Q: Would a faulty front main bearing seal drop oil pressure to the hydraulic lifters?

Hi there. Lifters will tap if there is no pressure to them causing a gap or if the lifters are out of adjustment. Put on a mechanical oil pressure gauge to the engine and check for oil pressure. If there is sufficient oil pressure, then the lifters are sticking and either need to be cleaned or replaced. If there is no oil to the lifters, then there could be an oil gallery plugged. If the engine oil has not been changed for a while, I suggest changing the oil first before doing anything else. An oil change can clean up a lot of gum in the engine making it work properly. If you need further assistance with your vehicle, then seek out a professional, such as one from Your Mechanic, to help you with the lifter tap after the timing belt was replaced.