Engine block cleaning question in Nissan L6 Forum Posted September 28 Hey guys, I'm doing some top end work on my L28. New cam, headers, and ITBs. I pulled off the cylinder head and have that mostly clean of the old gasket. My question is on the block itself, what is the best way to clean it without getting debris into the coolant and oil passages? Should I just stuff bits of rag in them and vacuum the debris off before pulling the rags? I searched around and kept finding conflicting advice. Thanks for the help.