1. Knock sensors usually stay in place until you get codes. Replacements are expensive and a pain to get installed correctly.

2. There is metal behind the hole in the block.

3. No need for additional oil. If you want to add any oil for the rings, about 1 tablespoon per cylinder.

4. Gizmo?

5. Always take pics during disassembly, it helps a lot. Yours is not as complicated as a turbo.

6. Either engine degreaser, carb cleaner, brake cleaner. Just don't use too much so that it pours into the combustion chamber. Use Seafoam as a separate procedure after it is all back together and working again.

Klaus
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Always willing to listen, just not able to take direction.