under hood aluminum corrosion/remediation

[DrewPT]

I`m in the throes of cleaning/correcting the engine compartment of my `87 560SEC while the engine is just ready to go back in after a rebuild. For the steel, I`ve ground down any rust, used Eastwood AfterBlast (aqueous-based phosphoric acid solution) on any areas I`m still not sure about (like with pits), cleaned/dryed with Pre (an acetone-based solvent), and then coated with urethane-based Miracle Pant. I`d like to do the same for the white, scaly aluminum corrosion on some sections under the hood before the new insulation material goes on.

While both the AfterBlast and Miracle Paint are advertised as used for aluminum as well as steel, from what I`ve read it sounds like aluminum is generally trickier to work with. Some think phosphoric acid is not as good as Alodine, but I will be spot repairing and am in no position to detach the hood and fully strip it per the Alodine treatments. I want to leave the good sections of paint, and not have other chemicals leech under the edges where the corrosion will be ground down. Has anyone here had experiences with spot-correcting corroded aluminum/painted areas?

Relatedly, one of the heat shields needs reinforcement (this is a replacement part but it`s a thin, weak section) and I`d like to use fiberglass cloth and silver Miracle Paint, so it`s less noticeable. Since this aluminum has been exposed (just cleaned with Dawn degreaser then the Pre acetone-based spray) for years, would the naturally oxidized (I`m assuming but it just looks like normal aluminum) top finish readily accept the paint/fiberglass, or would sanding need to be done (in which case I imagine exposes a fresh layer, so then some chemical treatment may be necessary)?

Thanks,
Drew

[jimmie jam]

The product that I`ve used for years is L.C. WAX "Alumaslick". I just did the complete underside/suspension on my 911. I typically clean with WD40 first before applying a thin coat to the aluminum. It is clear and does not leave any residue. Keeps everything looking new. It is anti corrosion, removes oxidation and does not contain silicone. FWIW.

[Accumulator]

DrewPT- Hey, I simply *LOVED* my W126 SECs! WONDERFUL cars...sure glad you`re treating yours to an engine rebuild instead of writing it off! Heh heh...any issues with the seatbelt extenders? Anyhow...Sorry to butt in without any answers to your Qs, they`re just outside of my wheelhouse

Noting that you gotta be careful about weakening anything structural, I`d be surprised if your AfterBlast (never used that one, I use Rust Bullet`s Metal Blast) weren`t fine for your spot-repairs. I myself would try that on the heat shield prior to what you have planned for refinishing it. I`d use some kind of "paint over [corrosion]" product prior to your topcoat (I`d use RustSeal even though we`re talking aluminum).

jimmie jam- Hey, there`s another product I`m not familiar with! Thanks for mentioning it, sounds nice and clean (of great importance to me).

[William_Wallace]

The product that I`ve used for years is L.C. WAX "Alumaslick". I just did the complete underside/suspension on my 911. I typically clean with WD40 first before applying a thin coat to the aluminum. It is clear and does not leave any residue. Keeps everything looking new. It is anti corrosion, removes oxidation and does not contain silicone. FWIW.

I’ll have to check this out. I live in northeast I’m mostly trying to protect steel with my vehicle I use either cosmline or fluid film I do have some aluminum around my pool area.. thanks for the Info