One of our farm trucks is making some noise from the valve cover. It is a 2000 F150 7700 XL with the 5.4L. The noise is coming from the passenger side valve cover only, and it isn't the ticking of the camshaft and valves. I can only describe it as a constant buzzing sound. My first thoughts are something with the timing chain, but if anyone else has any ideas let me know. Thanks!

 

Its called the PCV valve. Mine also does this I think it may be time to replace it. When I do the old test of putting my finger on the bottom of it, it still seems to operate though.

 

Good call on the PCV valve, the mechanic said the same thing. Got a new one ordered, hopefully that does the trick