Is it knocking at idle? How about when you give it a little gas? Is it a dull thudding sound? If so and you can hear it from the oil pan it's likely a rod bearing. A quick way to check & see if it's any of the accessories is to just remove the belts and start it up & see if it still does it.86_cutlass said:so replacing my water pump did nothing for me and my motor still knocks but i borrow a stethoscope and figured out its a low end knock so i am just going to save up for a new engine. but i found a rust-free trunk lid and passenger door for $150 even though i need both doors one is good