Hi, I bought an engine out of a wreck about a year ago knowing that it had some work done to it. I put it in my car and it was running well but doing some funny things. *the oil catch can would slowly fill with water. *It was using a little bit of water but had no visible leak. *little bit of oil in cooling system. *if I ran the engine with the radiator cap off after it got hot I would get a few bubbles every now and again. *I did not have milky oil I decided that I must have a cracked head or blown gasket so I took the head off and took it into the engine reconditioner to get it checked out. The head was fine and the reconditioner explained that I have a square section ..... something or rather?? which is similar to O-ringing the block except the groove around the top of each cylinder is deeper and has its own copper ring sitting in it. He advised that I need to get a new block (which I don't want to do) or buy some expensive crap to fill the grooves in the block and then use a MLS head gasket. The head gasket that was in it looks like it has had the rings cut out to fit snug around these copper rings and I'm thinking that I might buy a genuine Nissan one and try and do the same thing? or maybe a copper gasket and try to get the holes cut slightly bigger to fit around these rings. Any help would be appreciated I haven't measured them yet to see how thick they are or how much they protrude out of the head but it is not a lot. I have included some pictures. https://plus.google.com/115990995745...tos?banner=pwa (https://plus.google.com/115990995745524995502/photos?banner=pwa)