aluminum head discoloraton

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Starting to clean up the engine on the 81 everyone has been helping me with. It appears to be raw aluminum, unpainted, which I gather is correct. But it has some darkening and a reddish staining in places. Zap doesn’t seem to touch it. A wire brush and hard scrubbing will budge bits of it. Any suggestions as to what this is and how to get rid of it?

Jack Davis

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Addendum to the last. I neglected to specify the head is what I am talking about.

Jack

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I should also add that the stainless bolts are just there to test the threads. I had 17 bolts that broke off and had to be drilled out, and they all came out fine tapped at 1/4 x 28. Two holes had been drilled out to 3/8 during an earlier restoration and I’ll be using Heli coil or equivalent to get them back to 1/4″ I will also be grinding off the markings on the bolt heads. Got almost a quart of rust, some of it chips 3/4″ square, out of the cooling chamber. It isn’t pretty now, but virtually rust free.

Jack

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You can try CLR [Calcium, Lime &Rust Remover] it’s very good at removing corrosion from nickel, brass, copper etc. Use a wire brush, gloves, eye and face protection. Then power-wash thoroughly. It usually will brighten up the aluminum

I’ve also used toilet bowl cleaner, like ‘The Works’ or Lysol. Same safety concerns.

Greg Long

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