I recently washed my engine. I went to the nearest car wash, I waited till the engine was cool, I covered my pod with a plastic shopping bag, lightly went over the engine bay with the car wash engine/tyre cleaner (my engine bay was already fairly clean, if a bit dirty may be advisable to use some engine degreaser) with care to avoid wetting the fuse box and other electrics, Then hose off using the high pressure clean, but don't pull the trigger, just use the low pressure until all the soap/degreaser is removed. Then dry off most surfaces with a crappy chamous, presto all clean :D