My 1999 F150 4.2 5 Speed keeps giving this ticking noise coming from the drivers side of the engine. Its not the manifolds because I just put headers on it. But it gets louder and louder everytime I start it up. I was told maybe that it is a lifter stuck or something but I'm not too sure. The engine has 410,000 on it as well as the transmission. I would really like to get it fixed.

 

Yank the valve cover and see what you can find.

 

It could be the headers, I'd retorque the bolts at the heads and collectors.