[77Birdman]

If pulling the motor is not an option (would be the best way to do the job), and power washing proves too messy.... I would try an engine degreaser that comes in a spray bomb. You can get that stuff at Auto Zone. Spray it on, then lightly hose off with water. You may be able to use your small steam cleaner to touch up areas. When you get ready to paint a trick I learned long ago was to use aluminum foil to 'mask' up areas that do not get painted. Works like a charm on hard to tape things.