Engine block discoloration/staining?

[fourarmo]

What are these brown stains on the block? Below the black super charger cover. Does anyone else have these ?

 

[Jinba ittai]

Oxidation/rust. I sprayed mine with this stuff as soon as I got it home per recommendations on this forum. Seems to be working.

 

[fourarmo]

So what do you do if its already discoloured?

 

[Jinba ittai]

I’d probably go at it with a wire brush and then spray the ACF-50. I don’t know though. Someone else may have a better suggestion.

 

[crestima]

What are these brown stains on the block? Below the black super charger cover. Does anyone else have these ? View attachment 70153

@Jim

What are these brown stains on the block? Below the black super charger cover. Does anyone else have these ? View attachment 70153

That's caused by the combination of heat and oxidation which is common and forms over time. @Jinba ittai's suggestion to use ACF-50 is a good one as it helps to clean and to protect the alloy going forward, but I'd avoid using a wire/steel brush since it may be too abrasive and scratch the metal surface. Instead, I used these brushes pictured below, purchased from Amazon, which proved pretty effective, albeit may require a little more effort.