Flash rust on critical engine surfaces

Hi everyone. I searched but could find an answer, so hopefully this isn’t a repost. I’m building an engine, and various aspects of life have led to new/freshly machine parts sitting for a year. I have some flash rust on some critical surfaces (most concerning is crank journals). It seems very mild.

Wondering if you all have thoughts about when to try to fix by hand vs take it back to the machine shop.

Yes, you could clean it up yourself. Can be done with as simple as some strips of wet and dry sandpaper cut to the width of the journals, spray with WD40 and wrap around journal. Then use a shoe string to rotate back and forth, cleaning and working to finer grades. Finishing with metal polish on strips of microfibre cloth. Videos online showing how.

Negatives are time consuming, possibility of affecting flatness of bearing journals, smoothness of surface finish and final dimensional tolerance.

I have done by hand with great success, getting the pressure right to get sandpaper to rotate is the tricky part.

For the future, engine fogging oil can help prevent this reoccurring.

Thanks for the tips Cam, and the advice for next time Mike. The guys who bored/deck my block warned me about this, but at the time I figured I'd have the motor together in a month or so...lesson learned.

By the way, 1000 grit sandpaper followed by blue magic polish worked great seems to have gotten the job done. Point taken on being careful about even wear...I can see how it helps to have an experienced hand here. Not sure there's any good way to tell past high points that will be picked up by a micrometer.

Joseph,

I totally learned this lesson the same way you are. :)