crack in cyl. wall, need advice/opinions

[rickjordan]

Just a quick back story. This issue is with my '92 190E (170,000 miles) For the longest time the car has a had a rough/loping idle. Give it a little gas and it smooths out. Had a compression test done and #3 is low compared to the other cyl.

Now to present day, I bought a video borescope and just looked inside #3 cyl and it looked like there was a crack. Amazingly I can still see the factory bore marks, but I also saw what appears to be at best described as a hash mark/crack. It is brownish in color, which is easy to see against the gray cyl. walls.

If I had the ability to connect my borescope to the computer, I would upload a pic. I will see if I can take a pic of the video screen and see how that comes out.

Now, obviously a crack anywhere will cause low compression numbers. My question is, is it possible to have a crack in a cyl. wall, but not have any issues with coolant being burned out the exhaust? I don't have any coolant in the oil, or oil in the coolant.

Thanks