Q: Knocking from the engine

Although it is unlikely to be the cause, I would recommend checking your engine oil level. If your oil level is low, the engine will not be lubricated sufficiently enough to function properly and will therefore make knocking sounds as the metal engine parts come in contact with one another. If the oil level is at the specified level, I would recommend having an engine inspection performed by an engine diagnostics professional. It is possible that your engine may have suffered internal damage and may require replacement of valves, camshafts, lifters, and/or other internal engine parts. Only a thorough engine inspection will reveal the true causes of this issue.