aluminum left in water, in the heat?

[stabworthy]

I have a grimey miata cylinder head and intake manifold to clean before a port and "polish" later. I have stripped everything off to the bare block and valve guides. We are leaving on a 12 day roadtrip in a few weeks - would it bad to soak in a container in fresh water in the Texas sun to soften the grime to ease progress when I return? Also is there something mild enough to add to aid in the process? I imagine I wouldn't want a head stewing in dawn or simple green in 100° heat. Am I wrong?

[Strato_54]

I work with aluminum on a regular since i work in a fab shop, and when you weld aluminum it burns and turns black around the welds. we use lots of rubbing alcohol to polish after welding and grinding but to also prep when welding. since theres a global pandemic and all rubbing alcohol is either sold out or extremely over priced we like to use acetone. it works fairly nice after welding and eats at all the dirt pretty quick. just make sure that its a bare piece with no paint or markings that arent engraved. theres probably some scientific thing about using both on aluminum but its just what we have found works the best and have yet to see any side affects. another product we use is actually from the dollar store. its an "as seen on tv" labeled product called "La's totally awesome cleaner" and works really nice on aluminum and anything that needs a degrease. another would be vinegar, but ive heard that it can eat at damage aluminum if left for long periods of time with out rinsing.

[Slartibartfast]

Are you removing oily schmoo or just dirt? I doubt straight water would do much, and, yeah, I'd expect most cleaners to be corrosive if left long enough. Solvents should be fine, though, and might work pretty well depending on what you're trying to shift.

[stabworthy]

I mostly want to soften the oily carbon deposit in the runners and maybe float some loose oil remaining in oil passages. after I return home I'm going to properly pressure wash, degrease, and process them down to clean bare aluminum blocks. 

I was wondering would it doing more harm than good? I think i heard once that aluminum can't be left in a dawn water solution for long periods of time.