It is not exactly a major problem, but the engine will not run right and you do run the risk of valve train damage. It will most definitely cause a ticking sound and may be louder when the engine is cold (cold oil is thicker).

 

is it possible that having a stuck lifter gets unstuck? my blazer (2002) used to maki that ticking sound and a squeaking sound too. i took the belt off and put it back on the trouble shoot the squeaking and the tapping sound went away. is this possible. let me know what you think

 

If both noises went away when you removed the belt, the lifters where not the cause of your tapping noise.