Q: I DROVE THRU A FLOOD & MY CAR STALLED. NOW THAT IT STARTS ITS KNOCKING... WHAT CAN BE CAUSING THIS?

If you drove through deep water, chances are your engine took in some water and did internal damage to it. When engine suck in water, they cannot compress the water that gets into the cylinder, so it usually locks up the motor or causes a connecting rod to bend or break. It also could have damaged the engine bearings, which will also make a loud knocking noise. I would have the problem professionally diagnosed, and I would have it done soon. If the engine was in fact damaged, you will need to have it replaced or rebuilt, and it can be very expensive. You can contact a qualified professional, such as one from YourMechanic, diagnose the noise at your home or office. In the future, never drive through deep puddles or standing water. If you have no choice, then slow down to about 5 mph and coast very slowly through it, do not step on the accelerator any more than you have to, as that would allow more water to be sucked in.