Q: Makes a loud clunk noise when I try to start it

Hi there. Sounds like the engine may have water in the cylinder, fuel in the cylinder, or the timing chain may have broken. Try turning the engine over by hand with a breaker bar. If the engine will not move, then remove the closest valve cover to you and try rotating the engine at it can move. See if the rocker arms move. If the rocker arms do not move at all, then the timing chain has broken. If the rocker arms move, then I recommend removing all of the spark plugs and then try to crank the engine over by hand. If the engine is able to turn all the way over without hesitating or stopping, then there is water or fuel in the cylinders. This could lead up to either water getting in the cylinders from the air filter sucking in water or the head gasket may be split. If fuel is in the cylinder, then the fuel injectors could be leaking causing the cylinder to lock up. I recommend seeking out a professional, such as one from Your Mechanic, to help you diagnose your engine and determine what is causing it to not rotate all the way over.