Got the heads pulled off a motor I'm working on. Everything looked good until I found a little spot of surface rust in one cylinder about the size of a q-tip head. Was just at the top of the piston ring travel. Sprayed some wd40 on a rag and rubbed it off. Should I be worried about it?? Motor spins freely, and didn't see any score marks in the cylinder. I'll take a flashlight to it in the morning tho for a better look. I do not wanna do a full motor build for this truck, but I also don't want any issues a year or 2 down the road after doing all this work.

 

If it's above the ring, why would it matter, if it's below the ring it'll probably scrape it clean most rikki-tik the first time you crank the engine. If you're worried about it, little 600 grit wet or dry, lubed with WD40 would probably buff it off. Unless it's pitted, can you catch a fingernail on it? If it's that bad, hone or bore + hone, but when you say it's one spot, very small, and surface rust, and it rubbed off, its probably nothing to worry about.

Disclaimer: Kansas hayseed speaking, never had a minutes training in an engine building shop, so

 

Thanks Drew. That's kinda the way I'm looking at it. Just looking for opinions to back up my thoughts on it. Been doing bolt on stuff for years, but haven't actually torn a motor down and put it back together since high school. It was in the ring travel, not above it. That's why I'm just slightly concerned. But yea, still feels smooth.

 

What Drew said - not a problem.

 

Spent a few minutes looking closer at it today.

 

Use scotchbrite and WD-40.

 

NEVER use scotchbrite. It has aluminum oxide in it. Just the dust from that stuff is a big engine killer. It's highly abrasive and will get into your bearings.

 

What about a fine emery? Like what you'd use on a crank?

 

I assumed he would take the proper precautions. But good point.

 

I guess I can get the piston about halfway down and use masking tape to cover the bore. Just FYI, if this was a small block Chevy I was working on then no, I wouldn't be concerned at all cause they're so cheap to rebuild. Only reason I even care is cause it's(and to the moderators please don't close this thread because of this) is it's a duramax going into a truck I'm not even sure I'm gonna keep. Not gonna go crazy with it, but planning on more power than stock