this seal with the engine in place or is it necessary to remove the engine and crank? ie a BIG job?

First make sure that’s where it’s coming from, also look at the high pressure hoses and banjos on the top front of the crankcase.

Front one is easy as it’s in the timing chest, rear one is a bit more involved.
But as Mike said check the rocker feeds first,
Good luck :+1:

Thanks Mike and Phil. At the weekend I will take the cover off and have a look.

What they said, but I think this post is in the wrong section.

Now moved