Carbon and aluminum are a match made in heaven. I have, to date, not had much luck separating them, to my satisfaction. Carbon and steel are much easier.
As a matter of fact, this is on my near term to do list. I'm planning to go through the EGR/intake system next month. I have a 10L ultrasonic cleaner on order. I'm told that water and the right frequency will separate them. Obviously this doesn't apply to electrical/electronic parts.
I don't know why I never closed the loop on this. I've mentioned it elsewhere, but my best experience to date has been using CarbonOff to clean intake components. It was designed for use in the restaurant industry, to remove baked on carbon from griddles. I have yet to see it damage aluminum in any way.
I bought a quart a couple of years ago and stil have half of it left. A little goes a very long way.
