My free Centurion from craigslist has chosen to give me heartburn again.

I repacked the bottom bracket a few months ago with fresh grade 25 bearings and grease. I even reused the stock bottom bracket plastic sleeve, after cleaning, to keep gunk from the tubes out of the bearings. A few days ago I noticed some noise from the bb area and after getting off the bike, back pedaled the crank and found a lot of clunking and grinding.

Put the bike in the stand and pulled the cranks, and adjustable cup. The cup, bearings and spindle came out with a lot of rust flakes the size of dimes as well as rusty grit mixed in with the grease. My previously new but stock spindle is pitted now. I checked the down and seat tubes for rust or gunk as I did when I first tore down the bike a rebuilt it: clean. Then I stuck a finger down the left chainstay and came out with a ton of rust flakes and rusty grit. The right chainstay seems fine.

Are the rust flakes actually spalling off the inside of the chainstay? I cleaned it out with WD-40 and a bore brush as best I could. I did ride the bike in the rain a few times this winter when my fendered commuter was out of commission. One storm had me riding with my feet and hubs under water. There are those small breather holes in the chainstay near the dropouts for gasses to escape during brazing (I believe). Has anyone experienced this? I will most liely strip the frame and do some sort of rust prevention treatment.

Thanks for reading,
Jered