i did a resent compression test and it was like this 200 90 180 180 i had a oil leak and it was found that the rear camshaft seal was blew out and i repaced it and fixed the leak we started the car and found that the smoke had stoped coming from the exhaust but now we have a loud knock coming from in the engine what do u think might be the knock and what should i buy to fix it. and what should i start looking at first