Should I replace toilet fill valve or cap
Should I replace the cap or the complete fill valve?


Just the cap.

The most important part of the fill valve is the cap assembly and the valve it contains. The seal between the cap and the valve body may be compromised, and the seal is in the cap. There appears to be nothing wrong with the valve body or float assembly.

If you don't know how, you just shut off the water and, while holding the valve body with one hand to prevent bending and spinning, turn the cap assembly counter (anti)-clockwise and lift it off (pop the float rod loose from the float arm first).