plain old soapy water probably won't cut it (ha ha). There are water-based formulations designed for degreasing parts- things like Simple Green, Mean Grean, Something-or-other Purple.

If you have some really tough grease, then try Mother's Mag Cleaner- available in auto stores. That comes with a warning- it WILL etch aluminum if you don't thoroughly rinse it off. It will discolor paint as well.

Also, lighter mineral spirits will work better for cutting grease than diesel. That also comes with a potential problem- the vapor pressure will be lower as will the flash point. Basically- you'll be breathing more of the solvent and it's easier to light it on fire.
Even with diesel I would advise working in a well ventilated area (like outside).

The ultimate (well, relatively) will be something like Berryman's Chemtool, carburetor cleaner. Very good at degreasing. Kind of expensive (but you can buy a gallon with a dipping accessory), very flammable.