I had the head gasket replaced in January. Had numerous oil leaks prior to this repair. After that repair I noticed that there were intermittent dinging noises after I shut the engine off. I still notice this noise. Lately the engine sounds a little loud when I first start the car in the morning. Also, when I had an oil change last week, they said there was some oil leaking and the pan might need to be replaced. Advice on what to investigate, please? Thank you.