It’s an aluminum block and there are some high spots of white powdery corrosion.

I was able to gently scrape most off using a (dull) metal paint scraper and a green scour pad, but there are some stubborn spots remaining.

Also I vacuumed out any fine particles from the scour pad that landed in the ports, but if I missed any that “may” have gotten deeper inside is that cause for worry?

2 Answers 2


The best or accepted way was to run the manifold face on emery cloth which was on a flat plate or surface plate.

This would gradually reduce the high points.

If the amount needed was significant then a machine shop could machine it.

  • It’s not the manifold itself but the engine side that needs cleaning
    – ohmmy
    Commented Feb 22, 2021 at 11:42
  • Same applies - but if the head has studs then they need to come out.
    – Solar Mike
    Commented Feb 22, 2021 at 11:56

Slice through the garbage on the aluminum face and all the way around each stud using a NEW razor. Do not use a rotary ANYTHING. If the edge gets nicked grab another blade. Scratches here and there on the aluminum will not be a problem. And for goddsake leave the studs alone. Nothing good will happen there. Lastly get some solvent and a rag.

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