Gunk Engine Cleaner, light brush stubborn spots, rinse well.
Don't let it sit on there more than about 5 minutes, might fade colors.

 

Hook your garden hose up to a hot water outlet inside your house, a soft brush, and some cleaner and have at it.

 

thanks for all the input. Simple green didn't work very well. Dawn dishsoap is next, and we'll go from there. I can't get pictures to load.

 

go to home depot or lowes an get wire an electrical cleaner doesn't make black engines turn grey or white. a lg can is about $8 good luck bud

 

We use orange cleaner on our engines. We spray them down good before we wash. A few times a year we hit them with S-100 to keep the black looking good.

 

I bought some aluminum wheel cleaner at Auto Zone the other day to clean the wheels of my car........man it cleaned every bit of brake dust/grim, road grim and salt spray. Might try getting some of that and shooting it in a test area.

 

HD sells their brand of engine cleaner in a spray can. I got a free sample can but have not had a chance to use it so can't speak to how well it works, but it might be worth a try. My experience with their cleaning products has been pretty good for the most part.

 

I use bleach white for stubborn spots. Put it on a rag, do not spray it on. Wipe it good with a soft cloth. Clean with a wet cloth. If it does not come off then I doubt if you will get it off.