Get the astonish engine degreaser. cost 190 per bottle and is a quite concentrated. You can get it from Al-Fateh in centaurus. If you cant find it there, I have half a bottle with me, i can give you that.
wash the engine with a stream of water, spray the degreaser once, leave it for 4-5 minutes so it can do its job. use a brush to agitate the grease if you think its caked on. wash. If still not happy, repeat the process.