text: acid to dissolve aluminum before cast  iron?seized al deposit on engine crkshft journal-acidtoremove-tidybowl? aluminum alloy? connecting rod seized on engine (lawn mower) crkshaft, left seized/melted al material on crankshaft (cast iron) journal. i've heard "tidy bowl" toilet cleaner will remove deposits??? i tried another cleaner that has hcl acid - test sample attack both al & cast iron - appears too strong (if diluted, will still react w/iron). i need to preserve the polished cast iron journal surface and just remove/dissolve the aluminum deposits. need educated answer to remove aluminum deposits before attacking cast iron. any common cleaners? tomato paste? ketchup? any and all help! appreciated. thanks in advance (1st post :)). easiest way may be to (very carefully!) melt the aluminum off with a torch.  i think cast iron has a melting point of about 900c, and aluminum has a lower melting point of around 700c, so maybe you can melt the aluminum and let gravity remove it for you. the only problem might be iron tends to retain heat rather better than aluminum so it would be a slow process...  good luck!