Is definitely very bad to use a pressure washer because water gets into alternator and other electric items.
Go watch a You Tube video on how to do this. It probably says use a grease cleaner, a scrub brush, sponge and hot water and be careful to stay away from the alternator.
www.youtube.com/watch?v=_k_S-Bv1v14 ....... Clean engine without water using ArmorAll tire foam and a leaf blower.