aluminum engine parts

[rtbrick]

I cleaned the engine compartment on a `98 Camry today and it came out fairly good except for the aluminum valve cover and intake manifold. It looks ok, but the metal is sorta stained in many places (like it just got darker). I tried using a steel bristle brush (toothbrush sized) and some APC. Helped some. Does anyone have any tricks-of-the-trade for this problem?

[EBPcivicsi]

I would try some metal polish on it.

[NozeBleedSpeed]

Definitely try a polish like Mothers aluminum and mag polish.

[rtbrick]

The aluminum is rough, not smooth. Seems like the polish would get caught up in the rough surface. I`ll give it a shot though.

[Poorboy]

unfortunately you`ve done all that can be done...:(

[CharlesW]

Maybe some of the wheel cleaners that are spray on, rinse off would help. Someone might try some on an old manifold or wheel to see just what would happen. It seems that some of them are not acid based and might not be too corrosive.