I took my 07 Aveo Sedan to a local mechanic and he supposedly checked everything. He changed out my bearings, valve gasket cover, spark plugs and wires, vacuum hoses, and tightened the bolts on my flywheel. I am still having a loud knocking sound that appears to be coming from my lower, driver's side by my engine. It does not appear to go away while I am driving, goes off immediately when I turn the engine off, and is it's loudest at idle. Other than the noise the car drives like a dream. I can not ask the mechanic because he had personal issues right before I picked up the car. Please give me some ideas. Thanks