Q: Loud knocking noise.

When you say a knocking noise I assume you are referring to the engine. If the engine is indeed making the sound the first thing I would recommend is to check your oil level. This can be done by pulling the oil dipstick (usually indicated by a yellow top) and looking at the amount of oil on the stick. If unsure which dipstick is designated for engine oil this information can be found in your owners manual. If the engine oil is low I would recommend adding oil until the level is correct as soon as possible to prevent further engine damage. After adding oil, if the noise goes away the engine should be ok. If the noise does not go away permanent engine damage has occurred. This doesn’t mean the engine will not still perform its intended purpose but the noise may never go away. If the noise is a big concern of yours then replacement of some valve train parts may be necessary. Have your engine noise inspected by a professional.